Manipulating Training Variables (Part I) – On the Confusion Surrounding Muscle Confusion

In a hurry? Have some highlights. (TL;DR)

  • If you constantly switch exercises, it is quite possible to make some progress on an each exercise without really making significant long term changes to your strength and physique.
  • This is in part made possible by immediate improvements in coordination and other neural adaptations that allow individuals to get more out of the muscle they already have (within a specific context).
  • A lot of programs make use of this phenomenon to allow trainees to feel like they are progressing while they are really just consecutively making small steps in different directions.
  • While strategically altering your training parameters to take advantage of these adaptations is a good way to keep progressing, aimlessly switching exercises for the sake of “muscle confusion” will probably lead to nothing but stagnation.

What’s the deal with muscle confusion?

If you’ve ventured near the vicinity of any kind of fitness-related site, magazine, etc. within the past decade, you’ve probably heard about the concept of muscle confusion. At it’s fundamental, untainted core, the idea of muscle confusion has merit… sort of (even though the name is kind of silly). Let me clarify. Assuming nutrition and rest are adequate, our bodies adapt to stressors like resistance training in multiple ways to prepare should that stress occur again. While the concept originated from studying immune responses to foreign tissues in mice, you’ll hear people refer to these adaptations a lot in the framework of general adaptation syndrome, or the process by which the body acutely responds to a stressor with an adaptation that will lend the body resistance to that stress for some amount of time following its onset. In gym speak, this basically means that once we do some amount of work (training), our bodies will make adaptations through mechanisms like building muscle or otherwise increasing our ability to generate force. If we continue to just repeat that same amount of work over and over, our bodies will not be inclined to adapt further beyond these original adaptations. So what are we to do to keep the gains a-flowin’? We change the stimulus. This is where the idea of muscle confusion is born.

Now, let me set things straight right out of the gates: I’m not advocating what a lot of cheesy programs are selling to people as muscle confusion. You’ll probably recognize catch phrases like, “Using the advanced, scientific principle of muscle confusion, XYZ program switches exercises—EVERY. FREAKING. DAY.—to keep you on your toes and get you lean and shredded while preventing those pesky plateaus!”

Let’s address this like reasonable people. Switching up what movements you are “training” every time you walk into the gym or even every couple of weeks is kind of analogous to trying to walk from point A to point B while totally randomizing the direction you’re travelling with each step. You’re going to end up somewhere, but it’s probably not going to be at point B, and it also isn’t incredibly likely to even be too far from where you started. I put the word training in parentheses because training implies that you are following a specific plan to hone a particular skill for some purpose. In the case of a strength athlete, training means following a (hopefully) logical progression that will increase both their overall strength and their ability to demonstrate that strength in their particular event (e.g. a powerlifting competition). When it comes to the average gym-goer who just wants to feel good, look good, and be generally physically capable, there is more wiggle room for exercise selection because they are not training to compete in specific events, but they will probably still be best served to pick a variety of movements—say, for example, variations of a squat, a deadlift, and presses and pulls in the vertical and horizontal directions—and train them progressively for long periods of time, allowing them to develop an appreciable amount of strength and skill in the movements and, of course, to reap the favorable body adaptations that accompany this process.

Blood flow restriction training—confusing to the muscle, or just the other people in the gym?!

But what about those pesky plateaus?

Ah, yes. Those pesky plateaus. Let’s look at America’s favorite exercise, the barbell bench press, as an example. Yes, if you start off doing something like 5 sets of 5 on the bench and just keep trying to increase weight indefinitely without changing anything else, you’re probably going to hit a wall (AKA a plateau) at some point (after you’ve made some great gains, mind you) with both your strength and muscular development. So what do you do once you hit this plateau? I think everyone will agree that switching things up intuitively sounds like a good idea. The real question is how do we switch it up?

This is right around where a lot of people talking about muscle confusion go over the deep end. A lot of programs and advice out there recommend that you totally switch the exercises you’re using every 2-4 -ish weeks with the hypothesis being that this will prevent you from reaching a plateau (hell, some programs have you never doing the same exercise even twice consecutively), but how does this work in practice? Looking back to the barbell bench press, sure, you can switch the focus to working your incline dumbbell press for three weeks, and then your decline barbell press for three weeks, and then your loaded dips for three weeks, and in each three week block, you will probably make some progress. It might seem great, consistently making progress after stalling out on the boring old  5×5 bench press, but wait… We have to ask ourselves: what exactly are we making progress on? Go back and check your bench press strength after all of this and you’ll probably find it didn’t really move too much. But you were making gains that whole time! What gives?!

