The fastest way to build muscle: 2 new studies [2025]

Chapters:

00:00 Intro

00:16 Training to failure study

04:57 Training volume study

05:07 My Online PT Course

05:31 Training volume study (continued)

09:26 Conclusion

09:54 Outro

Transcript:

What is the fastest way to build muscle? Is it to do a few sets very hard like high intensity training, Dorian Yates style? Or is it more effective to leave some gas in the tank but do a lot of volume to compensate, like modern bodybuilders? Two new studies provide us with answers.

The first study looked at training proximity to failure. How close to failure we should train? The researchers divided a group of strength trained individuals into two groups. One group left only one rep in reserve during their entire training program, training very close to failure. The other group left 1 to 4 repetitions in reserve going from 4-3-2-1 on a weekly basis, rotating through that twice. Other than how close to failure they trained, both groups otherwise followed the same identical upper-lower training split. The subjects included men and women, and all of them were strength trained. After ten weeks there were no significant differences between the groups in either strength development, measured as bench press and squat 1RM strength, or muscle growth, measured as triceps and quadriceps ultrasound muscle thickness.

One wishful interpretation of these results that I’ve seen floating around online is that it doesn’t matter how hard you train. “Sure! Leave some reps in reserve, you’re going to get the same results anyway.” Unfortunately, this is not the case based on the totality of evidence. Multiple meta-analysis of a far larger number of studies have concluded that training to failure does increase muscle growth if, and only if it increases total repetition volume. So if you have two groups of individuals and one of those groups simply does 2 extra repetitions in every set, thereby simply doing a higher total training volume, they will grow more muscle. However, if the training volume does not significantly differ between the groups, you typically don’t see significant differences in muscle growth or strength development between the groups either. And in the current study total training volume, defined as sets x reps x weight, did not significantly differ between the groups.

This is probably in large part because ten weeks is still a pretty short period of time for train lifters to gain a substantial amount of muscle mass and the difference in training proximity to failure was on average only 1.5 repetitions. This is within the margin of error of most people’s ability to actually estimate how close to failure they are. So it’s very likely that this study was simply statistically underpowered to detect a very small expected difference in muscle growth in favor of the group training harder.

However, another consideration with training to failure is that the total training volume is what matters the most. If you go to failure or very close to failure on your first sets, this can reduce the number of repetitions you do in the later sets, thereby not actually increasing your total training volume compared to training a little bit further away from failure which would allow you to do more repetitions in the later sets. In this scenario you can also get equivalent results. For strength development the literature overall is quite clear that training to failure does not make a big difference.

For strength development muscle activity, rate of force development and power output are much more important to learn good technique and maximize total power output. And you don’t have to go to failure to stimulate good strength development. So my conclusion from this study is not that training for failure does not matter, but that there are multiple ways to Rome. You can either do fewer harder sets or more lighter sets, and you can stay a little bit further away from failure, but doing more volume in your later sets, or you can already gas yourself out earlier in your first sets and accept a bigger drop off in repetitions. And all of these methods can lead to similar results, as long as you get in a good total amount of training volume, and your total training stress is adequate.

In practice, though, there is a huge caveat. I don’t recommend training very far away from failure because most people underestimate how far away from failure they truly are. Even powerlifters and very serious competitive lifters can do one more repetition than they thought they could if really pushed. Typically, as you get further away from failure, and as you look at less motivated individuals, the gap between how many reps they still think they could do and how many reps they actually could still do increases. This means that if you think you’re 3 to 5 repetitions away from failure, you might actually be some 10 repetitions away from failure, and then you can do all the sets you want, but you’re probably not going to build a whole lot of muscle staying 10 reps away from failure.

Since people are imperfect at estimating how close to failure they are, I think a good argument can also be made to just do as many reps as possible on every set. This method is simple and effective. One last tidbit about this study is that the lifters got better at estimating how close to failure they are over the course of the study. Now, you might say: “Duh, Menno! Obvious!”, but actually most studies have not found that people get better at estimating how close to failure they are, and trained lifters are no more accurate than untrained lifters of similar motivational level. The reason for this is that just doing something does not necessarily make you better at it. You need feedback.

In the present study the lifters varies their proximity to failure, so they got feedback on how good they were at estimating how close to failure they were. Many lifters don’t do this. They just assume that they are correct in estimating how close to failure they are, and they never really test themselves. So if you’re not trained very close to failure, I also highly recommend that occasionally you do go to failure and you fact check yourself. Ask yourself – when you think I can only do three more repetitions, really push yourself and see if you could do 3 or maybe 4, 5 or maybe 7.

