Was Mike Mentzer right about arm training? (New study)

Chapters:

00:00 Intro

00:19 Study design

01:17 Study results

02:10 Caveats

03:20 Overall literature

04:19 Conclusions

06:26 Outro

Transcript:

How many arm isolation exercises do you need to build muscle as fast as humanly possible in your biceps and triceps? Bodybuilders like Arnold Schwarzenegger famously did two or more, yet bodybuilders like Mike Mentzer and Arthur Jones often did zero. So who’s right? A new study put it to the test.

The researchers had a group of lifters train one of their arms with just one biceps curl and push downs. The other group did two different variations of arm isolation exercises out of a group of three. Specifically for biceps they did dumbbell curls, preacher curls, and incline curls. For triceps, they did skull crushers, French presses, and kickbacks. I would know that technically they said they were doing barbell biceps curls, but I highly doubt that they were doing barbell bicep curls with one arm. Also, it’s a little bit odd that the control group did one exercise, push downs, and then push downs were not included in the list of the three different exercises that the variety group was doing.

Anyway, the study is still a comparison of just doing one biceps and triceps isolation exercise versus rotating through a set of three different ones and doing two different ones every week. So more variety vs. less variety. And importantly, to keep the programs realistic the subjects also did barbell bench presses and pull downs. So they had one compound exercise and at least one isolation exercise.

After eight weeks, muscle growth was around 3% in both of the groups, suggesting that the added arm training variety did not boost muscle growth. However, it’s worth noting that beyond the typical limitation of an eight week study, the lifters only had six weeks of training experience. So when we look at more advanced lifters over the longer term, and also probably doing higher volumes because the fractional training volume was only eight sets per week, if we count the compound volume as half, then it’s possible that higher volumes and more exercise variety become more beneficial.

Speaking of training volume, there was also a group in the study that increased their training volume on the arm isolation exercises from 4 to 6 sets per session. There was also a group that did both. They added volume and they added exercise variety. None of those groups grew significantly more than the control group that just did one exercise for four sets. All exercises I would note were performed to failure.

So far, these findings seem to strongly support the more minimalist type training from Mike Mentzer and Arthur Jones. However, a huge caveat that the researchers themselves made explicit is that when you increase training volume from 8 to 12 fractional sets per week per muscle group, as this study did, then we would expect only 0.9% additional muscle growth, based on the latest meta analysis of the literature, Pelland et al. And this was actually below the error margin of the Dexa scans. So this study had no chance of detecting a small possible benefit. And in fact, that no chance of detecting the likely small benefits that this additional training volume should have caused.

This is especially true in this study, where they were using one minute rest intervals and going to failure. If you’re using one minute rest intervals and training to failure, and you are already doing four sets, then set five and six logically had a very little volume, and you cannot expect them to contribute a lot of additional muscle growth. If I had been involved in the research design, I would have personally skipped the six week introduction training and just ran a 14 week study and only look at volume or exercise variety. I think what the researchers currently did is a bit of an overreach.

Nevertheless, both of the findings do fit with the overall literature. As I said, the extra growth expected from going from 8 to 12 sets per week per muscle group would not have been detectable in this study. And it’s not a massive effect, especially again when you’re already doing four sets to failure with one minute rest intervals. Extending your volume beyond that for the same exercise has very little additional effect on muscle growth.

Moreover, when we specifically look at arm training and exercise variety, multiple studies have found that adding arm exercise variety beyond one compound and one isolation exercise really doesn’t add much at all. Even when you don’t control for volume, multiple studies have found that adding an arm isolation exercise to a compound exercise adds minimal extra gains. However, in my PT course we’ve done an in-house meta analysis of this literature, and we found that when you don’t control for volume, at least there is additional muscle growth in the groups doing added arm isolation exercises compared to just doing compound exercises.

So what conclusions can we draw from this and other research? Well, first of all, it’s clear that your compound exercises definitely count towards your training volume. There is debate in bodybuilding circles where you should be counting your compound and multi joint exercises towards your arm training. Yes, you absolutely should. The question is more if it’s even needed to do arm isolation training to begin with. Compound exercises absolutely count and ideally you count their fractional training volume. In my PT course, we have an overview of how much every exercise trains, every muscle group based on the best available research. Ideally, you count your volume like that. For simplicity though, what you can also do is you just count compound exercises in their entirety or you count them half. Many studies use this method, and it’s also reasonably accurate.

As to how much exercise variety you need for your arms, the best research does lean in the direction of needing at least one good arm isolation exercise, in large part also because compound exercises simply do not allow you to maximize muscle tension over the entire muscle length of the triceps and the biceps, especially for the triceps, where it’s hard to achieve that in the long head with compound exercises. So I do recommend that you get at least one arm isolation exercise for both the biceps and the triceps. However, any benefits of further exercise variety appear to be absolutely minimal.

So the answer to how many exercises you need is basically the same as the answer to how many romantic partners you need. You just need one – good one, and then get really good at that one until you get injured and you have to switch. You need one for the biceps and the triceps, not just one in total. So maybe it’s not the best analogy, but anyway.

Take home message #3 is that when you’re already doing four sets for an exercise, going to 5 or 6 sets for that exercise, especially if you’re training to, or very close to failure, does not give you much additional muscle growth. This is also clearly in line with most research. You’re much better at that point of doing an additional exercise or moving that volume, at least to a different day. The extra volume you get when you’re already in such a fatigued state is minimal, so you get the very little additional muscle growth.

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