Well, while there are probably multiple contributing factors, the research would indicate that a lot of the progress you were making on each individual exercise was largely due to what would nowadays probably be called a hack by many, only in this case, the “hack” was not well implemented to move you towards the goal of increasing your bench press numbers. What is this “hack” I speak of? Neural adaptation.

Specifically, I’m referring to the neural adaptations that occur in response to weight training which allow you to essentially activate your muscles with more intensity than you would have previously been capable of. Normally, untrained individuals have a multitude of spinal reflexes and other mechanisms that act as sort of “governors” of muscle activation and are most often presumed to be largely for the purpose of preventing self-injury from excessively forceful muscle contractions (in other words, the force we can produce from maximal voluntary contractions is lower than the absolute force maximum that amount of muscle would theoretically be able to produce during a full contraction). One example of this is the inverse myotatic reflex, in which something called a Golgi tendon organ can actually start to inhibit a working muscle as it detects increasing tension in the muscle tendon. You can probably see why this would be desirable for preventing injury, but these mechanisms also decrease our potential to exhibit strength with a given amount of muscle tissue. Luckily, it appears that strength training can actually modulate these systems to allow us to increase our maximal voluntary contraction force closer to the theoretical limit. Voila! You’ve gotten stronger without really building any muscle.

Another very important and often overlooked factor to consider in these neural adaptations is the development of coordinated motor patterns. For one thing, it takes time to find your groove and get comfortable/confident with a movement (even psychologically), but there’s more to it than that. While most of us probably never stop to consider it, it takes some pretty impressive spatial awareness, coordination, and timing to activate all of the proper muscles in the proper order to execute a movement like a dumbbell press (and that seems trivial compared to how complicated an action as seemingly simple as walking is to carry out mechanically). Luckily, our brains have a lot of the details ironed out enough that we can think in macroscopic commands like, “PRESS!” instead of thinking, “Increase pec activation; inhibit lats; adjust; activate rotators; adjust; activate forearm flexors; activate forearm extensors; increase triceps activation; inhibit biceps; adjust; increase rotator activation; adjust; adjust; adjust.” This is still a gross oversimplification, but the point is this: aside from the immediate improvements trainees will see from simply practicing a skill (e.g. a new exercise), it has been shown that strength training also leads to improvements in coordination when it comes to things like appropriately activating and inactivating synergistic and antagonistic muscle groups (in most cases, more timely activation of the former and inhibition of the latter) that further increase the amount of strength that trainees can exhibit in the practiced movement.

There are decades of research that have tried to query the exact mechanisms by which these neural adaptations form. Early on, many studies focused on electromyographic (EMG; recording muscle activity with electrodes applied to the skin) recordings to try to deduce how the underlying activation of individual motor units within a muscle changed in response to weight training. More recently, the focus has shifted to techniques like electroencephalography (EEG; recording cortical activity with electrodes applied to the scalp) and transcranial magnetic stimulation (TMS; inducing cortical activity by magnetically stimulating at the level of the scalp) to respectively probe and influence cortical activity before and after resistance training. While there have been many interesting individual findings, we have yet to pull everything together into a full, cohesive explanation of neural adaptations to strength training. Suffice to say, it appears to be a complicated, multifaceted process that can take shape in different ways depending on the individual and the way that they train.

Wait a Second…

So why do we care about any of this? Let’s get back to the scenario of rotating our pressing exercises every three weeks. As we just discussed above, it is quite possible to make increases in strength on a movement with neural adaptations in the absence of significant changes (e.g. hypertrophy) in the involved musculature. The aforementioned studies have shown that the discrepancy between strength development and hypertrophy is especially evident early on in new lifters as they begin resistance training. Looking at the graph above, we can see a qualitative, simplified illustration of this phenomenon (the take-away again is that you can get a boost in strength on a particular movement in the first few weeks of training it without necessarily making many changes to your musculature). In fact, many studies have indicated that neural adaptations are the predominant drivers of strength improvements for around 3-5 weeks when a new movement is being trained.

