How to Build Bigger Arms: What an Arm Specialization Phase Actually Requires

Most people treat arm training like an accessory. They train chest, back, or shoulders, then finish the workout with a few curls and pressdowns and assume that, because the arms were trained, they should continue to grow. That can work for a while, particularly when someone is new to lifting. Eventually, though, a muscle that you genuinely want to improve has to become more than something you get to when the important work is finished.

An arm specialization phase changes the way the program is organized around the goal. That doesn’t mean doing an absurd number of curls or adding an extra arm day onto an already crowded week. It means deciding that arm growth is temporarily a priority, then making room for that priority through exercise order, volume allocation, exercise selection, progression, and recovery.

If your arms have looked essentially the same for the last year, the answer may be more training. But before adding more, it’s worth asking whether the training you’re already doing is organized well enough to produce the result you want.

1. Reallocate Volume Before Adding Volume

The easiest response to a lagging muscle is to add more sets. If ten sets haven’t worked, do twelve. If twelve haven’t worked, do fifteen. Eventually the program becomes a collection of everything you were already doing plus an increasing amount of work for the body part you’re trying to bring up.

That ignores the recovery cost of the rest of the program.

Your arms are already involved in much of your upper-body training. The triceps contribute to pressing, while the elbow flexors contribute to most pulling movements. Adding substantial direct arm volume without accounting for that existing work can increase fatigue faster than it improves the stimulus.

A specialization phase should therefore begin by moving training resources, not simply creating more of them. If arms become a higher priority, chest, back, shoulder, or total upper-body volume may temporarily come down. You’re creating room for the arms to receive more high-quality work while preserving your ability to recover from it.

Specialization always involves a tradeoff. You cannot make everything the highest priority at the same time.

2. Put the Priority Muscle First

Exercise order is one of the simplest ways to change the emphasis of a program without changing a single exercise.

Whatever you train first is performed when you’re least fatigued. Your ability to produce force is higher, technique is generally easier to maintain, and the target muscle hasn’t already accumulated fatigue from several other movements. If the arms are always trained after an hour of heavy pressing and pulling, you’re asking them to grow from whatever training quality remains.

That may be fine when arm development is secondary. It makes less sense when it becomes the goal.

During an arm specialization phase, direct arm work can move to the beginning of a session or receive its own dedicated training day. You may even place the muscle you most want to improve first within the arm workout itself. Someone with particularly underdeveloped triceps doesn’t necessarily need to alternate which muscle goes first simply for the sake of fairness. Priorities should determine exercise order.

Your program should reveal what you claim matters.

3. Train the Elbow Flexors, Not Just the Biceps

When people say they’re training biceps, they often use “biceps” as shorthand for everything on the front of the upper arm. Anatomically, elbow flexion involves more than the biceps brachii.

The brachialis contributes strongly to elbow flexion, while the brachioradialis also becomes an important contributor depending on forearm position. Changing your grip changes the contribution of these muscles. A supinated curl places the biceps brachii in a favorable position to contribute. Neutral-grip hammer curls and pronated reverse-curl variations alter that relationship and provide a different challenge to the elbow flexors.

This is why an arm program built entirely around slightly different versions of the same supinated dumbbell curl leaves something on the table.

Exercise variety becomes useful when the exercises are actually different. A supinated curl, hammer curl, and reverse curl represent different forearm positions and slightly different demands on the elbow-flexor group. That gives you a more complete reason for including several exercises than simply choosing three curls because they use different pieces of equipment.

4. Choose Exercises by Where They Load the Range

Two exercises can train the same muscle and still provide meaningfully different stimuli.

What matters is not only which muscle is moving the joint, but where in the range of motion the exercise becomes most difficult. The external resistance created by gravity, a cable, a machine, or another form of loading changes relative to the joints as you move. As a result, one curl may challenge the elbow flexors heavily when they’re relatively lengthened, while another creates more difficulty toward the shortened end of the movement.

That distinction gives exercise selection a purpose.

Instead of asking whether preacher curls are “better” than spider curls or cables are “better” than dumbbells, ask what each exercise contributes to the program. If all three movements become hardest in essentially the same portion of the range, the variety may be more cosmetic than physiological.

A better arm program exposes the muscle to meaningful loading across different portions of its available range. You’re building a collection of complementary exercises rather than collecting exercises for their own sake.

5. Give the Triceps Different Shoulder Positions

The same principle becomes particularly useful when training the triceps because one of the three heads—the long head—crosses both the elbow and shoulder.

That means shoulder position changes the length and mechanical environment of part of the triceps. A pressdown, lying extension, overhead extension, and dip are therefore not interchangeable simply because they all involve elbow extension.

Pressdowns are useful, but an entire triceps program built around the arm staying beside the torso limits the positions through which you train the muscle. Overhead extensions place the shoulder in flexion and lengthen the long head differently. Lying extensions create another loading profile. Dips or pressing variations expose the triceps to still another combination of shoulder and elbow mechanics.

You don’t need every possible angle in every workout. Over the course of a specialization phase, however, using different shoulder positions gives you a more complete triceps stimulus than repeatedly changing attachments on the same pressdown.

6. Pair Biceps and Triceps Strategically

Training biceps and triceps together allows you to use antagonist pairings: perform a biceps exercise, rest briefly, perform a triceps exercise, then return to the biceps after the appropriate recovery period.

This makes arm training unusually well suited to efficient programming. While one muscle group is working, its antagonist is not performing the same task, allowing you to accumulate a considerable amount of direct arm work without turning the workout into a long sequence of isolated straight sets.

The important distinction is between training density and rushing.

Alternating biceps and triceps shouldn’t mean moving so quickly that performance collapses. If the purpose of the set is hypertrophy, you still need enough recovery to produce high-quality repetitions and maintain the intended loading. The pairing simply allows some of that recovery time to be occupied by training the opposing muscle.

Done well, you can fit more productive arm training into the same amount of time without turning every set into conditioning.

7. Specialization Can Justify More Exercise Variety

Most muscles don’t require an enormous exercise menu in a normal training program. If a body part is receiving only a moderate amount of weekly volume, two well-chosen exercises may provide everything you need.

Specialization changes the problem.

Once you deliberately increase direct work for a muscle, relying on one or two movements for all of that volume can become limiting. Repeating the same joint angles, loading profiles, grips, and positions across a large number of sets may make the additional volume increasingly redundant.

That’s where three or four complementary exercises can make sense.

The word complementary is doing most of the work. Four exercises should give you more than four names in your training log. You might combine different forearm positions for the elbow flexors, different shoulder positions for the triceps, and exercises that emphasize different portions of the resistance curve.

Variety has value when it expands the stimulus. Novelty for its own sake simply makes progression harder to track.

8. Use Intensifiers for a Reason

Drop sets, tri-sets, and mechanical-advantage sets can all make an arm workout considerably harder. That alone doesn’t make them better.

Their value is that they allow you to extend productive work under circumstances where a conventional straight set has reached its limit.

A mechanical-advantage set is a good example. You begin with a variation in which your leverage is relatively poor, take that movement close to or to its prescribed endpoint, then shift into a mechanically stronger version that allows you to continue working the same general musculature. The load doesn’t necessarily have to change because your position changes your ability to continue producing force.

That is different from randomly adding intensity techniques because you want the workout to hurt more.

Intensifiers should have a job. They can increase training density, extend a set, increase the amount of work performed with a given load, or expose the muscle to a different fatigue environment. Used selectively, they can be very useful during specialization. Used everywhere, they mostly make fatigue harder to manage.

9. Progress Arms in Smaller Increments

Progressive overload becomes awkward with smaller exercises because the equipment often increases in increments that are disproportionately large.

Going from a 30-pound dumbbell to a 35-pound dumbbell is a 16.7% increase in load. Nobody would expect someone squatting 300 pounds to casually add 50 pounds the next week simply because that happens to be the next weight available.

Yet that is effectively what we sometimes ask people to do with curls.

Microplates, adjustable dumbbells, cable stacks with smaller increments, and fractional loading can make progression much more realistic. When smaller load increases aren’t available, progression can also occur through repetitions, improved range of motion, more consistent execution, or eventually additional sets.

The important part is that the progression is measurable.

If you curled 30 pounds for ten technically consistent repetitions and several weeks later you can perform twelve with the same execution, something improved. If you immediately jump to 35 pounds and turn the movement into a combination of lumbar extension, shoulder flexion, and hope, the number on the dumbbell increased while the training stimulus became harder to evaluate.

10. Change the Prescription After You’ve Adapted to It

Consistency is necessary for progression because you need enough repeated exposure to an exercise and training method to become proficient and determine whether it’s working. Changing exercises every workout prevents you from establishing that baseline.

But consistency doesn’t mean keeping the same program indefinitely.

Eventually, progress slows. Repetitions stop increasing. Loads stop moving. An exercise that once produced a very strong local stimulus may begin producing more joint discomfort or systemic fatigue than useful progression. A training method that worked well for several weeks may simply have given you most of what it currently has to offer.

That is when variation becomes useful.

You might change the rep range, loading method, resistance profile, exercise, or way movements are paired. The change should answer something you observed in the previous phase. If the program is still working, there’s very little reason to abandon it. If progress has clearly flattened despite adequate recovery and execution, changing part of the prescription gives you a new problem to adapt to.

The goal is neither endless novelty nor stubborn consistency. It is to keep a useful stimulus progressing.

Build the Program Around the Priority

Bigger arms don’t require secret exercises. They require the same thing every other stubborn training goal eventually requires: better organization.

If arm development is genuinely important to you, give it a period in which the rest of your training reflects that decision. Move volume away from lower-priority work. Train the arms before they’re exhausted. Understand the muscles you’re trying to develop. Choose exercises because they contribute different loading conditions. Progress them with increments that make sense. Use advanced methods when they solve an actual programming problem, and change the prescription when you have evidence that the current one has stopped moving forward.

An arm specialization phase should look different from simply adding an arm workout.

Otherwise, you haven’t specialized. You’ve just added more training.

Your Lower Back May Be Limiting More Than You Think

The lower back tends to enter the conversation only when it hurts. Until then, most people treat it as something that should stay out of the way while the “real” muscles do the work. You train your legs with squats, your hamstrings with Romanian deadlifts, your back with rows, and your shoulders with presses. The lower back is simply assumed to be along for the ride.

But that’s not really how those movements work.

Your lower back is one of the structures responsible for maintaining the position that allows force to move through the rest of the body. In a squat, your legs and hips may be producing most of the force needed to move the weight, but that force still has to pass through a trunk capable of holding its position. In an RDL, your hamstrings and glutes may be strong enough to keep working, but if your spinal erectors can no longer maintain the position of your torso, the set is effectively finished. The same thing can happen in a bent-over row, a loaded carry, a deadlift, or even a standing press.

This is where the lower back becomes more than a support structure. It becomes part of the system that determines how much of your strength you can actually use.

A person can have strong legs and still struggle to express that strength in a squat because the torso loses position under load. The hamstrings can have more to give during an RDL while the lower back is already exhausted. The upper back can still be capable of producing force in a row, but that capacity becomes irrelevant once you can no longer hold the position required to perform the exercise well. In each case, the muscle you’re trying to train may not be the thing ending the set.

That distinction is important because it changes how you think about weak links. A weak link isn’t necessarily the muscle producing the least force. Sometimes it’s the structure that can no longer maintain the conditions that allow everyone else to keep producing force.

Working Hard Doesn’t Mean It’s Fully Trained

This is also where the usual response of “I already squat and deadlift, so my lower back gets plenty of work” becomes a little too simple.

Of course it gets work. The spinal erectors are involved heavily in those exercises. But involvement and complete development aren’t the same thing.

A muscle can accumulate a lot of fatigue while performing a supporting role without necessarily being trained in the way that would best improve its strength or endurance. During a squat, for example, the lower back may be working very hard to resist the tendency of the torso to collapse forward. That can make it tired. It doesn’t automatically mean the squat is the best exercise for improving every quality of lower-back strength.

This is one of the reasons direct training can make sense even for someone who already performs plenty of compound lifts. It allows you to isolate the problem more deliberately. You can choose the position you want to strengthen, control the amount of load and fatigue, and build capacity without relying on the lower back to improve as a side effect of something else.

That doesn’t mean everyone needs to start hammering heavy good mornings three times a week. The lower back already participates in a lot of training, so direct work has to account for everything else you’re asking it to do. If you’re squatting, deadlifting, doing unsupported rows, and performing heavy hinges during the same week, piling more heavy hinge work on top may create more fatigue than progress. The point of direct training is to address a limitation, not to create another one.

Different Exercises Challenge the Lower Back Differently

It also helps to stop thinking of every posterior-chain exercise as interchangeable. An RDL, good morning, 45-degree back extension, horizontal back extension, and reverse hyper can all involve the lower back, but the mechanical demands aren’t identical.

One useful way to organize them is by looking at where in the movement they tend to become most demanding.

Romanian deadlifts and good mornings place a large demand on the lower portion of the hinge. As the torso travels farther away from upright, the weight gains more leverage against you. The muscles responsible for extending the hips and maintaining the position of the spine have to produce more force to resist that leverage. This makes RDLs, standing good mornings, and seated good mornings useful when you want to become stronger while the torso is farther forward.

A 45-degree back extension changes that profile. It generally moves the challenge more toward the middle and upper portion of the movement, although this is where it becomes important not to pretend these categories are exact. Bench angle, range of motion, body proportions, technique, and where you hold the weight can all change the exercise considerably. Holding a plate against your chest creates a different resistance profile than holding it at arm’s length. Increasing the range changes the problem again. The 45-degree extension is better thought of as a flexible tool that can be manipulated than as an exercise that belongs permanently to one exact point on a strength curve.

Horizontal back extensions and reverse hypers shift the problem again. As the torso approaches horizontal during a back extension, or as the legs rise toward horizontal during a reverse hyper, the external demand increases. These movements can therefore be useful for strengthening the upper portion of the range.

The reverse hyper also deserves to be considered separately from a conventional back extension because the body is organized differently. In a back extension, the lower body is relatively fixed while the torso moves. In a reverse hyper, the torso is supported while the legs move. Both involve the posterior chain, but they ask the system to solve the movement in different ways.

None of this means the lower back is neatly divided into three separate sections that can be isolated with the correct exercise. That would be taking the strength-curve idea too literally. These classifications are useful because they help us think about where an exercise tends to create the greatest external demand, but the exact profile will always depend on how the exercise is performed.

What This Means for Your Training

You don’t need every lower-back exercise in the same program. In most cases, that would simply be redundant.

A better approach is to look at what your current training already provides and where you appear to lose capacity. If you already perform heavy squats and RDLs, you’re getting a considerable amount of work while the torso is inclined forward. Adding another heavy good morning may give you more of the same thing when what you actually need is additional work with a different resistance profile. A 45-degree back extension or reverse hyper might make more sense.

If your position consistently breaks down near the bottom of an RDL or good morning, strengthening that deeper hinge position may deserve more attention. If you’re strong there but lose control or force as you approach extension, another exercise may be more useful. The exercise should solve a problem you actually have.

The same principle applies to strength and endurance. The lower back needs enough strength to tolerate heavy loads, but it also needs enough endurance to maintain position as a set continues and fatigue builds. A person can be reasonably strong for a few heavy repetitions and still have the lower back become the limiting factor during longer sets. On the other end, someone can perform endless light back extensions and still lack the strength required to hold position when the loading becomes meaningful.

Good programming develops both qualities while accounting for the work the lower back is already doing elsewhere.

That’s really the larger point. The lower back shouldn’t be treated as a fragile area that you hope survives your training, nor should it be buried under endless extra work simply because “a strong back is important.” It’s trainable musculature with a specific role in the system. When it can maintain position under greater loads and for longer periods of time, the muscles above and below it have a more stable structure through which to express their strength.

Sometimes the reason a lift stops improving isn’t that the obvious muscle needs to become stronger. Sometimes the rest of the system is already capable of more, and the structure connecting it all together simply hasn’t caught up.

Can an Algorithm Really Tell You How Much Weight to Lift?

There is an understandable appeal to removing the guesswork from training. If an app knows what you lifted last week, how many reps you completed, and what the program asks you to do next, it seems reasonable that it should be able to tell you exactly what weight to put on the bar. That is especially attractive when progressive overload is commonly explained as some version of doing more over time.

One common way to turn that idea into a program is to increase the training weight by a fixed percentage from week to week. The 2.5% figure is not a law of human performance. It is simply a practical example of a small, manageable progression: if you lifted 100 lbs this week, the program might prescribe 102.5 lbs next week, then approximately 105 lbs after that, continuing upward as long as the increases remain achievable. The number is small enough to seem realistic, while still creating a clear progression rule.

There is nothing inherently wrong with using a progression rule like that. For some people, particularly newer lifters, it may work quite well for a while. The problem begins when a simple progression rule is presented as though it is an individualized prediction of what someone should be capable of lifting. Increasing everyone's training weight by 2.5% because another week has passed isn't really an individualized model. It is a predetermined progression applied to individuals.

