4×4 Builds bigger arms than 3×12, new study finds

Chapters:

00:00 Intro

00:06 The new study

00:47 “Strength” group results

01:36 “Hypertrophy” group results

03:19 My Online PT Course

03:39 “Hypertrophy” group results

05:24 Conclusion

06:28 “Power” group results

06:52 Outro

Transcript:

Many people still have outdated ideas of what’s training for strength vs size should look like. In a new study, the researchers had a group of novice level trainees bench press three times per week with different repetition schemes. All training groups rested at least three minutes between sets. The “strength” group did four sets of four repetitions, increasing the load after they hit four repetitions on the last set. The “hypertrophy” group did three sets of 8 to 12 repetitions, aiming to hit failure in the third set and increasing the load after hitting 12 repetitions in set 3. The “power” group did four sets of 6 to 7 repetitions at a mere 40% of 1RM aiming for maximum effort and performing bench throws. And then the control group did four sets of absolutely nada.

After eight weeks the strength group did not, in fact, gain more strength than the hypertrophy group. In more advanced lifters we do generally see that higher training intensities leads to greater strength development. For 1RM strength development in particular, which is often what we imply when we say strength, we’re talking about maximal strength, the closer you work towards your 1RM typically the better the strength gains, but this is a finding that is mostly applicable to more trained lifters. In novice level or untrained lifters we don’t see this very strongly yet. That’s why I typically favor starting with a little bit higher repetitions for exercises where this doesn’t turn into cardio like squats, you don’t want to do sets of 20 for squats, but for exercises like bench presses I typically favor sets of 8 to 12 repetitions more for novices than sets of five, because the risk reward is just not there for going heavy.

The “hypertrophy” group also did not, in fact, gain more muscle mass than the strength group. In fact, arm lean mass increased significantly more in the “strength” group than the “hypertrophy” group. Now, segmental Dexa scans, which is what was used here, are not terribly accurate. So when you do a Dexa scan and I see this all the time in clients, people get worried about, oh my left arm is a little bit bigger than my right arm. The level of precision needed to really diagnose that is just not there with a Dexa scan. The total full body estimate is pretty okay, but the segmental estimates of your trunk versus your arm, left arm versus the right arm, it’s not very accurate. So I wouldn‘t put a lot of stock into this, and also we saw that the total lean body mass and trunk lean body mass did not significantly differ between the groups.

Still, a trend towards greater arm gains or generally some trend towards greater gains in the strength group is not completely unexpected because they did four sets instead of three sets. They also did sets of four instead of sets of 8 to 12, but most research finds that within the range of about 4 to 30 plus repetitions, training intensity does not in fact influence muscle hypertrophy. You can go very high in repetitions because as you get fatigued, the higher threshold motor units have a lower recruitment threshold, so the bigger guys and the higher threshold motor units with more of the type two muscle fibers that have most of the growth potential, they do kick in at the end of the set, and you will still recruit them unless it really turns into cardio. So if you do a set of 50 on the squats, it’s most likely very suboptimal for muscle growth because you run into energy depletion, cardio oxygen deprivation, rather than being limited by muscle recruitment. But you can go very high in repetitions generally and still maximize muscle hypertrophy.

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Likewise, the lower end of the hypertrophy zone is a lot lower than commonly believed in bodybuilding circles. 6 to 12 repetitions or so is kind of the norm there, or used to be, and this has been quite thoroughly debunked. It doesn’t make any sense in terms of mechanical tension, which is the primary signal for muscle hypertrophy, that lower repetitions would be worse than higher repetitions. A lower repetition with a higher load by definition almost puts more tension on the muscle fiber. It requires higher force outputs, and mechanical tension is the internal force output in the muscle, so heavier weights lead to more tension. Now they also lead to less time under tension, and this trade off is basically where we see that the repetition range that you use doesn’t really matter for muscle hypertrophy in the vast majority of studies. You can either get a lot of time under tension with lower tension, or you can get very high tension for a shorter period of time. That is the trade off with lower reps versus higher reps.

Now we do see that this breaks down, like I said, at the upper end things just turn into cardio. At the lower end there does seem to be kind of a minimum time under tension that you need per set to get a robust signal for muscle hypertrophy, and that seems to be around 4 repetitions, which is probably why this study was confusing to a lot of people. When we look at studies where people, for example, do 1RMs, one single one rep max does not generate as much muscle hypertrophy as a set of, say, ten repetitions. The time under tension is likely just not there, even though the tension for that one repetition is very high. So this study essentially investigates the dual hypothesis of what the influence of sets and rep range are, and it supports that sets are most likely a lot more influential than repetition ranges. So in that sense, it’s not too surprising that the strength group, by virtue of doing another set, gains more muscle mass than the hypertrophy group, at least on one of the measures.

If we combine this new study’s results with that of the total literature, we can come to a couple of take home messages. First, lower repetitions are generally better for strength development, but beginners don’t need this yet. Lower repetitions are better for strength development because you are essentially training for the test, at least if you are defining strength as one repetition maximum strength. You get a very high force output, very high muscle activity, and this is good for neural learning, for strength development, which is in large part a skill specific to velocity, the movement that you’re doing, the repetition tempo that you’re using. Strength is very much specific, and it’s a matter of coordination. Your brain, your motor cortex, learns to coordinate your muscles very well. And then there’s the muscle mass component for which the take home message here is that repetition ranges are almost irrelevant, at least within the range of 4 to 30 repetitions for muscle hypertrophy.

Set volume is much, much more important, which is why it can even be the case that something like 4×4 which most people would associate with a strength workout can result in more muscle hypertrophy than 3 sets of 12, which most people would associate more with a hypertrophy workout. And if you recall, this study also had a power group. Well, the power group made terrible gains. I think power training is basically useless for non athletes if you are a power lifter or a shotput thrower, discus thrower, something like that, then power work might have a place in your program. But for most recreational trainees that are mostly interested in looking good naked and getting stronger in general terms, you really don’t need any power work in your workouts. It’s largely a waste of time.

I hope this research update and these tips help you with your fitness journey. If you’re interested in more evidence based content like this, I’d be honored if you like and subscribe. And if you want a detailed course into everything you need to know to maximize muscle hypertrophy, strength development and fat loss, check out my online course in the description below.