Hey, wait… 3 weeks. That’s how frequently those magazines told us to switch things up! So it seems likely that at least part of the progress we’ve seen in each 3 week cycle has occurred courtesy of neural adaptations. But is this generally a good thing or a bad thing? Have they pulled the wool over our eyes, or is this the smart path to strength? The answer—as it so often seems to be—is that it depends (although if we’re talking about the typical cookie cutter magazine program, then yes, they’ve probably pulled the wool straight over on us). In short, it turns out switching exercises every three weeks is a good way to keep progressing… on different exercises. Now, I’m not saying that following this kind of routine is not going to lead to some amount of net gain in terms of both muscle growth and strength development, as plenty of people do find varying amounts of success with such tactics, depending on how they choose to execute the rotation and, probably more importantly, how hard they are working—let us never discount the value of hard work. There are always going to be examples of people that have achieved good results without paying too much attention to the details of what they are doing in their training just because they are working their asses off. I’m just pointing out that frequent exercise hopping is not optimal for building towards a goal, unless your goal happens to be getting really good at exercise hopping.

Before I wrap this up, lest any fans of the conjugate method become enraged, I’ll point out a few important considerations, not the least of which being that I do not disagree with the ideas behind the system. The conjugate method is a training system/philosophy popularized by Louie Simmons and his Westside Barbell crews that utilizes regular rotation of movements that are similar to—or conjugates of—the big three powerlifting competition movements for “maximal effort” strength work, usually two days per week (upper and lower). Many people who train this way also have two days per week dedicated to “dynamic effort” (basically speed/technique) work on the competition lifts as well as repetition work. There are a lot of tremendously strong individuals that this way, and it clearly works. When it comes to newer lifters looking to hop straight into something like this, though, I just have a few things to point out about the people that tend to derive the most success from the conjugate method:

1) These guys are well advanced (at least a decade or two) into their lifting careers, and they have already built a huge foundation of muscle, to the extent where getting stronger is largely going to be an issue of improving neural efficiency and perfecting technique, which brings me to 2) These lifters continue to do weekly work (even if it is lighter dynamic effort, or submaximal work like I talked about here) on their competition movements even when they are dedicating their maximal effort days to more general variations of these movements (i.e. the never really stop practicing their competition movements), and lastly 3) These lifters usually still use a lot of repetition work to stimulate hypertrophy in “weak” links following their rotating maximal effort movements. It also shouldn’t be overlooked that this is all done under the watch of expert, knowledgeable eyes that can guide the lifters towards movements that will truly strengthen them where they have weaknesses.

I tried training with a conjugate system by myself a couple of years ago and didn’t have great results, which was probably a combination of my not being ready for it mentally or physically as well as my lack of a deep understanding of the things that were holding my lifts back (my weak points). Were I to give it another try now, I think that I would probably be able to gain more out of it. In short, I’m not at all saying that rotating strength movements regularly can’t work, I’m just saying that unless you are quite advanced and really know the ins and outs of what you are doing and why you are doing it, it is probably not going to be the optimal strategy for you.

What’s the alternative?

Does all of this mean that we should avoid switching things up completely? Definitely not. The point that I have been building towards with all of this is simply that there are ways to switch up your training parameters that will be much more conducive to pursuing your strength and physique goals than just hopping over to a new exercise every time you start struggling or feeling bored. What ways, you ask? Well, the short answer is by altering our training stimuli in ways that don’t diverge drastically from our goals. If you want to know more, stay tuned (sign up for the newsletter for weekly updates!) for part two of what I’m planning to be at least a three part discussion on training variables, specificity, and the periodization of training.

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Let me know in the comments below (you should be able to just comment through Facebook, etc. without logging in now!) if you’ve ever struggled with plateaus or spinning your wheels in the gym because of a general lack of direction!



  1. Carroll, T.J., S. Riek, and R.G. Carson, Neural Adaptations to Resistance Training: Implications for Movement Control. Sports Medicine, 2001. 31(12): p. 829-840.
  2. Sale, D.G., Neural adaptation to resistance training. Medicine & Science in Sports & Exercise, 1988(20): p. S135-45.
  3. Carroll, T.J., et al., Neural adaptations to strength training: Moving beyond transcranial magnetic stimulation and reflex studies. Acta Physiologica, 2011. 202(2): p. 119-140.
  4. Moritani, T., Neural factors versus hypertrophy in the time course of muscle strength gain. American Journal of Physical Medicine & Rehabilitation, 1979. 58(3): p. 115-130.


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