The difficulty is that strength doesn't progress at a uniform rate, either between people or within the same person over time. Someone who has been lifting for three months can improve incredibly quickly, while someone who has trained seriously for ten years may spend months trying to add a few pounds to the same exercise. Even that distinction is incomplete because training age doesn't tell us how experienced someone is with a particular movement. An experienced lifter who has never performed a front squat may improve rapidly for several weeks simply because they are learning how to perform the exercise better.

That improvement is still real in the sense that they can now lift more weight, but it doesn't necessarily mean that their muscles became 15% stronger over that period. Early improvements can come from better intermuscular and intramuscular coordination, improved technique, greater comfort under load, better understanding of effort, and a growing willingness to actually push the set. A beginner may add 10 or 20% to an exercise over a relatively short period without experiencing anything close to a corresponding increase in muscle mass.

This immediately creates a problem for any algorithm that assumes everyone's performance should move according to the same percentage.

It becomes even more complicated when we consider how differently people approach training. Two people can have the same training age, perform the same exercise, and possess roughly similar strength, yet require very different loading decisions. One person may consistently underestimate what they are capable of and stop sets with 4 or 5 reps left in the tank. Another may routinely push every set to the edge of failure regardless of what was prescribed. Someone else may be technically excellent and unusually consistent from session to session, while another person's execution changes enough that the same number on the bar doesn't always represent the same exercise.

A coach learns these things about an athlete over time. You learn that someone's reported 2 reps in reserve is usually closer to 4. You learn that another athlete will attempt almost anything you put in front of them, so the coaching problem is occasionally holding them back rather than convincing them to work harder. You learn who responds well to larger jumps in weight, who needs smaller increases, whose performance varies considerably from day to day, and who is remarkably predictable.

None of this means that algorithms are useless. It means that predicting training load is a much more complicated problem than multiplying last week's weight by 1.025.

What Are We Actually Trying to Predict?

The first thing to clarify is the algorithm's prediction target.

A useful question is:

Given what this person has demonstrated recently on this exercise, what load gives them the best chance of completing today's prescribed reps at approximately the intended level of effort?

A person's 1RM can still provide useful context, but the practical training decision concerns the load most likely to produce the intended reps and effort in today's session.

If the workout calls for three sets of 8 reps with approximately 2 RIR, the algorithm is trying to predict the weight most likely to create that outcome.

That is a different problem from simply estimating maximal strength.

A person's recent training already provides useful information. If they performed 185 lbs for 8 reps with approximately 2 reps remaining, that set tells us something about their current capacity. If they later perform 190 for the same reps and effort, or perform more reps with 185, we have evidence that their usable strength on that exercise has improved.

This gives us a better foundation than predetermined weekly increases because the progression now follows demonstrated performance.

A simple estimate could begin with:

Estimated reps to failure = completed reps + reps in reserve

If someone performs 8 reps with 2 left, we can treat that set approximately like a ten-rep maximum for estimation purposes.

An established rep-max equation can then turn that performance into an estimated current strength value. The exact equation will never be perfect, but that is acceptable because the purpose is not to discover someone's true physiological maximum to the pound. We are trying to create a useful estimate that can be updated continually as more information becomes available.

The important change is that every training session becomes another observation.

The Athlete's History Should Become More Important Over Time

Initially, an algorithm knows almost nothing about someone. It has to rely on general assumptions about relationships between reps, load, effort, and strength. That is unavoidable.

But the longer someone uses the system, the less those generic assumptions should matter.

Imagine a general equation predicts that someone should be able to perform 8 reps with 2 RIR at roughly 80% of their estimated max. After several months, however, the athlete's training history consistently shows that they perform that prescription better around 75%.

At that point, continuing to insist that they should use 80% because a generalized equation says so would defeat the purpose of having individual data.

The model should gradually learn the athlete's own relationship between load, reps, and effort for each exercise.

This distinction also needs to exist between exercises. Someone's bench press, back squat, split squat, and dumbbell row do not necessarily follow the same rep-to-load relationship. The more data an athlete accumulates on an exercise, the more that exercise should develop its own prediction model.

Training history can therefore become increasingly specific:

This person, on this exercise, in this rep range, at approximately this effort, has historically performed best around this percentage of their estimated capacity.

That is much closer to meaningful individualization.

Training Age Plays a Role

Training age should probably influence the model. Not by assigning everyone with the same experience the same progression rate but in determining how stable we expect someone's performance to be.

A new lifter can change dramatically from week to week because they are learning how to lift. Their technique and coordination improves, their perception of effort changes, and they become more comfortable producing force. Their predicted load may therefore need to move rapidly.

An experienced athlete is usually different. If someone with ten years of serious training suddenly appears to have increased their strength by 15% in a week, that observation deserves more skepticism. It could be real, but it could also reflect an unusually good session, a different technique, inaccurate RIR reporting, changes in equipment, simple measurement noise, or anabolics.

So rather than using training age to determine the predicted weight itself, I would use it initially to influence the amount of expected variation around the prediction.

An athlete with less than a year of experience might reasonably have a much wider prediction range than an advanced athlete whose performance has been stable for years.

For example, if the model predicts a working weight of 200 lbs, the novice prediction might initially be something like:

200 lbs, with substantial expected variation

while the experienced athlete might receive:

200 lbs, with a much narrower expected range.

Those ranges should eventually stop being determined primarily by training age. Once enough individual data exist, the athlete's actual historical variability should take over.

Someone with eight years of training may still have highly variable performance. Someone with two years may be incredibly consistent. Their own history is better evidence than the category we initially placed them in.

Effort Creates Another Layer of Uncertainty

The model also has to account for the fact that reps in reserve are subjective.

If a workout calls for 8 reps with 2 remaining, the system may assume that someone reporting 2 RIR could have completed approximately 10 reps. But that assumption only works if their perception of effort is reasonably accurate.

Some people become quite good at estimating proximity to failure. Others are consistently wrong.

This is another area where a coach develops context that is difficult to capture from a single number. Over time, however, an algorithm could begin learning from the discrepancy between predicted and demonstrated capacity.

If someone routinely reports 2 RIR but occasionally performs a calibrated set close to failure and demonstrates that they actually had 5 reps available, the model now has evidence that this person's RIR reporting is systematically conservative.

It could begin adjusting future predictions accordingly.

Again, the system becomes more useful when it learns from behavior rather than assuming that every person's "2 RIR" means the same thing.

Then Life Happens

Even after accounting for training age, exercise history, effort, and previous performance, we still have the problem that human performance fluctuates.

Sleep, nutrition, carbohydrate availability, stress, soreness, recent training, illness, travel, and motivation can all influence performance, but none of these variables behaves like a simple switch.

Sleeping poorly doesn't mean that you will necessarily perform poorly the following day. Someone can sleep 4 hours and still hit a PR. Another athlete can sleep 9 hours, eat perfectly, report low stress, and have a terrible session because his mind is somewhere else.

That makes lifestyle information useful, but dangerous if it's interpreted too literally.

An algorithm that says:

"You slept poorly, therefore reduce today's load by 7%."

may be just as misleading as one that completely ignores sleep.

A better interpretation is that lifestyle variables change the uncertainty of today's prediction.

If someone's recent training suggests that 200 lbs is appropriate, poor sleep and unusually high stress might make us less confident that 200 will behave normally today. They don't necessarily tell us whether the correct weight is 190, 200, or 205.

The prediction could therefore remain centered around 200 while the expected range becomes wider.

This is probably one of the most important distinctions in the entire model.

Lifestyle data should generally influence confidence in the prediction before the athlete trains, while actual performance during the session should quickly become the stronger source of information.

If the athlete slept badly but their warm-ups are fast, their technique looks good, and their first working set is considerably easier than expected, the system should respond to what is happening in front of it.

A coach naturally does this.

They may walk into the session expecting the athlete to be flat because they know the athlete was up all night. But if the athlete starts moving extremely well, the coach changes the plan.

The sleep data provided context rather than becoming a command.

The First Working Set May Be the Best Readiness Test

This leads to what may ultimately be the most useful feature of the entire model.

Instead of expecting an algorithm to perfectly predict someone's capacity before they touch a weight, we can use the algorithm to choose the best starting load and then use the athlete's actual performance to update the session.

Suppose the model recommends:

200 lbs for 8 reps at 2 RIR.

The athlete performs the first set and reports:

200 × 8 @ 4 RIR.

We now have better information than we had 10 minutes earlier. Whatever the sleep score, stress score, calorie intake, or training-age model predicted, today's actual performance suggests that the initial recommendation was conservative.

If instead the athlete performs:

200 × 7 @ 0 RIR,

we also learned something. Today's capacity is probably lower than expected.

At that point, the actual set should outweigh most of the softer readiness information.

This creates a hierarchy that resembles how good coaching already works:

What is the athlete demonstrating right now?

Then:

What have they demonstrated recently?

Then:

What does their longer-term history tell us?

Then:

What contextual factors might affect today's performance?

And finally:

What do population-level assumptions suggest when individual information is unavailable?

The farther down that hierarchy we go, the less confidently the information should dictate the training decision.

What the Algorithm Could Actually Look Like

If we were going to build a more defensible training-load algorithm, I would structure it around a series of estimates rather than one progression percentage.

The first layer would estimate current exercise-specific capacity from recent working sets:

Load + Reps + Reps in reserve

Each set provides an estimated strength value.

Several recent observations are then combined, with more recent and more informative sets receiving greater weight. A hard set performed last week should probably tell us more about current capacity than an easy set performed three months ago.

That produces an estimate of current capacity for the specific exercise.

The program's target is then introduced:

Target reps + target RIR

If the workout asks for 8 reps with 2 remaining, the system estimates what percentage of the athlete's current capacity has historically produced approximately that outcome.

Initially, it may use generalized rep equations. As individual data accumulate, the person's own exercise-specific history should increasingly replace those general assumptions.

Training age can initially influence the expected variance around the prediction, with less experienced athletes receiving wider ranges because their performance is likely to change more quickly.

Exercise experience should modify that further. A ten-year lifter performing an unfamiliar exercise should be treated differently from a ten-year lifter performing a movement they have trained weekly for five years.

The individual's actual history of prediction errors should eventually replace much of this categorical information. If the model repeatedly predicts 200 lbs and the athlete reliably performs best at 190, the algorithm should learn that rather than repeatedly making the same mistake.

Lifestyle information can then widen or narrow the confidence range around the day's recommendation without automatically forcing the load upward or downward.

Finally, the first meaningful working set becomes the strongest available information and allows the system to adjust subsequent sets if necessary.

The result is less like:

Last week's weight + 2.5% = today's weight

and more like:

Based on your recent performance, exercise history, training experience, individual response to previous load increases, reported effort, and today's uncertainty, this is the most likely useful starting load. We will update that estimate based on what you actually do.

That is a fundamentally different way of thinking about the problem.

Where the Coach Still Has an Advantage

Even this more sophisticated model remains imperfect because it is attempting to turn a large number of interacting human variables into measurable inputs.

A coach does something similar, but not entirely through arithmetic.

They see how the athlete walks into the room. They see whether the warm-up looks normal. They notice if someone is protecting a knee without realizing it. They know that an athlete is usually conservative when choosing weight, or that another one becomes reckless when they feel good. They can tell when technique changed enough that last week's numbers are no longer directly comparable to today's. They can recognize when someone needs to be pushed and when the same person needs to be restrained.

More importantly, a coach can ask why, while an algorithm only sees that performance dropped 8%.

A coach might learn that the athlete broke up with their girlfriend, slept three hours, skipped breakfast, has an exam in two hours, and still wants to train hard because training is the only part of their day that currently feels normal.

None of those things automatically determines what weight should go on the bar, but together they change how the coach interprets what happens next.

That doesn't mean coaches are infallible. Coaches guess too. Good coaching isn't the absence of uncertainty. Much of coaching is making increasingly educated decisions from incomplete information and then adjusting as reality gives you better information.

An algorithm can do some of that as well, particularly when it has enough longitudinal data. However, the difference is that we should be careful about presenting mathematical precision as physiological certainty.

A recommendation of 187.5 lbs looks incredibly precise. The human being lifting it may not be.

A Better Approach?

There is value in using technology to remove unnecessary guesswork from training. Most people don't have an experienced coach watching every set, and an adaptive recommendation based on actual training history could be considerably more useful than asking someone to randomly choose a weight.

The system should make the best available prediction, communicate how uncertain that prediction is, and improve its recommendations as the athlete provides more information.

It should become less dependent on generic rules the longer someone uses it. Training age may help establish an initial expectation. Exercise history makes that expectation more specific. Previous performance begins shaping the athlete's individual model. Effort calibration tells us how much confidence to place in subjective feedback. Lifestyle factors modify our uncertainty about the day. Actual performance then tells us whether the prediction survived contact with reality.

That is a much harder problem than adding 2.5% every week. It's also much closer to what coaching actually is.

What the Algorithm Could Actually Look Like

All of this still leaves us needing to put a number on the bar. If I were trying to build the algorithm, I would use everything above to solve three separate problems: estimate the athlete's current capacity, calculate the load most likely to satisfy today's prescription, and then establish how much uncertainty should exist around that prediction.

The starting point would be recent exercise-specific performance. If we know the load, completed reps, and estimated reps in reserve, we can approximate how many total reps the athlete was capable of:

Estimated reps to failure = completed reps + RIR

A set of 185 lbs for 8 reps at approximately 2 RIR therefore behaves roughly like a 10RM. That performance can then be converted into an estimated current capacity using an established rep-max equation. Using the O'Connor equation as an example:

Estimated 1RM = Load × [1 + 0.025 × estimated reps to failure]

For 185 lbs and approximately 10 available reps:

185 × [1 + (0.025 × 10)] = approximately 231 lbs

I wouldn't use that one set as the answer. The model could combine the most recent several exposures, giving greater weight to more recent performances. As an initial structure, the last five useful exposures might receive weights of 40%, 25%, 15%, 12%, and 8%. That produces a rolling estimate of the athlete's current capacity on that specific exercise.

Suppose that estimate is 250 lbs and today's program calls for 8 reps at 2 RIR. We again treat the prescription as approximately 10 available reps and reverse the equation:

Predicted load = estimated current capacity ÷ [1 + 0.025 × target available reps]

In this case:

250 ÷ 1.25 = 200 lbs

So 200 lbs becomes the initial prediction.

The next step is where the model begins becoming genuinely individual. If the equation repeatedly predicts 200 lbs, but this athlete consistently achieves the intended reps and RIR closer to 190, the system should learn from that discrepancy. We could calculate an individual correction factor:

Individual correction = actual successful load ÷ predicted load

If 190 consistently works when 200 was predicted:

190 ÷ 200 = 0.95

Future comparable predictions would then be multiplied by approximately 0.95. This correction should be specific to the exercise and, where enough data exist, the rep range. The more the athlete trains, the less the model depends on generalized rep equations and the more it depends on that athlete's own history.

The final pre-workout calculation would therefore look roughly like:

Personalized predicted load = estimated load from current capacity × individual correction factor

That gives us the number we think the athlete should use. It doesn’t tell us how certain we should be.

Initially, training age and exercise familiarity can establish the expected range around that prediction. A reasonable starting assumption might look something like:

Less than 1 year training: ±10%

1-2 years: ±7.5%

2-4 years: ±5%

4+ years: ±3%

These numbers are starting assumptions rather than established physiological thresholds. An unfamiliar exercise would widen the range further because performance can change rapidly while the athlete learns the movement. Once enough individual data exist, however, the system should stop relying primarily on training age and instead calculate how far this particular person's actual loads normally deviate from its predictions.

Lifestyle information can then widen that range when today's performance is unusually difficult to predict. Poor sleep, unusually high stress, low calorie intake, soreness, travel, or illness would not automatically subtract weight from the recommendation; they would reduce our confidence that the athlete will perform exactly as expected.

The output might therefore look like:

Predicted starting load: 200 lbs

Expected range today: 190-210 lbs

Then the athlete actually lifts.

At that point, today's performance should begin replacing prediction with observation. If the prescription was 200 × 8 at 2 RIR and the athlete performs 200 × 8 at 4 RIR, the starting prediction was conservative. If they perform 200 × 8 at 0 RIR, it was aggressive. If they only complete 6 of the prescribed 8 reps, that objective failure should carry even more weight than the subjective RIR estimate.

A simple first version could adjust the next set approximately 2% for each RIR the prediction missed by, while missed reps could carry a larger adjustment, perhaps around 3% per rep. Those coefficients would need to be tested against real training data rather than treated as established truths.

The complete system therefore becomes fairly simple despite the number of variables behind it:

1. Use recent performance to estimate current exercise-specific capacity.

2. Use today's reps and RIR target to calculate the most likely starting load.

3. Correct that prediction using what the system has learned about the individual.

4. Attach a range reflecting how uncertain the prediction is.

5. Let today's actual performance update the recommendation once the athlete begins training.

The precise coefficients would almost certainly change as real data accumulated. That is partly the point. A genuinely individualized algorithm should become less dependent on the assumptions it was built with as it learns how the individual actually performs.

