3 Muscle Growth Myths Debunked

Chapters:

00:00 1. Deloads for anabolic resensitization

03:58 2. Anabolic resource competition

07:25 3. Only the last 5 reps to failure count for growth

11:15 Outro

Transcript:

An argument for delaod weeks and other forms of volume cycling is that they may cause anabolic resensitization. The idea is that during the course of a training program you desensitize to the anabolic stimulus from the training and fatigue accumulates. As you do a deload week, you get rid of the fatigue and you resensitize the anabolic tissue, and afterwards you’ll actually grow muscle faster. So can you get more gains with less work? A new dissertation study put this to the test.

I would note that because it’s a dissertation, it has only been peer reviewed by the university and not by an academic journal, but the researcher in question is quite capable. I know him personally, so I don’t expect massive changes during peer review. In this study, 37 trained men and women trained one of their calves with a constant training volume -12 sets to failure for 20 weeks straight. The other group had two four week periods of extended deloads or volume cycling, if you will, where they did only four sets, basically minimum effective volume, to failure during those periods and during the rest of the periods they were still training with the same volume as the constant training volume group.

Muscle size was measured via ultrasound muscle thickness measurements with an added check with a simple tape, checking the circumference of the muscle. The volume cycling did not result in anabolic resensitization. Muscle growth rates, after the extended deload periods, were the same as before. Consequently, the constant volume group ended up with slightly better gains. The effect sizes were small, but it was a 99% Bayesian probability of superiority for muscle growth and 82% for 10 rep max strength gains. There was even some evidence that during the lower volume phases the calves shrink a little bit. These were trained individuals, so four sets a week did not seem enough to make gains, or even consistently maintain their gains. Other research has generally found that four sets a week is definitely enough to maintain your gains if you train hard enough.

An arguably large limitation of the study is that 12 sets a week, even if done to failure, is probably not enough for many people to warrant a deload week, especially not a four week deload week. However, if we look at previous research, we have seen that deload weeks have similar effect, even in trained individuals doing 20 sets a week to failure for their calves and their quads. In this study, taking a week off every four weeks reduced strength gains with 85 to 92%. Bayesian probability and muscle growth was largely unaffected, but the effect sizes, 8 out of 10 of them, also favored not deloading.

Taken together, these studies can be understood with a very simple explanation. In my experience many lifters tend to seek for very elaborate, complex explanations that seem intelligent, but scientists actually often prefer the simplest explanation. This principle is called Occam’s razor. The simplest explanation is often statistically, simply the most likely. In this case, the simplest explanation is that doing a deload week has nothing to do with volume cycling, or the deload week per se, is just a reduction in the average training volume. Whether you achieve that with slightly lower volume during the whole period, of one week without any training probably doesn’t matter as much. In that sense, the new study was simply a comparison of an average of 12 sets per week versus an average of 8.8 sets a week. This is consistent with the literature that, on average, people make better gains with 12 than with around 9 sets. However, the difference is not very big because it’s a relatively small difference in training volume.

As for deloading for recovery, my strong preference, what I teach my students in my PT course and what I also implement in my app is reactive loading. Proactive deloading doesn’t make a lot of sense because you don’t know when you will need it, and you also don’t know which body parts need it. So a reactive deload scheduled for muscle groups when they regress in performance, or when you plateau in performance, and then you specifically deload that body part when your data tell you that this body part has probably not yet recovered from the previous workout. This means that you specifically deload the body parts that actually need it when they actually need it.

The second new study I have for you today looked at another relatively complex idea in bodybuilding -anabolic research competition. Some bodybuilders claim that if you do a lot of volume for one body part, then you cannot get the maximum gains with another body part because you have a limited pool of anabolic resources and muscles compete for that pool. This would be an argument, for example, for specialization phases, as opposed to just doing the same volume for all muscle groups. A new study put this to the test. The researchers had 105 untrained individuals either stay untrained, the control group, or introduce them to the wonders of biceps training, and they trained their biceps either just training their biceps or they trained their biceps, and afterwards they trained their quads. Specifically, they did bicep curls and leg extensions.

After six weeks, the gains in their one rep max and muscle thickness were virtually identical between the groups, so it didn’t matter whether they trained their legs after their arms, the gains and their arms were the same. The researchers titled their paper: “Skeletal muscles do not compete for growth: Activating additional muscle mass does not compromise changes in muscle size.” This might seem a bit like an overreach, given that this was a six week study and in untraind trained individuals doing only six sets of biceps girls and then 12 sets of quads, and yes, it was to failure, but that’s still a very, very low training volume, in a short duration, in untrained individuals.

However, the idea is probably true because this study builds on a large literature that already exists with much higher training volumes, which actually found some trends for leg training to increase gains in bicep size. This was the whole idea of training legs, especially with compound movements like squats, to get a positive anabolic hormonal milieu to stimulate arm gains. Most of these studies have failed to replicate, but it’s quite clear that doing even significant leg training after or before arm training does not compromise gains in your arms. If anything, it’s the case that leg training might be slightly positive for your arms.