The second study, still in pre-print, and again on strength trains individuals, men and women, is one of the most rigorous studies I’ve seen this year.

The researchers had the lifters train one of their legs with a lower volume, 6 to 8 sets per week, and the other leg with a higher volume 12 to 16 sets per week. Each individual trained like this for 11 weeks, then had a 6 to 8 week period in which they did their normal training and then repeated the program for another 11 weeks. So every lifter was both their own control group, with one leg doing one volume and the other like doing the other volume, and they repeated the program again for a total duration of 22 weeks per subject. And within-subject study design like this is extremely rigorous because every subject is their own control across time and also across their genetics, motivation level and nutrition.

A huge benefit of having lifters be their own control group, with one leg doing one type of training and the other like doing another type of training, is that both legs have the same genetics, they get the same nutrition, and presumably the motivation level is the same when they’re training both of their legs. These are huge advantages compared to studies that look at different individuals performing a higher versus a lower training volume. All lifters trained twice a week and left 2 reps in reserve doing their sets.

The result: higher training volumes quite consistently and considerably increased muscle growth in almost all of the subjects. Because every subject completed the program twice for 11 weeks we can also say which subjects reliably responded better to higher or lower training volumes. There was a tiny minority of subjects who may have responded better to the lower volume, but the vast majority of subjects responded better to higher volume. This means that for most trained lifters, the optimal training volume is probably closer to 16 sets per muscle group per week than to eight sets per muscle group per week. At least if they’re not cutting.

Strength gains follow a similar pattern, but statistically it was harder to determine if the strength gains were truly greater in the higher volume training group. The lower benefits of training volume for strength development versus muscle growth are also seen in other studies. However, they are mostly the result of strength development in the short term being highly neurological in nature. In the long term, muscle growth and strength development correlate quite strongly in the best controlled research.

And in case you’re wondering if the higher training volume simply didn’t produce more edema, instead of actual contractile muscle growth, I explain that in this video. The short answer is – probably not. The muscle growth seems to be real contractile tissue growth. And I note that in the current study, muscle growth was measured in cross-sectional area and in muscle thickness, and the results were similar for both measurements of muscle size.

A final interesting finding in this study is that the researchers could not identify solid evidence of genetic outliers or snowflakes. In any study, there was always a response continuum. Some people gain more muscle than others. And there may also be a differential response to how well people tolerate higher training volumes. People vary in recovery capacity, and some people can handle more volume than others. However, it’s quite difficult to determine if you truly are a snowflake. I know your mama said you were special, but in this study the researchers found that subjects that seemed to respond better to the lower training volume the first time around actually did not the second time around, in many cases. And this occurs in an extremely rigorous study.

A big part of the reason for this is simply measurement error. Even when you were measuring muscle size with ultrasound measures you see that sometimes the measurement is simply wrong. Then there’s just a variation in how hard you train and how much muscle you can gain throughout different periods of time, even in a within subject design. What it means for you in a non controlled study, not using ultrasound measures, it is exceeding difficult to determine if you respond better or different than the average individual to higher versus lower training volumes.

I think many non evidence based lifters greatly overestimate the knowledge they can gain from simply trying a program out and seeing how they respond. First of all, you really don’t know how you respond because if you’re not measuring muscle growth with ultrasound or MRI it’s exceedingly difficult to really know if you’re getting bigger. And even if you are getting bigger, is it because of this program or is it because you slept better, because your nutrition was better, or any of the other million factors that always change in our daily lives? And that’s why it’s so important to look at scientific research so that we can see under rigorously controlled circumstances what training variables optimize muscle growth, strength development, and all the gains we care about.

In conclusion, going back to the original question of the video – high intensity training and other methods that have you trained very close to failure but with few sets are not nearly as reliable a method as doing more sets and potentially even staying a little bit further away from failure. Volume in general is a much stronger driver of muscle growth than training proximity to failure. However, multiple roads lead to Rome. You can likely compensate for a lower training volume by training harder if that means that you’re actually getting more repetitions in every set.

I hope this knowledge helps you with your training program design, and if you want more of this evidence based fitness content I’d be honored if you like and subscribe. If you want to know absolutely everything there is to know about muscle growth, strength development, and how to optimize your gains: Check out my online PT course. It will teach you absolutely everything a serious lifter wants to know.