Understanding the Stretch-Shortening Cycle: Muscle, Tendon, Stiffness, and Explosive Movement

The stretch-shortening cycle is easy to recognize but much harder to explain clearly. We see it whenever an eccentric action immediately precedes a concentric one, such as dipping before a vertical jump, absorbing force before pushing off during a sprint, or rapidly loading the arm before a throw. The eccentric phase improves the performance of the concentric phase that follows, allowing greater force, impulse, velocity, or movement than would be possible from a concentric-only action. The difficulty comes from explaining why this happens, because the stretch-shortening cycle is not driven by one mechanism. The stretch reflex contributes, but so do pre-activation, residual force enhancement, tendon elastic energy storage, and the interaction between muscle and tendon. In fast athletic movements such as sprinting and jumping, the behavior of the muscle-tendon system becomes especially important.

To understand that interaction, it helps to separate the muscle fibers from the tendon even though they function as one connected system. Muscle fibers actively generate force, while the tendon transmits that force to the skeleton and can temporarily store and return mechanical energy. Because the muscle and tendon sit in series, a change in the total length of the muscle-tendon unit does not require the muscle fibers and tendon to change length by the same amount. Depending on the task, more of the movement can occur through the muscle fibers, more can occur through the tendon, or the contribution can be shared between the two. This is where much of the confusion around the stretch-shortening cycle begins, because joint movement is often assumed to reflect what the muscle fibers themselves are doing.

During high-speed movement, the tendon can undergo substantial length change while the muscle fibers remain relatively stable. In sprinting, for example, the plantar-flexor muscles are already active before the foot contacts the ground. Ground contact then creates an external force that drives the ankle toward dorsiflexion and lengthens the calf–Achilles muscle-tendon unit. At the same time, the calf musculature is contracting strongly and resisting that lengthening. The force created between the external loading of the limb and the active muscle causes the Achilles tendon to elongate while the muscle fibers themselves may change length relatively little. When the direction of movement reverses into push-off, the tendon recoils and contributes to rapid plantar flexion while the muscle remains active.

This is the context in which the term quasi-isometric becomes useful. The muscle fibers are not perfectly motionless, but their change in length can be small compared with the speed and range of movement occurring at the joint. That allows the muscle to continue producing substantial force without having to shorten at the same extreme velocity as the limb. The force-velocity relationship tells us that muscle fibers are capable of producing more force when they shorten slowly than when they shorten very quickly. Tendon deformation therefore provides a mechanical advantage: the body can move rapidly while the muscle fibers remain in a slower, more favorable force-producing condition. The tendon is not creating force independently. The muscle remains the active source of force, while the tendon changes how that force is transmitted and how the movement is distributed across the muscle-tendon system.

This is also where tendon stiffness becomes easy to misunderstand. Tendon stiffness describes how resistant a tendon is to elongation under load. A stiffer tendon changes length less for a given increase in force, while a more compliant tendon changes length more. That property can be useful in different ways depending on the movement. In slow, high-force actions such as heavy strength training, large amounts of tendon deformation are not especially useful because the task does not rely heavily on rapid stretch and recoil. A relatively stiff tendon can transmit force efficiently while allowing the muscle fibers to operate under favorable conditions during a slow, force-dominant movement. This helps explain why tendon stiffness can be beneficial in strength-oriented contexts.

Fast stretch-shortening actions create a different mechanical problem because tendon deformation itself becomes useful. When the tendon elongates during the eccentric phase, it can temporarily store elastic energy and return some of that energy as it recoils during the concentric phase. The same tendon movement also allows the muscle fibers to avoid having to perform all of the rapid length change themselves. Both effects can improve the performance of the movement. The tendon therefore needs to deform enough to participate meaningfully in the stretch-recoil process, which is why simply trying to maximize tendon stiffness can become counterproductive when the goal is high-velocity stretch-shortening performance.

The elastic-energy equation helps explain why this becomes more complicated than saying that a stiffer tendon is automatically a better spring. Elastic energy is often represented as E = ½kx², where k represents stiffness and x represents displacement. If two tendons were stretched the same distance, the stiffer tendon could store more energy. The problem is that greater stiffness also makes the tendon harder to stretch that distance in the first place. Because displacement is squared in the equation, the amount the tendon actually moves becomes extremely important. A tendon with a high stiffness value that barely deforms during the brief loading phase of a sprint or jump may not provide the same functional benefit as a tendon that undergoes greater useful displacement under the forces produced by the athlete.

This is why the relationship between eccentric muscle strength and tendon stiffness is more useful than thinking about stiffness by itself. The muscle has to produce enough eccentric force during the loading phase to deform the tendon. Two athletes could have tendons with similar mechanical stiffness but behave very differently if one athlete can generate substantially more eccentric force. The stronger athlete may be able to stretch the tendon farther during the same brief loading period, allowing more energy storage and a greater contribution from tendon recoil. In that situation, the tendon behaves more compliantly during the movement even though its underlying structural stiffness has not necessarily decreased.

This distinction also explains an apparent contradiction in plyometric training. Tendon stiffness can increase during successful plyometric training while stretch-shortening performance improves at the same time. The reason is that eccentric muscle strength may increase faster than tendon stiffness. The tendon becomes slightly stiffer, but the muscle becomes even more capable of deforming it. The athlete therefore produces a more useful stretch-recoil interaction even though the tendon itself has not become structurally softer. The meaningful change occurs in the relationship between the force-producing capacity of the muscle and the resistance of the tendon to deformation.

The misunderstanding in training often comes from reducing the entire system to one tissue property. Tendons are commonly described as springs, which leads to the assumption that a stiffer spring must create a more explosive athlete. That idea overlooks the fact that a spring only stores meaningful energy if it can actually be loaded and deformed. It also ignores the role of the muscle in creating the force that loads the tendon and the role of the tendon in allowing the muscle fibers to remain relatively slow while the joint moves rapidly. As a result, training methods that increase tendon stiffness can be mistakenly treated as direct stretch-shortening-cycle training even when they are primarily improving a different quality.

Isometric training is a good example. Heavy or long-duration isometrics can increase tendon stiffness and may be useful for improving force production or other strength-related adaptations. Brief maximal isometrics can also improve motor-unit recruitment. Those adaptations may still be valuable for an athlete, but they should not automatically be treated as equivalent to improving the high-velocity stretch-shortening cycle. If the goal is to improve the rapid eccentric-to-concentric interaction that occurs during sprinting, jumping, or throwing, the athlete still needs exposure to fast stretch-shortening actions in which the muscle and tendon are forced to coordinate under those conditions.

Plyometric training is useful because it exposes the athlete directly to that interaction. The muscle must produce eccentric force rapidly, the tendon must accept and store part of the resulting load, and the entire system must transition immediately into a high-velocity concentric action. The value of plyometrics therefore goes beyond making a tendon stiffer or more compliant. They train the relationship between eccentric force production, tendon deformation, elastic energy storage and return, muscle-fiber behavior, coordination, and subsequent movement velocity. That is why low-volume, high-quality plyometric work can be highly effective even when the total number of repetitions is small.

It is also useful to separate the stretch-shortening-cycle adaptation from the speed benefit that can occur during the concentric phase of a plyometric. If the specific goal is to improve eccentric muscle strength relative to tendon stiffness, the concentric phase is not what creates that adaptation. The concentric phase can still provide an additional benefit because the preceding stretch-shortening action can allow the athlete to reach a higher movement velocity than they would from a concentric-only start. That higher velocity may then provide a separate speed-related stimulus. In practice, the same exercise can therefore train more than one quality, but those benefits should not be treated as though they come from the same physiological mechanism.

This also helps explain why plyometric volume does not need to be especially high. The desired adaptation is not dependent on accumulating fatigue or completing a large number of contacts. A small number of maximal-quality repetitions can provide the required exposure, while continuing to add repetitions after movement quality begins to fall may increase tissue loading without adding the same quality of stimulus. The goal is therefore to preserve the speed, eccentric force, and coordination of the movement rather than chase volume for its own sake.

The tendon’s contribution to movement also becomes easier to understand once energy storage is separated from energy generation. The tendon is not an active motor. It does not create energy on its own. Energy enters the system through muscular force and external loading, and some of that energy can temporarily be stored as elastic strain within the tendon. When the tendon recoils, that stored energy is returned quickly and contributes to the movement. The muscle is still producing force throughout the process, but the tendon allows some of the mechanical work to be stored and released in a way that would be difficult for muscle fibers to reproduce through rapid shortening alone.

A useful mental model is to think of the muscle as an active motor connected to an elastic spring, with the spring connected to a lever. In a slow strength movement, the motor performs most of the active work and the spring behaves primarily as a force-transmitting structure. During a fast stretch-shortening action, an external force rapidly loads the lever while the motor is already active. The active motor resists the imposed movement, which loads the spring. The spring stretches, the direction of movement reverses, and the spring recoils while the motor continues producing force. Because the spring changes length rapidly, the motor does not have to shorten at the same velocity as the lever. This allows the system to combine high external movement speed with relatively favorable force production from the muscle fibers.

The change in stretch-shortening-cycle performance can also be monitored without sophisticated equipment. One practical option is to compare a concentric-only jump, such as a squat jump, with a jump that includes a rapid eccentric loading phase, such as a drop jump performed for maximum height. The difference between those performances provides a rough indication of the additional contribution being gained from the stretch-shortening cycle. Both jump heights may improve at the same time, but if the drop jump improves faster than the squat jump, the stretch-shortening-cycle contribution has increased. If the relationship stops improving and begins to plateau, that may indicate that the current emphasis has already produced most of the available change.

The practical goal of stretch-shortening-cycle training is therefore to improve the ability of the entire muscle-tendon system to accept rapid eccentric loading and convert it efficiently into subsequent concentric performance. That requires enough eccentric muscle force to load the tendon effectively, tendon properties that allow useful deformation and recoil, favorable muscle-fiber behavior, and coordination that preserves the rapid transition between loading and propulsion. Heavy strength work, isometrics, eccentric training, and plyometrics can all contribute useful adaptations, but they contribute in different ways and should be programmed according to the specific adaptation they are intended to develop.

That does not necessarily mean stretch-shortening-cycle performance should be maximized throughout the entire training year. Greater tendon movement may support high-velocity performance, but a tendon that repeatedly undergoes larger excursions is also being exposed to greater mechanical loading. This creates a programming trade-off between maximizing performance and managing tissue stress. During periods farther from competition, greater emphasis on strength and carefully dosed isometric work can allow the athlete to develop force-producing and recruitment adaptations without continually maximizing tendon deformation. Plyometric emphasis can then increase when high-velocity stretch-shortening performance becomes more important. The basic exercises do not necessarily need to change completely between off-season and in-season training; the amount, frequency, and emphasis can change according to the demands placed on the athlete.

The most useful way to think about tendon stiffness is therefore in relation to the task rather than as an isolated quality to maximize. In slow, high-force actions, relatively greater stiffness can support efficient force transmission. In fast stretch-shortening actions, tendon deformation becomes valuable because it allows elastic energy storage and helps the muscle fibers operate at slower shortening velocities while the body moves rapidly. High-velocity stretch-shortening performance therefore depends less on whether a tendon can simply be described as “stiff” or “compliant” and more on whether the muscle can generate enough eccentric force relative to that stiffness to deform the tendon effectively. Plyometric training can improve this relationship by increasing eccentric muscle strength faster than tendon stiffness, allowing greater useful tendon deformation, elastic energy storage and return, and slower muscle-fiber shortening while the joint itself moves rapidly. The training objective is to develop a muscle-tendon system whose force-producing capacity and tendon behavior are appropriately matched to the velocity demands of the movement, rather than attempting to maximize either stiffness or compliance in isolation.

When Leanness Becomes a Stand-In for Health

The fitness industry has spent decades teaching people to treat leanness as one of the clearest visible signs of health. There is some validity to that association. Excess body fat can increase the risk of metabolic disease, impair physical function, and contribute to poorer health outcomes. But somewhere along the way, a useful observation became a cultural rule: if carrying too much body fat can be harmful, then being leaner must always mean being healthier.

That conclusion does not hold up very well.

Health is not a competition to see how little body fat a person can carry. Human physiology does not reward us indefinitely for becoming leaner and leaner, and there is no biological imperative to maintain the degree of leanness that much of the fitness industry now presents as an ideal. Body fat serves real purposes. It stores energy, contributes to endocrine function, protects us during periods of scarcity, and forms part of the energetic buffer that allows the body to continue functioning when conditions become less predictable. At some point, losing additional fat stops producing meaningful health benefits and becomes primarily an aesthetic pursuit. If pushed far enough, the same process that initially improved health can begin to undermine it.

The confusion becomes easier to understand when we separate health from the way health is represented.

Most of the things that make someone genuinely healthy are difficult to see. You cannot look at a photograph and know someone's blood pressure, insulin sensitivity, cardiovascular fitness, bone density, sleep quality, reproductive function, relationship with food, ability to recover from training, or likelihood of remaining capable and independent later in life. What you can see is body fat. You can see abdominal definition, muscularity, vascularity, and the sharpness of someone's physique. Because those qualities are visible, measurable, and easy to compare, they become convenient symbols for a much larger and more complicated concept.

Eventually, the symbol begins to carry more weight than the thing it was meant to represent.

This is where leanness starts to acquire a meaning that extends well beyond physiology. A lean physique becomes associated with discipline, control, work ethic, competence, and even personal worth. The difficulty of achieving it adds to its social value. If something is hard to obtain, then possessing it can be interpreted as evidence that the person has done something most people cannot or will not do. The body becomes a public demonstration of self-control.

That does not mean every desire to be lean is artificial, nor does it mean human beings have no evolved preferences concerning appearance. Physical traits can communicate information about age, strength, fertility, health, and capability, and those signals have always influenced attraction and status. But there is a large distance between finding a healthy, capable body appealing and believing that visible abs, extreme muscularity, or very low body fat represent some natural human ideal. Those standards are shaped heavily by culture, and modern fitness culture has become exceptionally effective at attaching status and identity to them.

If you removed the mirrors, photographs, social media, bodybuilding culture, comparison, and the knowledge that other people admired a lean physique, there is little reason to think the human organism would spontaneously decide that its abdominal muscles ought to become more visible. The body has no concept of a six-pack as an achievement. It responds to energy availability, movement, stress, recovery, and the environment it is trying to survive within.

That becomes especially apparent when someone tries to maintain a level of leanness that the body resists. Hunger increases. Food becomes more salient. Energy expenditure can decline. Recovery can worsen. Hormonal and reproductive function may begin to change. None of this means dieting is inherently unhealthy or that being lean is somehow unnatural. Human beings routinely tolerate discomfort in pursuit of things they value. The interesting part is that fitness culture often interprets the body's resistance to continued fat loss as evidence that the pursuit is becoming more admirable. The harder the condition is to maintain, the more discipline it appears to demonstrate.

Difficulty itself begins to create status.

This helps explain why extreme physiques can become so commercially powerful. They provide an immediate visual signal that appears to say something about the person before we know anything else about them. In some cases, the signal becomes even further separated from health when performance-enhancing drugs are used to create levels of muscularity and leanness that would be extraordinarily difficult to maintain naturally. The appearance may become more impressive at exactly the same time that the behaviors required to produce it create additional health risks. The image still communicates health because that is what the culture has taught people to see.

None of this requires rejecting leanness, bodybuilding, or aesthetic goals. Wanting to look a certain way is a perfectly legitimate preference. The problem begins when preference is disguised as biological necessity and appearance is allowed to stand in for a much broader definition of health.

We are not born wanting visible abs. We are born with drives for food, safety, movement, belonging, competence, reproduction, status, and connection. Culture can take those much older desires and attach them to a particular body, then convince us that obtaining the body will provide the things underneath it. The fitness industry is especially good at making that substitution because the body is visible, difficult to change, easy to compare, and easy to sell.

Leanness can be part of health. It can also be an aesthetic goal, a status symbol, an identity, or a commercial product. Problems arise when we stop distinguishing between those things.

Proximal-to-Distal Sequencing: How Force and Velocity Should Shape Athletic Training

Proximal-to-distal sequencing describes the way many athletic movements transfer kinetic energy through the body. In actions such as jumping, sprinting, throwing, kicking, or striking, the joints closer to the center of the body begin accelerating and reach peak angular velocity before the joints farther away. In the lower body, the hip reaches its peak angular velocity before the knee, and the knee before the ankle. As energy is transferred down the chain, the more distal segments reach progressively higher movement velocities.

This has an important implication for training because the different joints are operating in different parts of the force–velocity spectrum. The proximal segments move more slowly and are therefore more force-dominant, while the distal segments move progressively faster and become more velocity-dominant. In practical terms, this means the hip can often benefit substantially from heavy strength training because it plays a major role in generating the kinetic energy that is later transferred through the rest of the movement. The knee may require a more balanced mixture of force- and velocity-oriented work, while the ankle and calf, particularly in very fast movements, may benefit more from high-velocity and plyometric work than from large amounts of heavy strength training.