Mechanistically this makes perfect sense because research is very clear that muscle growth is primarily a local process. Your biceps is a slab of meat. You put tension on it, the meat grows. That’s muscle growth. There aren’t a lot of whole complicated systemic effects, fatigue, many of these things that you hear are simply bro science. Again, Occam’s razor. The simplest explanation is often the best.

So what I teach the students in my PT certification and what I implement in my app, is that program design should basically be a combination of individual programs for every single muscle group. You can emphasize a muscle group by doing more volume for that muscle group and putting it earlier in your workouts, but by and large, what you do for your triceps does not affect how your hamstrings grow. The only thing that affects how your hamstrings are growing is how you train your hamstrings.

So an optimized total training program is basically the sum of an optimized program for each individual muscle group, then put together in a way so that the optimal volumes actually work out. Which, of course, is where science meets art, because if you’re doing squats, you’re not just training your quads, you’re also training your glutes, which means that you have to make all of the muscle groups fit together. The volumes have to work out. This is a large part of optimized program design, and it can be complex, so if you want an app to do it for you, you can check out my app in the link in the description. You get the two week free trial, and it optimizes your volume for every single muscle group. And you can also select which one of those you want to emphasize or not.

The third new study I have for you today looks at another complex idea of how to gain muscle. The idea is that only the last five reps of a set, the last five reps to failure, are effective reps for muscle growth. Everything you do before that is basically wasted effort. It’s just there to get you to the point where muscle recruitment is high enough to actually stimulate significant muscle growth. This means that if a set is not within five reps to failure, it shouldn’t really result in muscle growth and every set can contribute at a maximum five effective reps. A new study put this to the test.

19 strength trained men and women trained one of their legs to absolute brutal failure with leg extensions, true momentary muscle failure under supervision. The other group left two reps in reserve. Training intensities as percentage of one rep max were equated, and they did no other quad training. After eight weeks muscle growth was very similar between the groups, with no clear trend in the data for any group to outperform the other group. There were 3-4% increases in muscle thickness with ultrasound scans across the vastus lateralis and the rectus femoris. Gains in one rep max strength were also virtually identical.

However, I would note that strength gains in this case are confounded because you’re training both of your legs and there is a cross education effect. When you train one leg, the other leg also gets stronger. Basically, the motor cortex, the part of your nervous system that governs movement, learns that if you train your right leg, it’s like, hey, I can do this trick with the left leg as well. And therefore your recruitment and the coordination of the left leg also improve. Motor cortex is just mirroring what it learned on one side and applying it to the other side. Now, importantly, many people think that this confounds muscle growth, but it does not. It’s purely a neural learning effect. Going back to the earlier study, what happens in one leg in terms of muscle growth does not affect the other leg. It’s just a slab of meat. Whether it’s exposed to tension or not is the only thing that determines whether it grows.

These results are hard to reconcile with the idea that only the last five reps to failure are effective, because one group clearly should have just had two more effective reps in every set, in this case. However, most research has found that it’s not just the last five reps that stimulate muscle growth. Every rep stimulates tension on the muscle. Every rep is therefore effective to at least some degree, and what ultimately determines the total growth stimulus is primarily the total repetition volume. I’ve covered training to failure multiple times on this topic, and the conclusion every single time is that the total volume of repetitions is what determines whether you grow or not, and how much you grow. So whether you hit failure or not by itself doesn’t really matter.

Now, what often happens in these studies is that when you train to absolute failure, your reps drop so fast that the group leaving some reps in reserve actually ends up with the same total repetition volume. If you end up with the same total repetition volume, in research you get the same gains.

For example, multiple prior studies have compared to doing a 4 sets of 7 at 12 rep max versus 3 sets to failure, which tend to end up with the same repetition volume, and therefore they also end up with similar muscle growth. Both of these options end up with more muscle growth than 3 sets of 7. So when you do 3 sets of 7 you can increase your repetition volume by doing an additional set of 7, or you can increase your repetition volume by training harder and doing your sets to failure. In both of these cases, you increase your total repetition volume and it doesn’t seem to matter how you achieve it. The results in muscle growth are the same.

Unfortunately, a massive gap of the new studies that they didn’t actually measure the total repetitions, but because they were doing 5 to 6 sets to absolute failure under supervision, I think it’s very likely that they lost reps significantly faster than the group leaving two reps in reserve. And like I said, in previous research we see that you often end up with a similar total volume and therefore similar total gains. The conclusion from this study is therefore not that you can just train less hard and still make better gains. Training harder does improve muscle growth because it increases your total training volume, specifically your repetition volume. But actually hitting failure is not necessary for muscle growth.

I hope these new studies help you stop overcomplicating training program design. If you’re interested in more detailed, comprehensive coverage of how to gain muscle and how to take your physique to the next level, check out my online PT course. The link is in the description. Or if you just want to apply everything for yourself, you can also get a two week free trial to my app, which will do everything for you. See you next time!