This also changes how exercise selection should be approached. Rather than treating an athlete as globally “force-dominant” or “velocity-dominant,” it can be more useful to examine where each joint sits within the movement sequence. An athlete may already produce plenty of force overall and still benefit from additional heavy hip training because the hip remains the slower, more force-oriented part of the sequence. Conversely, adding excessive strength work or muscle mass farther down the limb may offer little benefit when those distal segments are already operating at very high velocities. In cyclical movements such as sprinting, additional distal mass can also increase the cost of accelerating and decelerating the limb.

The same framework applies to the upper body. Throwing, punching, and striking rely heavily on force and energy generated through the hips and torso before that energy is passed into the arm. When an implement such as a bat, racket, or golf club is added, it effectively extends the sequence and makes more of the body relatively proximal, which can increase the usefulness of heavy strength training in areas that would otherwise sit closer to the velocity end of the chain. This is also why rotational strength deserves more attention: the torso is a highly proximal segment in many sporting actions, yet rotational training is often performed only with light, fast movements rather than stable, high-force exercises.

Fatigue is another important consideration because it can disrupt the sequence itself. When an athlete becomes fatigued, the normal timing between proximal and distal joints can deteriorate, with the joints beginning to accelerate and decelerate more simultaneously rather than passing energy efficiently from one segment to the next. This reduces performance and also changes the coordination pattern being practiced. If the goal is to improve the skill or speed of a movement, accumulating repetitions after the sequence has begun to deteriorate may no longer provide the same training effect.

A practical way to program around this for an athlete trying to improve jump performance would be to organize the session from the speed end back toward the force end while preserving the role each joint plays in the sequence. The athlete might begin with a small number of maximal countermovement jumps or calf hops while completely fresh, using the distal end of the chain at high velocity. That could be followed by a loaded jump variation to provide a more balanced knee-dominant stimulus, then heavier hip-dominant strength work such as hip thrusts and stiff-leg deadlifts to develop force production through the glutes and hamstrings. If the sport also requires resisting force through the torso, as in grappling, a good morning could be added to train hip extension while maintaining torso rigidity. The overall session would stay relatively low in volume so that the fast work remains fast and the heavier work does not create unnecessary fatigue that compromises later exposures.

The most useful takeaway is that athletic exercise selection should reflect where a joint sits in the kinetic sequence. Train the more proximal segments primarily for force, allow the middle of the chain to use a blend of force and velocity work, and bias the most distal segments toward high-velocity training when the sport demands very fast movement. At the same time, keep the athlete fresh enough during skill and speed work to preserve the proximal-to-distal sequence you are actually trying to improve.

How Often Should You Change Exercises?

Most training programs are built around fairly arbitrary blocks of time. You choose a group of exercises, perform them for four to six weeks, and then when the next phase begins, most or all of those exercises get replaced. There is nothing inherently wrong with organizing training into phases, and having some structure around when changes are made is certainly better than changing exercises whenever you feel like doing something different. The problem is that this approach assumes every exercise has roughly the same useful lifespan, when in practice some movements can continue producing progress for months while others seem to lose their return much sooner.

This is where exercise selection becomes a programming decision rather than simply a matter of choosing good movements. An exercise should remain in the program for as long as it continues doing what you need it to do. If performance is improving, execution remains consistent, the intended muscles are receiving the majority of the stress, and the exercise is not creating unnecessary joint or recovery problems, there is usually no compelling reason to remove it simply because you have reached the end of a predetermined training block. At the same time, an exercise does not need to become completely ineffective before another variation becomes the better choice. The goal of the next phase may change, a weak point may become more obvious, fatigue may begin accumulating in a particular joint or movement pattern, or another exercise may simply give you a better way to direct the training stress where you now want it.

The useful lifespan of an exercise is therefore individual to the movement, the person performing it, and the purpose it serves within the program. Time is part of that equation, but time alone tells us very little.

Upper-Body and Lower-Body Exercises Often Have Different Lifespans

One of the more useful distinctions when thinking about exercise rotation is that upper-body exercises generally benefit from more frequent variation than the major movements used for the lower body. This does not mean the upper body requires constant novelty or that lower-body exercises should remain unchanged indefinitely. It reflects the fact that the two areas give us different programming opportunities.

Consider how many meaningful ways an upper-body movement can be altered. A pressing exercise can change through bench angle, grip, implement, stability, range of motion, resistance profile, elbow position, or the path through which the arm moves. Rows, pulldowns, curls, extensions, and raises give us many of the same options. Relatively small changes can alter joint position, change the contribution of surrounding muscles, modify where the movement becomes difficult, or allow the target muscle to work through a slightly different range or line of pull.

For someone trying to develop a complete physique, those differences are useful. You can continue training the chest, shoulders, back, or arms while periodically changing how the load is distributed through those tissues. A low-incline dumbbell press, a converging machine press, and a barbell bench press all train many of the same structures, but they do not present the exact same mechanical problem. Rotating between them can allow you to continue developing the same general musculature while shifting emphasis toward whatever the current phase of training requires.

Lower-body training tends to be organized around fewer fundamental patterns. Most productive programs will contain some combination of squatting, hinging, lunging, stepping, knee flexion, and knee extension, and the major compound movements within those categories are capable of tolerating a considerable amount of progressive loading. A squat or Romanian deadlift can often remain useful for a long time because there is still plenty of room to improve force production, technical efficiency, load tolerance, and overall execution without needing to continually alter the exercise itself.

There are also fewer small positional changes that completely redirect the training effect. Foot position, stance width, bar placement, implement choice, and range of motion certainly influence lower-body exercises, and those changes can be valuable, but lower-body progression is often driven to a greater extent by becoming stronger and more competent within the same large movement pattern. If someone is still adding load or repetitions to a Romanian deadlift while maintaining excellent execution and continuing to load the hamstrings effectively, there may be very little gained by replacing it simply because six weeks have passed.

Lower-body variations become especially useful when there is a reason for them. A front squat may be selected to place greater demand on the knee extensors or reduce the absolute loading required compared with a back squat. A different deadlift variation may be introduced to address a weakness, manage fatigue, change the range through which force must be produced, or better match the objective of the next training phase. The movement changes because the problem we are trying to solve has changed.

Exercise Variety Is Only One Way to Change the Training Stimulus

Exercise rotation is often treated as though it is the primary way to prevent training from becoming repetitive, but the exercise itself is only one variable inside a much larger program. You can keep the same movement in place while meaningfully changing the demand through load, repetitions, volume, tempo, rest periods, frequency, proximity to failure, or the way the exercise is paired with other movements.

A squat performed for sets of ten with moderate loads creates a different training experience from the same squat performed several weeks later for sets of four or five with considerably more weight. The motor pattern remains familiar, which allows the lifter to continue benefiting from the technical skill they have developed, while the physiological and mechanical demands of the program move in a different direction. This is one reason lower-body exercises can often remain in a program longer without the training stimulus becoming completely stagnant.

The distinction is important because people frequently change the exercise when what actually needed to change was the way the exercise was being programmed. If a movement is still mechanically appropriate, well tolerated, and capable of being progressed, modifying the loading parameters may give you everything you need from the next phase without sacrificing the technical development that has already taken place.

There will eventually be a point where changing the exercise itself becomes useful, but that decision should come from what the program is trying to accomplish rather than from an assumption that novelty automatically produces better adaptation.

Exercise Changes Should Have a Reason Behind Them

When looking through a program, you should be able to explain why each exercise is there and why it replaced whatever came before it. Sometimes the explanation is straightforward: performance on the previous exercise has stopped progressing despite appropriate recovery and effort. Other times the change is made because a joint is becoming irritated, because another muscle consistently becomes the limiting factor before the target tissue has received enough work, or because a different movement provides a better mechanical fit for the next objective.

Weak-point training is a good example. If a lifter's squat is being limited by quadriceps strength, choosing a squat variation that increases the demand on the quadriceps may help address the bottleneck that is limiting the larger movement. The same logic applies to hypertrophy. If someone wants to develop their chest but a particular press consistently becomes limited by the triceps or anterior deltoid, changing the angle, implement, stability requirements, or resistance profile may allow the chest to become the limiting tissue again.

This is a very different use of variety from simply cycling through exercises to keep training interesting. Variety becomes productive when it gives the body a reason to adapt in a direction that supports the larger goal of the program.

Training Experience Changes How Frequently Variation Is Useful

Training age also has to be considered because a beginner and an advanced lifter are not responding to the same training problem. Someone who has only been lifting for a short period is still learning how to perform the exercises, coordinate force through the movement, recognize what productive effort feels like, and develop the basic strength required to make the movement worth loading aggressively. Repeated exposure is extremely valuable during this stage because every session is giving them an opportunity to become better at performing the exercise itself.

Constantly changing movements can interfere with that process. If a beginner performs a different squat variation every two weeks, it becomes difficult to separate actual physical improvement from changes in familiarity with each exercise. Keeping the basic movements relatively stable for six to eight weeks, and sometimes considerably longer, gives them enough exposure to learn the movement and demonstrate whether they are actually becoming stronger.

As training experience increases, the situation gradually changes. An advanced lifter has already accumulated years of exposure to many of the same movement patterns, their technique is more established, and familiar exercises no longer provide the same degree of novelty they once did. Certain movements may therefore only need to remain in the program for two to four weeks before another variation offers a more useful stimulus, while other exercises may continue producing for much longer.

Those timeframes should be treated as general guidelines rather than rules. Training intensity, total volume, recovery ability, exercise complexity, joint tolerance, technical proficiency, and individual response all influence how long a particular exercise remains useful. Someone aggressively loading an exercise several times per week may exhaust its productive window sooner than someone using the same movement at a lower frequency and with more conservative loading.

The more experienced the lifter becomes, the more this judgment becomes part of programming. There is less value in blindly following a predetermined exercise calendar and more value in understanding what each movement is currently contributing.

Managing the Rate of Change

The body adapts to repeated exposure, and that adaptation is exactly what we are trying to create through training. During the early stages of using an exercise, repeated exposure improves coordination, strength, technical efficiency, and the ability to tolerate greater levels of work. Over time, however, the return from presenting the exact same problem begins to diminish, particularly when the loading conditions surrounding the movement remain unchanged.

Programming requires managing that process without rushing it.

Changing exercises too quickly removes the opportunity to accumulate meaningful practice and progression. You never become sufficiently skilled at the movement, and you may spend most of your training repeatedly adapting to new exercises rather than becoming stronger within them. Keeping everything unchanged for too long creates the opposite problem, where training continues to repeat a demand that may no longer provide enough of a reason for further adaptation.

There is no universal number of weeks that resolves this problem. Upper-body and lower-body movements frequently deserve different rates of change, beginners and advanced lifters require different amounts of repetition, and the same exercise can have very different productive lifespans depending on how it is being programmed.

Learning to recognize those differences is one of the skills that separates following a workout from understanding how training is actually organized. A movement deserves to stay in the program while it continues contributing to the adaptation you are trying to create. When its return begins to diminish, or when another exercise gives you a better way to address the next problem, the program should move with it.

Food Is More Than Fuel: How What We Eat May Help Tell the Body Where and When It Is

We usually talk about food in terms of calories, macronutrients, vitamins, minerals, and the raw materials required to keep the body functioning. Protein provides amino acids, carbohydrates provide glucose, fats provide fatty acids, and all of these can eventually be used to support energy production, tissue repair, hormone synthesis, and the thousands of biochemical reactions occurring throughout the body at any given moment.

That is all true, but it leaves out something I think is becoming increasingly important to how we understand health. Food does more than supply material and energy. It also changes the physiological state of the organism consuming it. Different foods alter hormones, enzymes, cellular signaling pathways, mitochondrial activity, redox balance, gene expression, and even the peripheral biological clocks found throughout tissues such as the liver, skeletal muscle, pancreas, and adipose tissue.

Seen through that lens, food can also be understood as information.

That idea becomes more interesting when we consider that human beings did not evolve in an environment where food, light, temperature, movement, and season existed as independent variables. They changed together. The amount of daylight changed with the seasons. Temperature changed with the seasons. The plants that were available, the amount of carbohydrate in the environment, and the amount of energy required to survive all changed along with them.

Modern life allows us to separate nearly all of those things.

We can experience a short winter day while sitting in a climate-controlled room, remain under artificial light well into the biological night, move very little, and eat foods grown thousands of miles away in an entirely different light and temperature environment. I do not think we currently have enough evidence to say exactly what the physiological consequences of every one of these mismatches are, but I do think there is a reasonable question hiding underneath them: how much of health depends on the different signals reaching the body telling a coherent story?

The Body Is Constantly Reading Its Environment

Light is the most obvious example because its relationship with circadian biology is well established. Light entering the eyes helps synchronize the central circadian clock in the brain, which in turn helps organize sleep and wakefulness, hormone secretion, body temperature, metabolic activity, and many of the other processes that follow a roughly 24-hour rhythm.

The central clock is only part of this system. Tissues throughout the body contain their own circadian machinery, and these peripheral clocks respond to more than light alone. Meal timing, physical activity, temperature, and metabolic state all contribute to the timing and organization of physiology.

This means the body is continually integrating information from several directions at once. Light provides information about time of day. Temperature provides information about the physical environment. Movement provides information about energetic demand. Food provides information about nutrient availability and alters the metabolic state of the tissues receiving it.

These signals historically occurred in patterns that were largely predictable. Morning light was accompanied by waking and movement. Darkness was accompanied by rest. Seasonal changes in daylight and temperature influenced the foods available in the local environment. Biology evolved inside those relationships.

I think this is where the conversation around food becomes much more interesting than simply asking how many calories it contains.

Different Fuels Create Different Metabolic Conditions

Carbohydrate and fat can both be used to generate ATP, but they do not travel through metabolism in exactly the same way. Once we follow those fuels into the mitochondria, the differences become more obvious.

Carbohydrate metabolism produces NADH through glycolysis and the citric acid cycle, which the cell then uses to help generate energy. Fatty acids are broken down through beta oxidation, which produces both NADH and FAD-related energy carriers. The key point is that carbohydrates and fats feed into energy production in slightly different ways, even though both ultimately help the body make ATP.

The important point for this discussion is that the body does not simply see “energy” arriving. The form in which that energy arrives influences how electrons enter mitochondrial respiration, how the proton gradient is generated, how much oxygen is consumed, how much ATP can be produced, and what the surrounding redox environment looks like.

Fat and carbohydrate therefore create somewhat different metabolic conditions even when both ultimately contribute to ATP production.

This becomes even more interesting when we look beyond energy production itself. NAD is a molecule the body uses to help manage energy and keep cells running properly. Its balance in the cell reflects how much energy is available and how “stressed” or active the cell is. It also seems to play a role in timing systems in the body, helping coordinate things like metabolism, repair, and daily biological rhythms.

Food composition therefore has the potential to influence physiology at several levels simultaneously. It provides substrate, changes hormonal signaling, alters mitochondrial fuel selection, changes redox conditions, and interacts with biological timing systems.

This is where I think the phrase “food is information” starts to become more than a metaphor.

Food Carries a History of the Environment That Produced It

There is another layer to this that I find particularly interesting.

Plants are products of their environment. Light intensity, photoperiod, temperature, water availability, soil conditions, stress, and season all influence how a plant grows and what compounds it produces. The food that eventually reaches us is therefore partly a biochemical expression of the conditions in which it was grown.

That doesn’t mean a tomato carries a code about where it was grown. We don’t have evidence for anything like that.

Still, it’s worth asking whether the chemistry and availability of food have always been part of the broader environment people lived in.

For most of human history, the foods available in a particular place were constrained by the conditions of that place. Long summer days, warmer temperatures, and greater plant growth tended to coincide with greater carbohydrate availability. Shorter days and colder temperatures changed the food environment and, depending on geography, could shift the diet toward stored foods, animal foods, and different macronutrient proportions.

The light environment and the food environment were therefore connected even if food itself was not functioning as some kind of direct photoreceptor.

Sunlight shaped the environment. The environment shaped the food. The food shaped human metabolism.

That chain alone gives us plenty to think about.

Modern Life Allows the Signals to Separate

One of the unusual features of modern life is that we can now experience combinations of environmental signals that would have been difficult or impossible to create for most of human history.

We can eat tropical fruit in the middle of a northern winter. We can consume food at midnight under bright artificial lighting. We can live in darkness during the day and expose ourselves to strong light at night. We can remain at a comfortable indoor temperature regardless of season. We can consume a continuous abundance of carbohydrate and fat while doing almost no physical work.

None of these observations proves that any single modern behavior is inherently harmful. The larger issue is that they allow the timing and relationships between biological signals to drift apart.

Light may be telling the central nervous system one thing while meal timing is telling peripheral tissues something else. Temperature may suggest one environment while food availability reflects another. Energy intake may signal abundance while physical activity signals almost no demand for that energy.

This is where I think the concept of biological synchronization becomes useful.

Health depends on the body coordinating an enormous number of processes at once. Energy has to be produced, tissues have to be repaired, damaged proteins have to be cleared, immune activity has to activate and resolve, hormones have to rise and fall, and metabolic pathways have to respond appropriately to changing conditions.

The body does not need those processes to remain constant. It needs them to remain organized.

Training provides a good example. A hard workout temporarily disrupts homeostasis. Energy stores fall, tissue is stressed, inflammatory signaling increases, and fatigue accumulates. None of that is inherently unhealthy. If the system has enough capacity to recover, the disturbance is resolved and the organism can return in a more capable state.

Problems begin when disruption continually outpaces resolution.

The same framework may apply more broadly to health. Poor sleep, circadian disruption, chronic psychological stress, excessive energy intake, insufficient movement, and repeated environmental mismatch may all create demands that the organism has to continually compensate for. Over time, health declines as more of the system's resources are spent managing unresolved problems rather than building and maintaining capacity.

Where Local and Seasonal Food May Fit

This is where my own interest in local and seasonal food comes in.

I am not making a strong claim that we fully understand all the mechanisms at play here, or that the science has already mapped out every possible interaction between food, environment, and physiology. My sense is simply that there are multiple overlapping systems involved, and we may not yet have a complete picture of how they integrate.

What I do think is reasonable is that eating foods produced within the environment and season you currently inhabit tends to preserve some of the relationships that shaped human biology in the first place.

Local food reflects local growing conditions. Seasonal food reflects the time of year. Both tend to reconnect food availability with the light, temperature, and environmental conditions occurring around the person eating it.

I also want to be careful not to overstate certainty about mechanisms here. I am not claiming that we already know exactly how these relationships translate into health outcomes, whether through circadian biology, mitochondrial metabolism, gut signaling, plant chemistry, or some combination of factors. My interest is more in acknowledging that modern nutrition often treats food as if its geographic and environmental context is irrelevant, even though that context is part of how food comes into existence.

I am not convinced that it is irrelevant.

If the human organism is constantly using environmental information to organize physiology, then it seems reasonable to ask whether the food environment should be considered part of that information system rather than simply a collection of calories and nutrients.

At the very least, the question pushes us toward a broader understanding of nutrition.

Food contains energy. It contains nutrients. It alters hormones and cellular signaling. It changes mitochondrial substrate use and redox state. It influences peripheral clocks. It is also produced by an environment whose light, temperature, soil, water, and season influence what that food becomes.

Those layers do not have to compete with one another. They are different levels of the same biological conversation.

The question I keep coming back to is whether health improves when those conversations remain coherent.

If light, food, movement, temperature, sleep, and season historically changed together, then perhaps part of maintaining health is preserving enough of that relationship for the body to accurately organize itself around the environment it actually inhabits.

That idea is still partly hypothesis, but it is a hypothesis I think is worth taking seriously.

Speed: What Actually Makes Someone Faster

Speed is produced by several underlying adaptations, and each requires a different type of stimulus.

Coordination is one of the most specific. To improve the coordination of a fast movement, that movement has to be practiced quickly. Slow practice does not fully develop the motor program required at maximal velocity. This is why sprinting, jumping, throwing, or other high-speed tasks need to be performed at or near the speed the athlete is trying to improve.

The quality of each repetition matters. Once fatigue causes the athlete to slow down, the training stimulus changes. High-velocity work therefore does not need to follow traditional high-volume set-and-rep structures. A small number of maximal-quality repetitions may be more useful than continuing after velocity has fallen.

Motor-unit recruitment is different because it is primarily muscle-specific rather than movement-specific. Heavy strength training and brief maximal isometrics can improve recruitment and contribute to faster performance even though those exercises are not performed at maximal velocity.

Other adaptations, however, require actual fast movement. Increased motor-unit firing rates and increased muscle-fiber shortening velocity do not appear to develop from heavy strength training alone. They require genuinely high movement speeds. Maximal intent with a slowly moving heavy load is therefore not a substitute for fast training.

Strength work can also interfere with speed when poorly managed. Excessive fatigue can promote shifts toward slower muscle-fiber characteristics, and unnecessary hypertrophy can add mass that the athlete then has to accelerate and decelerate. This is especially relevant when muscle is added distally rather than around the hips.

Actionable takeaway: Train speed through three main targets: practice the actual fast movement for coordination, use heavy work or brief isometrics to improve transferable recruitment, and include genuinely maximal-velocity work to improve firing rate and shortening velocity. Stop the work when speed begins to fall.

Maximum Strength: What Actually Makes Someone Stronger

Maximum strength can improve through several different adaptations, and those adaptations do not all transfer equally to other movements.

Coordination is one contributor. Repeated practice can make an exercise more efficient, allowing someone to lift more weight without necessarily increasing the force-producing capacity of the muscle itself. This type of improvement is highly specific to the movement and even to the load being used. Becoming more skilled at a heavy squat is therefore very useful for a powerlifter, but that coordination does not automatically transfer to sprinting or jumping.

Motor-unit recruitment is much more transferable. Improving the nervous system’s ability to activate more of a muscle increases the force that muscle can produce across different movements that use it. High recruitment can be trained through heavy lifting, brief maximal isometrics, and other high-effort contractions, provided fatigue and discomfort are kept low enough to allow high central motor command.

Hypertrophy contributes by increasing the amount of contractile tissue available to produce force. For athletes, however, the location of that muscle matters. Adding muscle where it contributes to the demands of the sport can be useful, while adding mass indiscriminately may not be.

Other adaptations can also contribute. Reduced antagonist co-activation can increase net force around a joint. Lateral force transmission can improve how efficiently muscle-fiber force reaches the tendon. Increased tendon stiffness can improve force production in slow, high-force actions by changing how quickly the muscle fibers themselves have to shorten.

The important point is that the same improvement in a strength test can come from very different mechanisms.

Actionable takeaway: Do not treat “getting stronger” as one process. Identify whether the goal is movement skill, greater muscle activation, more muscle, or another force-producing adaptation, and program specifically for that need.

Strength, Speed, and Power: Understanding the Relationship

Strength, speed, and power are performance outcomes. They are things we measure, not single adaptations that the body develops directly.

An increase in strength might come from greater muscle size, improved motor-unit recruitment, better coordination, changes in tendon behavior, or other adaptations. Speed works the same way. A faster sprint, jump, or throw tells us performance improved, but the useful question is what changed underneath that performance.

Power sits one level higher because it is the product of force and velocity. That means transferable power is improved by increasing force capability, velocity capability, or both. This is important because the load that produces the highest measured power in a gym exercise is not necessarily the load that best develops either quality. Heavy loading is better suited to high-force adaptations, while very light or unloaded movements performed at genuinely high speeds are better suited to high-velocity adaptations.

Strength also does not automatically become speed. The force a muscle can produce decreases as shortening velocity increases, so an athlete can be very strong at slow speeds while still lacking the ability to produce force at high velocities. Likewise, intending to move a heavy load quickly is not the same as actually moving quickly. Speed-specific adaptations require exposure to genuinely fast movement.

Fatigue therefore matters because it can reduce the athlete’s ability to reach the velocities required for speed development. High-velocity work should be performed while the athlete is fresh enough to actually express speed.

Actionable takeaway: Decide whether you, or the athlete, primarily needs more force, more speed, or both. Train those qualities directly and protect the quality of the stimulus by limiting unnecessary fatigue.

Cardio and Lifting: How to Do Both Without Killing Your Progress

There is an old idea in strength training that cardio kills your gains. Like most absolutes in fitness, it takes something that can happen under certain conditions and turns it into a rule that supposedly applies to everyone. Cardio does not automatically prevent you from getting stronger or building muscle, and for most people there is no reason they cannot improve their cardiovascular fitness while continuing to make progress in the weight room. The problem begins when the cardio you are doing creates enough fatigue, muscular stress, or recovery demand that it starts compromising the lifting responsible for the result you actually care about.

This is why the first question should not be whether cardio is good or bad for muscle growth. The better question is why you are doing cardio in the first place. Someone walking to increase energy expenditure during a fat-loss phase, someone doing moderate aerobic work for cardiovascular health, and someone preparing for a marathon are all technically “doing cardio,” but they are solving completely different problems. The purpose of the cardio should determine the modality, frequency, intensity, and amount you use, as well as how much of your recovery you are willing to dedicate to it.

Why Are You Doing Cardio?

For someone primarily focused on body composition, cardio is usually a tool for increasing activity and energy expenditure. In that situation, there is very little reason to immediately choose the hardest form available. Daily walking, incline treadmill work, easy cycling, or other low-intensity activity can increase expenditure while creating relatively little additional fatigue. For some people, simply increasing daily steps will accomplish what they need. If more activity is necessary, adding 20–30 minutes of low-intensity cardio after lifting sessions is a reasonable place to start and can be increased only when the goal actually requires it.

Cardio for general health serves a different purpose. Here the objective is to improve cardiovascular fitness and aerobic capacity rather than simply burn additional calories. Regular moderate aerobic work that can be repeated and recovered from makes sense, and something in the range of 20–40 minutes two or three times per week can be a practical starting point. This work does not need to become another maximal training session. HIIT can have a place, but harder work is not automatically more useful when the desired adaptation can be achieved with a lower recovery cost.

Endurance performance changes the conversation again because specificity now matters. If you want to become a better runner, you eventually have to run enough to improve at running. If you are preparing for a marathon, the volume, frequency, and specificity of the endurance work have to become large enough to drive those adaptations. At that point, cardio is no longer simply supporting your lifting program; it has become one of the primary goals of the training phase. Some reduction in the rate of hypertrophy may come with that shift, but that is not necessarily a programming mistake. It is the predictable cost of prioritizing a different quality.

Where the Interference Actually Comes From

Combining resistance training and endurance work is commonly referred to as concurrent training, and the potential reduction in strength or hypertrophy adaptations is usually called the interference effect. This has often been interpreted to mean that cardio somehow burns muscle or shuts down muscle growth, but that is an overly dramatic way to describe what is usually a much simpler problem. Concurrent training generally does not appear to produce a large reduction in whole-muscle hypertrophy under normal conditions, although some forms of aerobic work seem to create more interference than others. The practical issue is usually the total amount of stress being accumulated and whether the person can continue recovering well enough to train productively.

Three variables are especially useful when thinking about that stress: frequency, intensity, and modality. The more often you perform cardio, the harder those sessions are, and the more muscular damage or impact the modality creates, the more likely it is to compete with the resistance training you are trying to prioritize. There is no universal number of sessions where cardio suddenly becomes excessive because recovery capacity differs from person to person. Someone sleeping well, eating enough, and performing relatively low-fatigue aerobic work may tolerate a considerable amount. Someone dieting aggressively, training legs hard several times per week, sleeping poorly, and adding frequent running sessions may reach their limit much sooner.

Intensity changes the cost of the work considerably. Walking, incline treadmill work, and easy cycling generally create relatively little fatigue, which is why they can usually be performed more frequently. Hard intervals and sprint work are different. They may be more time-efficient, but they also create a larger recovery demand and overlap more heavily with the high-intensity muscular work already being performed in the weight room. If the purpose of cardio is simply to increase energy expenditure during a body-composition phase, turning every session into HIIT often creates more fatigue than the goal requires.

Modality matters for the same reason. Walking and cycling generally create less impact and eccentric muscular stress than running. Running is not inherently bad for hypertrophy, but it tends to be more expensive from a recovery standpoint, particularly as volume and intensity rise. If someone is preparing for a race, that cost is necessary because running is the adaptation being pursued. If someone is simply trying to burn a few extra calories while maximizing lower-body hypertrophy, choosing a lower-cost modality is usually the more sensible option. The principle is simple: use the least costly tool that still accomplishes the job.

The Mechanism Is Probably Less Complicated Than It Sounds

A great deal of discussion around concurrent training has focused on molecular signaling. One of the better-known explanations was that endurance exercise activates AMPK and other signaling pathways associated with aerobic adaptation, which could suppress mTOR signaling and interfere with the muscle-building response to resistance training. That explanation is interesting, but the evidence has not supported such a clean relationship. Aerobic and resistance exercise can be performed in relatively close proximity without necessarily producing the kind of suppression of anabolic signaling that the original hypothesis predicted.

There are other molecular explanations that remain possible, but from a coaching standpoint there is a much simpler explanation that matters more: fatigue reduces what you are able to do in the gym. Resistance training needs to provide enough tension and effort to stimulate the muscle fibers you are trying to grow. If hard cardio leaves you fatigued before your next lifting session, you may use less weight, perform fewer reps, produce less force, or struggle to recruit the same high-threshold motor units you otherwise could. An isolated bad workout does not matter much, but if cardio repeatedly reduces the quality of the resistance-training stimulus, the accumulated result can be less hypertrophy than you would have achieved otherwise.

That is the useful way to think about the interference effect. Cardio does not have to directly destroy muscle to interfere with muscle growth. It simply has to make the training responsible for building that muscle consistently worse.

If Muscle Is the Goal, Protect the Lifting

Once the priority is clear, the order of training becomes fairly straightforward. If size and strength are the primary goals, lifting should receive the best of your energy and recovery. That generally means resistance training comes first when lifting and cardio need to happen on the same day. Low-intensity work can often be performed immediately afterward because it creates relatively little additional fatigue. If the cardio session is harder, separating the two sessions by several hours can be useful so there is time to eat, hydrate, and regain some performance capacity before training again.

The exact number of hours is not magical. Something around three to six hours is a reasonable practical guideline when the second session is more demanding, but the larger principle is simply to avoid asking the body to perform two difficult sessions back-to-back when there is no need to do so. If the goal is hypertrophy, the resistance-training session is the one you want to protect.

There is also a difference between separating training sessions and separating training days. Coaches sometimes alternate lifting and cardio throughout the week because it appears to create more recovery between each type of training. In reality, this can leave the same muscles working almost every day. A lower-body session on Monday, running on Tuesday, another leg workout Wednesday, and more conditioning Thursday technically separates the modalities while providing very little actual recovery for the legs.

In many cases, it makes more sense to consolidate the stressors. Place cardio on the same days as lifting when appropriate, perform the lifting first, and then leave complete recovery days afterward. This concentrates the workload into fewer days and gives the muscles and nervous system longer uninterrupted periods to recover. For someone whose main goal is hypertrophy, that can be a much cleaner way to organize concurrent training than spreading some form of lower-body stress across the entire week.

How Much Cardio Should You Actually Do?

There is no single cardio prescription because the amount should come from the goal rather than from the belief that more exercise is automatically better. If body composition is the priority, start with daily movement and use steps as the first lever. If additional expenditure is needed, add 20–30 minutes of low-intensity work after lifting sessions and assess what happens before doing more. If fat loss is already progressing at the desired rate, adding more cardio simply because it is available does not accomplish anything useful.

For general health, the goal is to establish a consistent aerobic base that complements resistance training. Moderate aerobic sessions a few times per week are enough to provide meaningful cardiovascular work for many people without turning the entire program into conditioning. Higher-intensity intervals can be added if there is a reason for them, but they should not automatically replace lower-intensity work simply because they feel more difficult.

For endurance performance, the required amount becomes much more specific to the event. More running, cycling, intervals, or longer sessions may be necessary, and eventually that increased workload has to be reflected elsewhere in the program. Resistance-training volume may need to come down, lower-body training may need to be reorganized, and expectations for hypertrophy may need to change during that phase. Training resources are finite, so increasing the priority of one quality inevitably changes how much can be invested in another.

You Can Improve Both, but One Has to Take Priority

This is ultimately the part of concurrent training that people tend to avoid. You can improve multiple qualities at the same time, but you cannot assume that every quality can be maximized simultaneously. If bodybuilding is the goal, lifting should drive the program and cardio should support body composition, health, or conditioning without consistently compromising resistance-training performance. If you decide to prepare for a marathon, endurance training becomes the primary focus and hypertrophy takes a secondary role for that period.

Neither choice is better. They simply require different programs. The problem begins when someone says muscle growth is the priority while training like an endurance athlete, or says endurance performance is the priority while refusing to give it enough training volume because they are afraid of sacrificing any hypertrophy. The goal has to determine what receives the majority of your time, effort, and recovery.

The simplest way to know whether you have found the right balance is to watch the thing you are trying to protect. If your loads, repetitions, execution, and recovery continue improving while cardio is in the program, there is little reason to assume the cardio is meaningfully interfering. If your legs are constantly fatigued, performance begins to fall, soreness never resolves, or progression stalls after cardio volume increases, the dose has probably exceeded what you can currently recover from. At that point, reduce the frequency, lower the intensity, choose a less demanding modality, reorganize the week, or improve the recovery supporting the training.

Cardio and lifting are not natural enemies. The problem is usually trying to do more work than the goal requires or more work than the athlete can recover from. Determine why the cardio is there, choose the modality that accomplishes that goal with the lowest necessary recovery cost, give the priority training the best of your performance, and adjust the total dose according to what your body is actually showing you. You can improve both cardiovascular fitness and muscle mass. You simply have to be clear about which one leads when the demands begin to compete.

P&G Bought Thorne. Here’s Why I’d Start Looking Elsewhere

I’ve used Thorne supplements for years, and I still think they’ve been a very good company. Their reputation was earned through strong formulations, quality standards, testing, and credibility with health professionals.

But this week, Procter & Gamble agreed to acquire Thorne for $3.8 billion.

That acquisition is worth paying attention to.

In 2023, private-equity firm L Catterton purchased Thorne for approximately $680 million and took the company private. Less than three years later, it’s being sold to P&G for $3.8 billion. During that time, Thorne has continued growing, with sales reportedly expected to reach roughly $650 million this year.

In other words, P&G isn’t buying a struggling supplement company that needs to be fixed.

It’s buying a successful premium wellness brand.

And arguably, the most valuable thing it’s buying isn’t the capsules in the bottles. It’s the credibility Thorne spent decades building.

That’s becoming increasingly valuable to companies like P&G as consumers spend more money on health, prevention, supplements, and premium wellness products. Rather than building that trust from scratch, a large consumer company can simply acquire a brand that already has it. P&G already owns supplement and wellness brands including New Chapter, Align and Metamucil, and the Thorne acquisition represents a much larger push into the category.

The problem is that ownership transfers immediately. Trust doesn’t.

Nothing about this acquisition means the Thorne products sitting on the shelf suddenly became worse. And there’s currently no evidence that P&G has plans to reduce ingredient quality, changed formulations, or lower Thorne’s manufacturing standards.

My concern is what happens over time.

When a company spends $3.8 billion on an acquisition, that investment eventually has to produce a return. Growth, margins, distribution, manufacturing costs, ingredient costs and product profitability all become part of the equation.

That doesn’t guarantee Thorne’s quality will decline. But it does change the incentives surrounding the brand.

And when the reason I was willing to pay a premium for Thorne in the first place was its reputation for quality, that’s enough for me to start considering alternatives rather than waiting to find out what changes under new ownership.

So, What Should You Look For Instead?

If you decide to move away from Thorne, the goal should be to find a company that still prioritizes the same things that made Thorne worth using in the first place: quality ingredients, strong formulations, reliable manufacturing, and meaningful testing.

That’s one reason I’ve used NutriDyn alongside Thorne for years.

NutriDyn is a smaller, pharmacedical grade, practitioner-focused supplement company with a strong emphasis on formulation, manufacturing standards, ingredient quality, and third-party testing. More importantly, they already make alternatives to many of the Thorne products I’ve commonly used and recommended.

So rather than telling people to stop using Thorne without giving them somewhere to go, I put together a simple Thorne → NutriDyn replacement guide with comparable options for many of Thorne’s most popular supplements.

Thorne Formula	NutriDyn Replacement
5-Hydroxytryptophan	5-HTP 5-HTP Extra Strength
5-MTHF 1 mg	Methyl Complete Methyl Support
5-MTHF 5 mg	Methyl Complete Methyl Support
5-MTHF 15 mg	Methyl Complete Methyl Support
Acetyl-L-Carnitine (formerly Carnityl)	Acetyl-L-Carnitine
Adrenal Cortex	Stress Essentials Adrenal Renew
Advanced Bone Support (formerly Oscap)	Bone Support Bone Support Chewable Bone Support Extra Strength Bone Support Prime Bone Support Vegetarian Bone Support with Magnesium
Advanced DHA	Omega Pure DHA 600
Advanced Digestive Enzymes - (formerly Bio-Gest)	Digestive Complete
Advanced Nutrients	Essential Multi or Essential Multi with Iron
Alpha-Lipoic Acid	Alpha-Lipoic Acid
Amino Complex - Berry	Performance Drink
Amino Complex - Lemon	Performance Drink
Arabinex	GI Integrity GI Restore
Ascorbic Acid (60 count)	Vitamin C 1000 Vitamin C 1000 Complex Vitamin C 500 Bio Complex
B-Complex #12	B-Complex
B-Complex #6	B-Complex
Bacillus Coagulans	UltraBiotic Spore Probio or UltraBiotic Daily Multi-Strain
Basic B Complex	B-Complex
Basic Nutrients 2/Day	Essential Multi or Essential Multi with Iron
Basic Nutrients 2/Day - NSF Certified for Sport	N/A, consider: Essential Multi or Essential Multi with Iron
Basic Prenatal	Prenatal or Everyday Essentials Pregnancy
Berbercap	Berberine Pro
Berberine (formerly Berberine-500)	Berberine Pro
Beta Alanine-SR	Performance Drink
Betaine HCL & Pepsin (225's)	HCl Support
Betaine HCL & Pepsin (450's)	HCl Support
BioMins	Essential Minerals
BioMins II	Essential Minerals
Biotin	N/A, consider: Hair, Skin, & Nails
Blood Sugar Support Bundle	N/A
Bone Support Bundle	N/A
Boswellia Phytosome	N/A
Brain Factors	Brain Restore Brain Support
Bromelain	Bromelain 1400 Bromezyme®
Buffered C Powder	C Aspa Scorb®
Cal-Mag Citrate + Vitamin C	Cal Mag 750 Cal-Mag Crystals
Calcium D-Glucarate	Calcium D-Glucarate Plus
Calcium-Magnesium Malate	N/A
Catalyte	Hydrate
Choleast-900	Cardio Essentials Red Yeast Rice
Chromium Picolinate	Chromium Picolinate Chromium Picolinate 500™
Collagen Fit	Multi Collagen Collagen Renew
Collagen Plus	Multi Collagen Collagen Renew
Copper Bisglycinate	N/A
CoQ10 (formerly Q-Best 100)	CoQ10 100 mg CoQ10 200 mg CoQ10 Ubiquinol
Cortrex	Stress Essentials Adrenal Renew
Craving and Stress Support (formerly Relora Plus)	Neuro Balance
Creatine	Creatine Powder
Crucera-SGS	Sulforaphane Complex
Curcumin Phytosome (formerly Meriva)	Curcumin 400x Curcumin BCM-95®
Curcumin Phytosome - Certified for Sport (fomerly Meriva)	Curcumin 400x Curcumin BCM-95®
Curcumin Phytosome - Sustained Release (formerly Meriva)	Curcumin 400x Curcumin BCM-95®
Daily Greens Plus	NutriDyn Fruits & Greens NutriDyn Fruits & Greens Immune Support NutriDyn Fruits & Greens TO GO NutriDyn Fruits & Greens TO GO - Starter Kit NutriDyn Fruits & Greens TO GO with Monk Fruit NutriDyn Fruits & Greens with Monk Fruit NutriDyn Kids Fruits & Greens NutriDyn Shaker Cup - 20oz
Diabenil	Gluco IR
DiCalcium Malate	N/A
DIM Advantage	I-3-C Plus
Dipan-9	Aprozyme
Emotion Balance Support (formerly Deproloft-HF)	Neuro Balance
Energy Bundle	N/A
EnteroMend	GI Integrity
Ferrasorb	Iron Support
Fertility Bundle	N/A
FiberMend	GI Integrity
FloraMend Prime Probiotic	UltraBiotic Complete UltraBiotic Daily Multi-Strain
FloraPro-LP Probiotic	UltraBiotic Complete UltraBiotic Daily Multi-Strain
FloraSport 20B	UltraBiotic Complete UltraBiotic Daily Multi-Strain
Foundational Bundle	Everyday Essentials Foundation Everyday Essentials Active Everyday Essentials Men's Everyday Essentials Women's Everyday Essentials Women's Advanced
GI Relief (formerly GI-Encap)	GI Integrity
Glucosamine & Chondroitin	Chondro-Relief® Chondro-Relief® Intensive Care Chondro-Relief® Plus Chondro-Relief® Vegetarian
Glucosamine Sulfate	N/A
Glutathione-SR	Liposomal Glutathione L-Glutathione
Glycine	Pure Glycine
Grape Seed Extract (formerly O.P.C.-100)	N/A, consider: Pro-Antho Forte™
Green Tea Phytosome	N/A
Gut Health Bundle	N/A, consider:
Healthy Aging Bundle	N/A
Healthy Lipids Bundle	Cardio Essentials Cholestin Support
Heart Health Complex (formerly Q-10 Plus)	N/A
Hemp Oil +	N/A
Immune Support Bundle	N/A, consider::
Iodine & Tyrosine	Thyro Complex® Thyroid Complex
Iron Bisglycinate	Iron Support
Joint Support Bundle	Chondro Jointaide
Joint Support Nutrients (formerly AR-Encap)	Chondro Jointaide
Kids Multi +	Kids Chewable Multi
L-Arginine - Sustained Release (formerly Perfusia-SR)	Pure L-Arginine HCl
L-Arginine Plus (formerly Perfusia Plus)	Cardio Flow
L-Carnitine	L-Carnitine 500
L-Glutamine	L-Glutamine Powder
L-Glutamine Powder	L-Glutamine Powder
L-Tyrosine	L-Tyrosine
Liver Cleanse	Detox Dynamic Detox Program 10 Day - Chocolate Dynamic Detox Program 10 Day - Vanilla Dynamic Detox Program 28 Day - Chocolate Dynamic Detox Program 28 Day - Vanilla
Liver Support Bundle	Detox Dynamic Detox Program 10 Day - Chocolate Dynamic Detox Program 10 Day - Vanilla Dynamic Detox Program 28 Day - Chocolate Dynamic Detox Program 28 Day - Vanilla
Lysine	L-Lysine
Magnesium Bisglycinate	Magnesium Glycinate
Magnesium CitraMate	Magnesium Citrate
Manganese Bisglycinate	N/A, consider: Mangaplex™
MediBolic	Cardio-Metabolic
MediClear	Detox Dynamic Detox Program 10 Day - Chocolate Dynamic Detox Program 10 Day - Vanilla Dynamic Detox Program 28 Day - Chocolate Dynamic Detox Program 28 Day - Vanilla
MediClear Plus	Detox Dynamic Detox Program 10 Day - Chocolate Dynamic Detox Program 10 Day - Vanilla Dynamic Detox Program 28 Day - Chocolate Dynamic Detox Program 28 Day - Vanilla
MediClear-SGS - Chocolate	Detox Dynamic Detox Program 10 Day - Chocolate Dynamic Detox Program 10 Day - Vanilla Dynamic Detox Program 28 Day - Chocolate Dynamic Detox Program 28 Day - Vanilla
MediClear-SGS - Vanilla	Detox Dynamic Detox Program 10 Day - Chocolate Dynamic Detox Program 10 Day - Vanilla Dynamic Detox Program 28 Day - Chocolate Dynamic Detox Program 28 Day - Vanilla
Melaton-3	Melatonin 20 Melatonin Liquid Melatonin TR Pro
Melaton-5	Melatonin 20 Melatonin Liquid Melatonin TR Pro
Memoractiv	Memories™ with Seanol®-P
Men's Multi 50+	Essential Multi or Essential Multi with Iron
Menopause Bundle	Menopause Support PeriMenopause Support
Meta-Balance	Chasteberry
Metabolic Health	N/A, consider: Cardio-Metabolic
Methyl-Guard	Methyl Complete
Methyl-Guard Plus	Methyl Complete
Methylation Bundle	Methyl Complete
Molybdenum Glycinate	N/A
Multi Enzyme (formerly B.P.P.)	Digestive Complete
Multi-Vitamin Elite	N/A
Multi-Vitamin Elite - NSF Certified for Sport	N/A
Myco-Immune	N/A, consider: Immune Support
NAC - N-Acetylcysteine	N-Acetyl-L-Cysteine NAC-600 Liposomal Glutathione
Niacel® 200	N/A, consider: Cardio Essentials Niacin SR
Niacel® 400	N/A, consider: Cardio Essentials Niacin SR
Niacinamide	Niacinamide 500
Olive Leaf Extract	Oliver
Omega Plus	Omega Pure Complete Omega Pure DHA 600 Omega Pure EPA-DHA 1000 Omega Pure EPA-DHA 2400 Omega Pure EPA-DHA 300 Omega Pure EPA-DHA 500 Omega Pure EPA-DHA 600+ Omega Pure EPA-DHA 720 Omega Pure Kids EPA-DHA Liquid
Omega Superb	Omega Pure Complete Omega Pure DHA 600 Omega Pure EPA-DHA 1000 Omega Pure EPA-DHA 2400 Omega Pure EPA-DHA 300 Omega Pure EPA-DHA 500 Omega Pure EPA-DHA 600+ Omega Pure EPA-DHA 720 Omega Pure Kids EPA-DHA Liquid
Omega-3 with CoQ10	N/A
Ovarian Care	Myo-Inositol Complex
Pantethine	N/A
Perma-Clear	GI Restore
PharmaGABA-100	Pure Gaba GABA-Val®
PharmaGABA-250	Pure Gaba GABA-Val®
Phosphatidylserine (formerly Iso-Phos)	Phosphatidyl Serine
Phosphatidyl Choline	N/A
Phytogen	N/A, consider: Coryza Forte
Phytoprofen	Herbal Eze
Pic-Mins	Essential Minerals
Plantizyme	Digestive Vegetarian
PolyResveratrol-SR	Resveratrol Plus
Potassium Citrate	Potasinase™ Potassium
Prebiotic +	GI Integrity GI Restore
Prenatal DHA	Omega Pure DHA 600
Pro-Resolving Mediators	PRM Resolve
Pyridoxal 5'-Phosphate	N/A, consider: Methyl B12
Quercenase	Quercetin 500 Resveratrol Plus
Quercetin Phytosome	Quercetin 500 Resveratrol Plus
R-Lipoic Acid	R-Lipoic Acid
Recovery Bundle	N/A
RecoveryPro	Performance Drink
Red Yeast Rice + CoQ10 (formerly Choleast)	Cardio Essentials Red Yeast Rice
ResveraCel	Resveratrol Plus
Rhodiola	Stress Essentials Balance Stress Essentials Cortisol Pro
Riboflavin 5'-Phosphate	N/A
S.A.T.	Milk Thistle Complex™
Sacro-B	UltraBiotic Saccharomyces Boulardii
Selenium	Selenase™
Siliphos	Milk Thistle Complex™
Skin Health Bundle	N/A, consider:
Sleep +	GoodNight
Sleep Bundle	N/A
Sleep Bundle for Athletes	N/A
Stress B-Complex	B-Complex
Stress Balance (formerly Phytisone)	Stress Essentials Licorice Complex
Stress Management Bundle	N/A
Super EPA	Omega Pure Complete Omega Pure DHA 600 Omega Pure EPA-DHA 1000 Omega Pure EPA-DHA 2400 Omega Pure EPA-DHA 300 Omega Pure EPA-DHA 500 Omega Pure EPA-DHA 600+ Omega Pure EPA-DHA 720 Omega Pure Kids EPA-DHA Liquid
Super EPA - NSF Certified for Sport	N/A
Super EPA Pro	Omega Pure Complete Omega Pure DHA 600 Omega Pure EPA-DHA 1000 Omega Pure EPA-DHA 2400 Omega Pure EPA-DHA 300 Omega Pure EPA-DHA 500 Omega Pure EPA-DHA 600+ Omega Pure EPA-DHA 720 Omega Pure Kids EPA-DHA Liquid
SynaQuell	Brain Restore Powder
SynaQuell +	Brain Restore Powder
Taurine	Pure Taurine - (capsules) Pure Taurine - (powder)
Theanine	L-Theanine Pro
Thorne Basics Bundle	Everyday Essentials Foundation Everyday Essentials Active Everyday Essentials Men's Everyday Essentials Women's Everyday Essentials Women's Advanced
Thorne x Julianne Hough Bundle	Everyday Essentials Women's Everyday Essentials Women's Advanced
Thyrocsin	Thyro Complex® Thyroid Complex
Thyroid Health Bundle	Thyro Complex® Thyroid Complex
Trace Minerals	Essential Minerals
Training Bundle - Lemon	Performance Drink
Training Bundle - Berry	Performance Drink
Travel Bundle	N/A
Ultimate-E	Annatto Pro 125
Undecylenic Acid (formerly Formula SF722)	N/A
VeganPro Complex® - Chocolate	N/A
VeganPro Complex® - Vanilla	N/A
Vitamin B12	Methyl B12
Vitamin C with Flavonoids (90 count)	Vitamin C 500 Bio Complex
Vitamin D	D3 1000 D3 2000 Iso Complete D3 5000 D3 5000 with K2 D3 Liquid D3 10,000 with K2
Vitamin D + K2 Liquid	D3 Liquid
Vitamin D Liquid	D3 Liquid
Vitamin D Test	Vitamin D - Test
Vitamin D-1,000	D3 1000
Vitamin D-10,000	D3 1000 D3 2000 Iso Complete D3 5000 D3 5000 with K2 D3 Liquid D3 10,000 with K2
Vitamin D-5,000 - NSF Certified for Sport	N/A
Vitamin K - formerly 3-K Complete	Vitamin K2
Vitamin K2	Vitamin K2
Weight Management Bundle	N/A
Whey Protein Isolate - Chocolate	Whey Protein
Whey Protein Isolate - Vanilla	Whey Protein
Women's Multi 50+	Essential Multi
Youth Bundle	N/A
Zinc Bisglycinate 15 mg	Zinc Pro
Zinc Bisglycinate 30 mg	Zinc Pro
Zinc Picolinate 15 mg	Zinc Picolinate
Zinc Picolinate 30 mg - NSF Certified for Sport	N/A
Zinc Picolinate 30mg	Zinc Picolinate

“N/A” means there is no direct NutriDyn replacement listed in this guide. Products marked “consider” are alternatives rather than exact matches.

The Apparent Confusion About Progressive Overload

Apparently, there is a growing disagreement online about progressive overload. Most of it comes from confusing cause and effect, while different people use the same term to mean slightly different things.

Brosef’s explanation from the bench next to you usually goes like this: you get stronger by continually adding more weight to the bar. Since strength and load rise together, it must be the added weight that produced the improvement.

This explanation makes intuitive sense and works reasonably well for beginners, who often improve fast enough to add weight almost every workout. However, it puts the plates before the muscle by mistaking the visible result of progress for the process that made it possible.

The process of building strength starts when you expose the body to a challenging training stimulus. In response, the body may improve neural coordination, become more efficient at the movement, and increase its ability to produce force. Once those adaptations occur, the same weight becomes easier relative to your new capacity. At that point, you can adjust the training demand by adding weight, reps, or changing another variable to keep the stimulus productive.

This creates a repeating cycle:

Training stimulus → Adaptation → Improved performance → Adjusted stimulus

Or, more simply:

You perform a set of five reps → You get stronger → That same set becomes easier → You add some weight to keep it challenging.

Increasing the load can help drive further adaptation, but the increase works best when supported by the capacity you have already developed. When someone forces more weight before their performance has improved, range of motion often shortens, technique breaks down, and control suffers. The number on the bar went up, but the ability being trained likely did not.

Another point of disagreement is how broadly progressive overload should be defined. Some people use it almost exclusively to mean adding weight. Others include more reps, better execution, increased range of motion, or more total work. These can all change the training demand, but they do not demonstrate the same kind of progress.

Adding a rep with the same load, range of motion, and technique provides clear evidence of improved performance. Adding another set increases total training volume, which may be useful for hypertrophy, but it represents a programming adjustment rather than direct evidence that performance on a given exercise has improved. Better execution or greater range of motion may also represent meaningful improvement, although changing the conditions of the movement makes comparison less direct.

Progression works best when it responds to meaningful improvements in capacity rather than forcing the numbers upward at all costs. You apply an appropriate stimulus, recover, monitor performance, and increase the demand when your performance supports the adjustment.

This brings us back to the original confusion between cause and effect. Because the weight on the bar usually increases as you become stronger, it's easy to assume that adding weight is what created the strength. The process works as a cycle: the existing training stimulus produces adaptation, that adaptation improves performance, and improved performance allows you to increase the demand. The heavier load then becomes part of the next stimulus and may contribute to further adaptation.

Progressive overload is therefore the ongoing adjustment of training demands as the body adapts. The controversy becomes much easier to understand once you recognize that progression can be both the result of the adaptation that came before it and part of the stimulus that produces what comes next.

Strength and Training Tolerance Are Different Capacities

The ability to lift a weight and the ability to recover from lifting it are not the same thing.

A workout is usually judged by what someone can complete. If they can move the weight, maintain decent technique, and finish the set, it's assumed the training was appropriate. But completing the work only proves that they were capable of producing enough force in that moment. It doesn’t tell us how much the workout cost them or whether their body can turn that stress into progress.

Two people can perform the same exercise with the same weight and have completely different responses. One may recover quickly and return stronger. The other may experience a large drop in performance, remain sore for several days, and struggle through their next workout. They completed the same task, but the biological cost wasn’t the same.

To understand why, we have to look beyond whether the weight moved and consider what the muscle had to do to move it.

Muscle growth begins when the fibers inside a muscle experience enough mechanical tension to signal that they need to become better prepared for similar demands in the future. Heavy weights can create this tension immediately because the muscle has to produce a lot of force to move them. Lighter weights can also create it, but usually only after fatigue builds and the final repetitions become difficult.

This is why hard sets performed close to failure can stimulate growth. As the set becomes more demanding, the repetitions slow down, the body recruits more muscle fibers, and those fibers are forced to produce more tension.

However, the same set that creates the growth signal also creates fatigue and disruption. The body must restore energy, regulate calcium inside the muscle, repair damaged tissue, and return the muscle to normal before it can fully adapt.

A workout provides the reason to grow, but recovery is where that growth is actually built. The body can increase muscle protein synthesis for two different reasons. It may be using new protein to build the muscle larger, or it may simply be repairing tissue that was damaged during training.

Those processes can happen at the same time, but they don't produce the same outcome.

Imagine you're renovating a house. Some of your budget can be used to add a new room, but if you damage the roof first, much of that money has to be spent repairing what was damaged in the process.

Training works in a similar way. When a workout creates enough tension with manageable damage, more of the recovery process can be directed toward building additional muscle. When it causes excessive damage, the body has to spend more time and resources repairing what was already there.

This is why soreness isn't proof that a workout was productive. A little soreness is normal, especially after unfamiliar exercises, but feeling destroyed doesn't mean the muscle received a better growth stimulus.

The same principle applies to exhaustion. Training close to failure can be useful because the final and most challenging repetitions often create the greatest amount of tension in the muscle fibers. But that doesn't mean every set needs to continue until the weight physically stops moving.

Once the target muscle is working hard and the repetitions have slowed down, much of the useful growth stimulus may already be present. Continuing beyond that point can add more fatigue and muscle damage without adding the same amount of benefit.

The goal is to get close enough to failure that the set becomes challenging, while stopping before the cost begins to rise faster than the reward. For most exercises, leaving 1-3 good reps in reserve is enough to create a strong stimulus while making recovery easier.

This becomes especially important because strength can improve faster than training tolerance.

Someone can become capable of lifting heavier weights before their body is ready to handle much more total training. Their technique improves. Their confidence grows. Their nervous system becomes better at recruiting muscle. These changes can increase performance quickly.

However, the structures and systems that support repeated training may take longer to adapt. Muscles, tendons, connective tissue, energy systems, and recovery capacity all need time to become more tolerant of heavier loads and greater volume.

This creates a common mistake. A lifter adds weight and sets simply because they are capable of completing them. Their strength may be improving, but the amount of stress they can recover from hasn't increased at the same rate.

Good training therefore requires more than asking, “Could I finish the workout?” A better question is, "Could I complete the workout, recover from it, and return ready to perform at a greater capacity next time?"

Signs that the training dose is appropriate include stable or improving strength, manageable soreness, consistent technique, and the ability to repeat the workload without a continued decline in performance. Over time, that same workload should become easier to tolerate, or the lifter should be able to perform slightly more without creating a disproportionate increase in fatigue.

If you can survive the session but spend the rest of the week trying to recover from it, the workout may be creating more disruption than your body can productively adapt to. Being strong enough to complete the work is only part of the equation. Strength is the ability to produce force, while training tolerance is the ability to handle that force repeatedly, recover from the stress it creates, and return better prepared for the next session.

Reimagining the Meaning of Health

When people talk about health, they often assume it's a straightforward and easily definable concept: either you're healthy or you're not. But the moment you try to explain what health actually is, the idea becomes much less clear. Is it how you feel? Is it how your body performs? Or is it something broader that includes how you live, think, and function in the world?

There is a recognized field called the philosophy of medicine, or the philosophy of health and disease, but there isn't one dominant, universally accepted philosophy of health in the same way there are recognizable schools like Stoicism, utilitarianism, existentialism, or pragmatism. The closest thing we have to an official global definition comes from the World Health Organization, which defines health as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.”

The WHO definition falls short as a complete philosophy of health and instead acts more like an ideal. It says health is more than “not being sick,” which is important, but it doesn't fully explain how a person should live, what tradeoffs matter, what the body is for, how much responsibility belongs to the individual versus society, or how to judge health when someone has pain, disability, disease, aging, trauma, or chronic stress.

A better way to frame it is this: there are many different ways to think about health, but no single definition or perspective fully captures what it means in practice.

The main reason is that health sits between biology, morality, culture, medicine, politics, economics, and personal meaning. It isn't purely objective, nor is it purely subjective. A blood marker can be objectively abnormal, but whether someone is healthy cannot always be reduced to that marker. A person can have perfect labs and still be miserable, addicted, socially isolated, weak, anxious, and unable to function. Another person can have a chronic condition but live with strength, purpose, connection, resilience, and high function.

This is why philosophers and physicians distinguish between disease, illness, and sickness. Disease can refer to biological dysfunction, illness to the lived experience of being unwell, and sickness to the social role or recognition of being unwell. Those categories overlap, but they are not identical. Someone can have disease without feeling ill. Someone can feel ill before a diagnosis appears. Someone can be treated socially as sick even when their deeper problem is environmental, psychological, relational, or behavioral.

The major split is usually between two views.

One view is the biological view. In this view, health means normal biological functioning. This is associated with thinkers like Christopher Boorse, who treated health as a theoretical biological concept. The strength of this view is that it keeps health grounded in physiology instead of preference, ideology, or vague wellness language. The weakness is that normal function doesn't fully capture pain, meaning, adaptation, environment, social conditions, or human flourishing. You could describe this view as functional, in the sense that it focuses on whether the system is operating as it is supposed to.

This view becomes more complicated when applied to aging, disability, or chronic conditions. If health is defined only by normal biological functioning, then many predictable features of aging or disability can be treated as straightforward defects. But that misses something important: a person may have limitations, adaptations, or medical realities and still possess a high degree of health in the lived sense if they can function, adapt, participate, and pursue a meaningful life.

The other view is the holistic view. In this view, health is about the person’s ability to live well, pursue meaningful goals, participate in life, and adapt to challenges. This includes thinkers like Georges Canguilhem and Lennart Nordenfelt, and it fits better with real life because health isn't only about whether the organism is working, it's also about whether the person can function in the world they inhabit. A useful parallel term here is integrative or adaptive, since this view looks at how different factors come together and balance to make health possible, rather than focusing only on isolated biological function.

That is why more recent definitions have moved toward health as adaptability. A widely cited proposal in the British Medical Journal defines health as “the ability to adapt and to self-manage” in the face of physical, social, and emotional challenges. That gets closer because health isn't a perfect static state — it's dynamic, requiring the capacity to respond.

So if we had to build a generally recognized philosophy of health from the broad consensus, it would probably be something like this:

Health is the cultivated capacity to function, adapt, and pursue a meaningful life through the integration of body, mind, behavior, environment, and community.

Or put more simply: Health is the capacity to live well in reality.

It's not endless optimization, perfect biomarkers, visible leanness, or total control. It also isn't static or universally experienced in the same way across all people, stages of life, or environments. A real philosophy of health would probably rest on a few core principles that account for both its biological realities and its lived complexity.

First, health is functional. The body should support life, not become the entire purpose of life. Strength, mobility, energy, sleep, digestion, cognition, and emotional regulation matter because they increase someone’s ability to act.

Second, health is adaptive. A healthy person is not someone who never experiences stress, illness, pain, or disorder. A healthy system can respond, recover, reorganize, and continue functioning. This is why the ability to adapt and self-manage is such a useful model.

Third, health is multidimensional. Physical, mental, social, and environmental health cannot be fully separated. The WHO definition gets this part right by refusing to define health as merely the absence of disease.

Fourth, health is both personal and collective. Individuals have responsibility for their habits, but people do not choose all of their conditions. Food access, income, stress exposure, education, neighborhood safety, healthcare access, and culture shape health. One criticism of the self-management model is that it can accidentally blame people who have fewer resources or lower capacity to adapt.

Fifth, health isn't the same as morality. Being healthy doesn't make someone virtuous, and being sick doesn’t make someone a failure. This matters because modern wellness culture often turns health into a moral hierarchy.

Sixth, health exists to support a good and meaningful life. The purpose of health is to expand what life allows: to love, work, think, create, endure, contribute, enjoy, and participate.

Part of what makes a philosophy of health so difficult is that health is too broad to belong to one discipline. Medicine wants diagnosis. Biology wants function. Public health wants population outcomes. Psychology wants resilience and behavior. Philosophy wants meaning and value. Fitness wants performance and body composition. Spiritual traditions often want wholeness, discipline, or harmony.

But the closest modern synthesis would be this:

Health centers on capacity rather than perfection. It reflects a person’s ability to meet life with enough physical function, mental clarity, emotional resilience, social connection, and environmental support to pursue a meaningful existence.

That is the most defensible starting point for a philosophy of health, but it still feels incomplete on its own. A philosophy of health cannot stop at defining what health is in theory; it also has to extend into practice. It needs to account for how health is actually built over time, how it's maintained, how it breaks down, and how it can be restored when it is lost.

Health, to me, isn't just the absence of disease, and it isn't something that can be fully understood through lab numbers, body fat percentage, or appearance alone. It is a state of bodily function, movement quality, emotional steadiness, and physiological resilience that gives a person the freedom, confidence, and capacity to live the life they want.

Someone can look fit and still be unwell. Someone can have impressive numbers and still lack energy, stability, strength, clarity, or peace. Real health is when the body works well, adapts well, and supports a high quality of life without constant limitation, discomfort, or dependency.

This is where my view becomes more specific. I believe health is built by living in alignment with what human beings fundamentally need. That includes movement, sunlight, connection, quality food, sleep, stress management, purpose, time in nature, and daily habits that work with our biology rather than against it.

I don't see the body as a machine that simply needs to be medicated whenever symptoms appear. I see it as a living system that needs to be understood, supported, and respected. Symptoms are not random inconveniences to suppress. They are often signals that something deeper may be out of order. That does not mean medicine has no place. It means medicine should not be the only lens. Real health, in my view, comes from addressing causes rather than only managing consequences.

This also means that health cannot be separated from behavior. The body is shaped by what it repeatedly experiences. The food someone eats, the way they move, the sleep they get, the stress they carry, the relationships they maintain, the light they see, the environments they inhabit, and the standards they live by all become information to the body. Over time, those repeated inputs either support function or erode it.

That is why I do not view health as a temporary intervention or a short-term fix. I see it as a way of living. It is built through sustainable habits, standards, and identity, not through quick fixes or temporary bursts of motivation. A diet only matters if it can actually be lived. A training plan only matters if it can be recovered from and repeated over time. A strategy only matters if it helps someone become the kind of person who can carry it forward.

Therefore, health is not just about what a person does once in a while. It is about what they repeatedly choose, what they value, and who they're becoming.

But health should also lead somewhere. It is not the final goal in itself. It is the foundation that gives a person the ability to act, choose, lead, and live with greater purpose. Good health allows someone to be more present, more capable, and more fully themselves. That is part of why confidence in one’s body matters. It reflects freedom, self-respect, and the ability to move through life with strength and agency.

In this sense, health is both biological and philosophical. It is biological because the body has real needs, real limits, and real consequences when those needs are ignored. But it is philosophical because the point of health is not merely to survive, optimize, or avoid disease. The point is to create the capacity for a fuller life.

Health is not perfection. It isn't a number, a look, a supplement stack, or a temporary state of discipline. Health is the cultivated capacity to live well in reality. It is the condition of the body and mind that allows a person to meet life with strength, adaptability, clarity, and purpose.

And if there is a philosophy of health worth building around, I think it's this:

The body is not the destination. It is the foundation. Health is the practice of building that foundation well enough that life can be lived with more freedom, presence, and meaning.

Why the New Resistance Training Guidelines Feel Both Important and Underwhelming

The American College of Sports Medicine (ACSM) recently released an updated position stand on resistance training for healthy adults. A position stand is essentially an official summary of the current evidence that organizations use to guide recommendations for practitioners, coaches, and the general public. This update revisits and expands on ACSM's 2009 guidance by synthesizing a large body of research on how different training variables affect outcomes like strength, muscle growth, power, and physical function.

When I first saw people discussing the update, I expected the conclusions to feel more surprising. Instead, a lot of them sounded like things many evidence-informed coaches already accept. You do not need to train to failure every set. Muscle can grow across a wide range of loads. Frequency is mostly a way to distribute weekly volume. Machines and free weights can both be useful. Periodization is not automatically superior for every lifter in every situation.

My first reaction was not disagreement as much as confusion. Why was this being treated like big news?

The answer, I think, is that the update is less revolutionary as an advanced coaching document and more important as an institutional correction. It moves resistance-training guidance away from rigid prescriptions and toward a more flexible understanding of what actually drives adaptation.

In other words, the big shift is not that the old methods stopped working. It is that many of the old rules should no longer be treated as universal requirements.

What the Paper Actually Did

The American College of Sports Medicine released an updated position stand on resistance-training prescription for healthy adults. This paper updates their 2009 position by summarizing a large body of research on how different resistance-training variables affect strength, hypertrophy, power, muscular endurance, and physical function.

This was not one new training study. It was an overview of reviews, meaning the authors looked at existing systematic reviews and meta-analyses to determine what the broader literature says about resistance training.

That distinction matters because the paper is not trying to answer the same question a coach might ask when writing a program for an advanced lifter or athlete.

The paper is asking a broad question:

What resistance-training variables consistently improve outcomes across healthy adults?

A coach is often asking a more specific question:

What does this individual need, at this stage of development, with this goal, this recovery capacity, this training history, and this timeline?

Both questions are useful, but they are not the same question. That is part of why the conclusions can feel both important and underwhelming at the same time.

The Big Shift: From Rules to Ranges

Resistance training has traditionally been taught through very specific rules.

Train each muscle two or three times per week. Use a certain repetition range. Rest a certain amount of time. Progressively overload the movement. Periodize the program. Use enough volume. Train through a full range of motion. Choose the right exercises. Follow the right structure.

None of those recommendations are inherently bad. In many cases, they are useful. The problem is that useful recommendations often become universal laws.

The new position stand seems to challenge that way of thinking.

It does not say that programming variables are meaningless. It says that many resistance-training approaches can improve muscle, strength, and function when compared with doing nothing. Once training is hard enough, consistent enough, and organized around the goal, fewer variables appear to have one universally superior setting.

That is the difference between saying:

“This is a useful way to train.”

And saying:

“This is the only correct way to train.”

The first statement may be true. The second is much harder to defend.

Effective Is Not the Same as Optimal

One of the most important distinctions in the paper is the difference between training that is effective and training that is optimal for a specific outcome.

For general health and function, many forms of resistance training work. Free weights, machines, elastic bands, bodyweight exercises, circuit training, home-based training, and other approaches can all produce meaningful improvements if they are performed consistently and with enough effort.

That does not mean every program is equally good for every goal.

If the goal is maximal strength, heavier loading becomes more important because strength is highly specific to producing force against heavy loads. If the goal is hypertrophy, weekly volume and sufficient effort appear more important than forcing one exact repetition range or training frequency. If the goal is power, the program needs to include faster, more explosive intent rather than only slow, grinding repetitions.

This is where the paper can be misread.

It is not saying the details do not matter. It is saying the details matter most when they are attached to a specific outcome.

A beginner trying to become healthier and stronger does not need the same level of programming precision as an advanced lifter trying to peak a competition lift, bring up a weak muscle group, or manage fatigue across a long training cycle.

The Traditional Rules That Became Tools

The most useful way to understand the update is this:

A lot of traditional resistance-training rules should now be viewed as tools.

Frequency is not magic. It is a tool for distributing weekly volume and managing session quality.

Failure is not mandatory. It is a tool for measuring and applying effort.

Tempo is not a secret hypertrophy mechanism. It is a tool for controlling execution, reducing momentum, and keeping tension where you want it.

Exercise selection is not about choosing universally superior movements. It is a tool for directing stress toward the tissues and skills you are trying to improve.

Rest periods are not inherently anabolic or non-anabolic. They are a tool for controlling performance, fatigue, density, and training quality.

Machines and free weights are not moral categories. They are tools that load the body differently and should be chosen based on the goal, the person, and the context.

Periodization is not a magic ingredient. It is a tool for organizing training stress over time.

This does not make the variables unimportant. It makes them conditional.

The question is not, “What is the rule?”

The better question is, “What problem is this variable solving?”

Why the Periodization Finding Feels Strange

The periodization conclusion is probably one of the easiest parts of the paper to misunderstand.

At first glance, it can sound like the authors are saying periodization does not matter. That can feel wrong to anyone who has trained or coached beyond the beginner stage.

But the better interpretation is more specific.

The paper does not show that planning training over time is useless. It shows that formal periodized programs have not consistently outperformed nonperiodized programs for broad strength and hypertrophy outcomes across the available reviews.

That makes more sense when you consider who is often included in resistance-training research.

Many studies involve untrained or minimally trained participants. For those people, almost any sensible resistance-training program can work. A novice can gain strength from improved coordination, better movement skill, increased confidence, and simply being exposed to loading for the first time. Their threshold for adaptation is low.

In that context, a basic program can produce similar short-term progress to a more formally periodized program.

But that does not mean periodization has no value for people with a higher training age or athletic aspirations.

As someone becomes more advanced, the training problem changes. The issue is no longer just getting exposed to resistance training. The issue becomes continuing to create a stimulus while managing fatigue, joint stress, performance demands, skill practice, recovery, and long-term progression.

That is where periodization still matters.

It can help organize volume, intensity, exercise selection, specificity, variation, and recovery across time. It can help an athlete shift from general preparation to more specific performance. It can help someone emphasize hypertrophy in one phase, strength in another, and peaking in another. It can help manage competing qualities that cannot all be maximally trained at once.

So the takeaway should not be:

“You do not need periodization.”

The better takeaway is:

“Not everyone needs formal periodization to make progress, especially beginners. But advanced lifters and athletes often need some form of organized training structure because their problems are more complex.”

Periodization may not be a direct driver of adaptation by itself. It is a way of organizing the variables that drive adaptation.

Why This Feels Underwhelming

If you already follow modern hypertrophy and strength research, a lot of the paper may feel familiar.

It is already fairly well accepted that hypertrophy can occur across a wide range of loads if sets are taken close enough to failure. It is already common to say that failure is not required on every set. It is already known that frequency is often a way to distribute volume rather than an independent growth trigger. It is already accepted by many coaches that machines can be excellent tools, especially for hypertrophy. It is already reasonable to say that beginners do not need complex periodized programs.

So why does the update matter?

It matters because official guidelines tend to lag behind what experienced coaches and researchers are already discussing. The position stand is not necessarily introducing a brand-new way to train. It is updating the official language around training.

That is still important.

Many people still believe resistance training must follow a narrow template to count. They think they need the perfect split, the perfect rep range, the perfect exercise selection, the perfect progression model, or the perfect periodized plan before they can start.

This paper pushes back against that.

For the general population, the most important message is that resistance training is more flexible than many people think. You do not need to train like a bodybuilder, powerlifter, or athlete to receive meaningful benefits. You need a sustainable way to challenge your muscles consistently.

That is not underwhelming for the person who has been intimidated by the weight room for years.

What This Means for Beginners

For beginners, the message is simple.

Start.

Do not wait until you understand every training variable. Do not wait until you know the perfect split. Do not obsess over whether you should use machines or free weights. Do not worry about whether your program is formally periodized.

Train the major muscle groups. Use exercises you can perform safely and consistently. Work hard enough that the sets are challenging. Add weight, repetitions, sets, or control over time when appropriate. Recover well enough to repeat the process.

For a beginner, consistency matters more than complexity.

A simple program done consistently will outperform a sophisticated program that someone cannot understand, recover from, or maintain.

What This Means for More Advanced Lifters

For advanced lifters, the message is different.

This paper should not be used as an excuse to abandon structure. The fact that many variables do not show universal superiority across broad research does not mean they are irrelevant in advanced training.

As training age increases, the margin for progress becomes smaller. The workload required to create adaptation often becomes higher, while the cost of that workload also increases. Fatigue becomes more meaningful. Exercise selection becomes more specific. Recovery becomes more limiting. Weak points become harder to address. Performance goals become more precise.

At that point, programming variables matter because they solve specific problems.

Frequency may be adjusted to distribute volume more effectively.

Exercise selection may be used to bias a lagging muscle or reduce joint stress.

Failure may be used sparingly to increase stimulus without overwhelming recovery.

Volume may be cycled to manage fatigue.

Intensity may be emphasized when strength expression becomes the priority.

Periodization may be used to organize all of those variables across time.

For advanced trainees, the lesson is not that programming matters less. It is that programming should be justified by the goal rather than inherited as dogma.

What This Means for Coaches

For coaches, the update is a reminder to be more precise with language.

There is a difference between saying:

“I like this approach.”

“This approach works well for this person.”

“This is useful for this goal.”

And:

“Everyone needs to train this way.”

A lot of coaching errors come from turning useful tools into universal rules.

A coach should be able to explain why a variable is being used. Why this frequency? Why this exercise? Why this rep range? Why this rest period? Why this phase? Why this progression model?

If the only answer is, “Because that is what a good program is supposed to include,” the reasoning probably needs to be sharpened.

The value of coaching is not just knowing the variables. It is knowing when each variable matters, when it does not, and how to apply it to the person in front of you.

The Real Takeaway

The new ACSM position stand does not mean programming no longer matters.

It means the field is becoming more careful about which programming rules are truly universal and which are context-dependent.

For the general population, the most important message is that resistance training works across a wide range of approaches. You do not need a perfect program to begin. You need a repeatable one.

For beginners, that should be freeing.

For coaches, it should be humbling.

For advanced lifters and athletes, it should not be misread as a dismissal of structure. The more specific the goal and the more trained the person, the more important it becomes to organize training intelligently.

The real update is not that resistance training has changed.

The update is that the rules have become less rigid.

Many of the things we once treated as requirements are better understood as tools. Their value depends on who is training, what they are training for, and what problem the program is trying to solve.

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Reference: American College of Sports Medicine Position Stand. Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults: An Overview of Reviews

The Toxic Burden We Pass Down

Toxic exposure is usually discussed as an individual issue. A person is exposed to a chemical, heavy metal, pollutant, or environmental stressor, and the concern is how that exposure affects their health.

But the deeper concern is that toxic exposure may not stop with the individual.

The amount of a toxin a person is exposed to at any point in their lifetime may influence future generations through epigenetic changes. This does not necessarily refer only to a person’s present toxic load, or total body burden. The concern is that exposure itself may leave biological information that can be passed forward through the epigenetic code.

Epigenetics refers to changes in how genes are expressed. It does not change the underlying DNA sequence, but it can influence which genes are turned on or off, and how strongly those genes behave. In this way, the environment can affect biology in ways that may extend beyond one lifetime.

That means a toxin may not only affect the person directly exposed to it. It may also affect their children, grandchildren, and future descendants.

The concerning part is that future generations may not simply inherit the same level of vulnerability. They may become more sensitive to the same exposure.

For example, scientists have found that when the first generation of frogs is exposed to a given amount of mercury, they display a certain level of injury or mutation. But the damage caused by that same amount of heavy metal doubles in the second generation and doubles again in the third generation, until none of them survive.

Instead of gaining tolerance, which can happen in some biological processes, they developed a dramatically greater intolerance with each generation.

That matters because it challenges the way we usually think about adaptation. We often assume that repeated exposure might make an organism stronger or more capable of handling the stressor. But with certain toxins, the opposite may happen. The exposure may alter gene expression in a way that increases vulnerability rather than resilience.

This is the idea of generational body burden.

A toxic exposure may affect the parent, but it may also change how future generations respond to environmental threats. The same amount of toxin may cause more harm later because the inherited epigenetic pattern has made the organism less capable of tolerating it.

That increased sensitivity can make future generations weaker in several ways. They may have a harder time fighting off environmental threats. They may struggle more to recover from health challenges. They may also have a reduced ability to normalize or compensate for genetic defects.

This does not mean every exposure automatically creates permanent damage in every descendant. It does mean that toxic exposure should be taken more seriously than a single-lifetime model allows.

The body is not isolated from ancestry. Health is shaped by the environments we live in, but also by the biological history passed down to us. The exposures of previous generations may influence how resilient or vulnerable the next generation becomes.

This also means that reducing toxic exposure matters beyond personal health. The choices we make around food, water, chemicals, heavy metals, air quality, personal care products, and environmental burden may influence more than our own biology.

They may shape the biological starting point of the people who come after us.

That is why detoxification and toxic load should not be treated as trendy wellness language. The body carries information from its environment. Some of that information may be passed forward. If toxic exposure can influence gene expression across generations, then lowering exposure becomes part of a larger responsibility.

We are not only managing our own body burden.

We may also be influencing the burden inherited by future generations.

What You Put on Your Skin Still Enters Your Body

Most people pay attention to what they eat, drink, and breathe, but they often forget that the skin is also an entry point into the body.

When you put chemicals, makeup, skincare products, oils, soaps, hair products, or other substances on your skin, some of those compounds can be absorbed through the skin and enter circulation. This is one reason personal care products deserve more attention than they usually get.

A simple example often used to explain this is a garlic poultice. A poultice is a soft, moist mass of some substance applied to the body for a medicinal purpose and kept in place with a wrap of cloth or plastic. If garlic is applied to a baby’s feet as a poultice, it has been said that the smell can appear on the breath shortly after. Whether or not that example is precise in every case, the larger point is that substances placed on the skin can influence the body beyond the surface.

Medical science already understands this principle. Transdermal medications have been used for decades. Medicinal patches are applied to the skin when oral delivery is not ideal, when absorption through the digestive tract is poor, or when a steady delivery of medication is preferred.

That alone should change the way we think about skincare and personal care products.

The skin is not an impenetrable wall. It is a living, responsive barrier. It protects the body, but it can also absorb certain substances. The degree of absorption depends on the compound, the condition of the skin, the area of application, the amount used, and how often it is applied.

What makes skin absorption especially important is that substances absorbed through the skin do not go through the liver first in the same way swallowed substances do. When you eat or drink something, it generally passes through the digestive system and then through the liver before reaching the wider bloodstream. This is part of what is called first-pass metabolism.

When something is absorbed through the skin, it can enter circulation more directly, do what it is going to do, and then be filtered by the liver later.

That matters because personal care products are not occasional exposures for most people. They are daily exposures. Makeup, lotions, sunscreen, deodorant, shampoo, conditioner, soap, fragrance, shaving products, and skincare formulas can create repeated contact with chemical compounds over time.

The concern is not that every product is automatically dangerous. The concern is that most people use these products casually without thinking of them as part of their total toxic load.

If something is applied to the skin once, the exposure may be small. But if multiple products are used every day for years, the cumulative exposure becomes more relevant. The body has to process what it absorbs.

This is why personal care products should be treated with the same level of awareness as food. The skin may be external, but what you place on it does not necessarily stay external.

A better approach is to simplify where possible. Use fewer products. Choose cleaner formulas when you can. Avoid unnecessary fragrance. Pay attention to ingredients. Remember that the body is exposed not only through food and air, but also through the products used on the skin every day.

Your skin protects you, but it also connects you to the environment.

That means what you put on your body still matters to what happens inside your body.

Why High-Glycemic Post-Workout Meals May Work Against Muscle Growth

Glycemic load is a term used to describe the effect a food has on blood sugar. The higher the glycemic load, the more that food raises blood sugar and insulin.

Over the years, there has been growing public awareness around glycemic load and how it affects health. More people understand that certain foods spike blood sugar more aggressively than others, and that repeated blood sugar and insulin spikes can affect metabolism over time.

However, this topic is still widely misunderstood, especially in sports nutrition.

One of the most common assumptions is that high-glycemic protein meals promote muscle gain. Many commercial protein products are packed with sugar and marketed around the idea that deliberately spiking insulin after training will help drive more nutrients into muscle and produce better growth.

The logic sounds simple. Insulin is an anabolic hormone, so if you spike insulin after training, it should increase protein deposition in the muscle and improve muscle gain.

That is the idea.

But that is not necessarily what happens in real life.

In real life, high-glycemic protein meals may be counterproductive for muscle. There are two main reasons why.

First, exercise causes a temporary disruption in glucose utilization in the muscle. This is related to muscle microtrauma, or the wear and tear that occurs in muscle tissue during training. Immediately after exercise, the muscle may not tolerate a high-glycemic meal as well as people assume.

The post-workout window is often described as a time when the body can handle anything because the muscles are “primed” for nutrients. But that idea may be too simplistic. Training creates demand, but it also creates stress. The body still needs to manage inflammation, tissue damage, glucose handling, and recovery.

Second, high-glycemic meals can impair insulin function, disrupt muscle mTOR signaling, and interfere with muscle protein synthesis. mTOR is one of the key biological mechanisms involved in building muscle. If insulin sensitivity is impaired, mTOR cannot be fully activated in the way people want.

This is where the insulin-spike theory starts to fall apart.

Insulin matters, but more insulin is not always better. The goal should not be to constantly force the largest possible insulin response. The goal should be to maintain insulin sensitivity so the body can respond properly to the insulin it produces.

There is a major difference between using insulin effectively and chronically overspiking it.

Chronic intake of high-glycemic meals has been shown to cause hyperinsulinemia, a condition where insulin is repeatedly or chronically elevated. Hyperinsulinemia has been linked to uncontrollable fat gain, damage to insulin receptors, and harm to the muscular system.

That matters because muscle growth does not happen in isolation. It depends on the health of the entire metabolic system. If the diet repeatedly drives excessive insulin responses and worsens insulin sensitivity, the body may become less efficient at using nutrients properly.

In that environment, the same meal that was supposed to help build muscle may contribute to fat gain and metabolic dysfunction instead.

This does not mean carbohydrates are bad. It does not mean insulin is bad. It does not mean post-workout nutrition does not matter. The issue is the assumption that a high-sugar, high-glycemic protein meal is automatically the best way to support muscle growth.

Muscle growth requires training stimulus, adequate protein, enough total calories, recovery, and proper nutrient timing. But none of that requires turning every post-workout meal into a blood sugar spike.

A better approach is to support recovery without overwhelming the body. That means prioritizing high-quality protein, choosing carbohydrates based on the person’s training, goals, and insulin sensitivity, and avoiding the belief that more sugar automatically means more muscle.

The body builds muscle through coordinated signaling, not through brute-force insulin spikes.

High-glycemic post-workout meals may sound effective because they appear to match a simple anabolic story: spike insulin, drive nutrients, build muscle. But the body is more complex than that. If insulin sensitivity is impaired, glucose handling is disrupted, and mTOR signaling is compromised, the strategy can work against the very outcome it is supposed to support.

The goal after training is not simply to raise insulin as high as possible.

The goal is to create the internal conditions that allow the body to recover, repair, and build muscle efficiently.