When training to build strength or muscle, most people use a sets and reps structure.
For instance, you may perform 3 sets of 6 reps on the bench press in a session.
However, something called the 3/7 method seems to be gaining some degree of popularity in recent years.
This method appears to have originated from a 2005 French Fitness book.
The 3/7 method has you select a 70% one-rep max load (which equates to a load you can generally perform a maximum of 12 repetitions with).
With this 70% one-rep max load, you perform 3 reps, rest for 15 seconds, perform 4 reps, rest for 15 seconds, perform 5 reps, rest for 15 seconds, perform 6 reps, rest for 15 seconds, and then perform a final 7 reps.
Generally, the first 3 and 4 rep sets are quite easy. But, the 5, 6 and 7 rep sets are pretty much near or to failure.
Could doing this be superior for muscle or strength gain?
Let us examine the evidence.
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3/7 Method: The Research
A study by Stragier et al. had 43 previously untrained men train a machine biceps exercise twice per week for 8 weeks.
A normal group, each session, performed the exercise with 8 sets of 6 repetitions with a 70% one-rep max load, using 2.5 minutes of rest between sets.
A 3/7 group, each session, with a 70% one-rep max load, performed the 3/7 method for 2 bouts, separated by 2.5 minutes of rest between bouts. Just to emphasize this, they repeated the 3/7 method twice in a session, with a 2.5-minute rest interval between them.
For both groups, if a subject was unable to complete their respective prescribed protocol, assistance was provided.
On the other hand, if a subject could complete their respective prescribed protocol for two sessions in a row, they increased the load they used by 2.5-5%.
After the 8 weeks of training, increases in one-rep max on the machine biceps exercise were greater for the 3/7 group.
Furthermore, increases in biceps long head thickness (which was averaged out from an upper, middle, and lower region) were also greater for the 3/7 group.
Before exploring these hypertrophy results further, I think it’s first worth looking at the strength results a little further.
A Closer Look at the Strength Results
Despite the study finding greater increases in one-rep max with the 3/7 method, the results do not necessarily suggest the 3/7 method is optimal for strength gains.
Remember, 2 bouts of the 3/7 method were compared to 8 sets of 6 reps with a 70% one-rep max load.
For maximizing your one-rep max on an exercise, training with heavier loads is likely better.
For example, Schoenfeld et al. found training sets on the bench press and back squat with 2-4 reps with a roughly 90% one-rep max load produced greater one-rep max gains on the bench press and back squat compared to training them with 8-12 reps with a roughly 75% one-rep max load.
Therefore, if the 3/7 method was compared to training with 90%+ one-rep max loads, I think it’s highly likely the 3/7 method would be inferior.
A Closer Look at the Hypertrophy Results
Let us now dive into the hypertrophy results.
As we noted, the 3/7 group experienced more gains than the normal group.
However, some of you may be questioning the normal group’s training program.
8 sets of 6 repetitions with a 70% one-rep max load sounds a little odd and doesn’t really sound like something you would do to build muscle.
Perhaps if the 3/7 method was compared to a more traditional hypertrophy protocol, say 3 to 5 sets of 8-12 repetitions performed to or near failure, the results would not have been so favorable for the 3/7 group.
This was actually my initial thought when I first read the study. However, upon closer analysis, 8 sets of 6 reps with a 70% one-rep max load is probably quite effective for building muscle, meaning this may not be a problem.
Firstly, a 70% one-rep max load is perfectly fine for building muscle, as we’ve explored in previous rep range articles.
With a 70% one-rep max load, you can generally perform around a maximum of 12 repetitions to failure.
The normal group only performed 6 reps per set, meaning their 1st set would have been roughly 6 reps away from failure.
Now, due to the effects of cumulative fatigue, the following sets would have been closer to failure. Let us assume that each successive set puts a subject 1 rep closer to failure than the previous set. This would mean the 2nd set was performed 5 reps away from failure, the 3rd sets 4 reps away from failure, the 4th set 3 reps away from failure, the 5th set 2 reps away from failure, the 6th set 1 rep away from failure, the 7th set to failure, and the 8th set to failure.
Of course, this is far from perfect. But for our purposes, it will work.
When broken down in this way, it’s hard to call this protocol meaningfully suboptimal for building muscle.
The reason I say this is because training to failure does not appear to be neccessary for hypertrophy. A fair few papers demonstrate that training 3 to 1 rep away from failure per set is as effective for hypertrophy to training to failure.
Out of the 8 sets for the normal group, 5 sets would likely have been within 3 reps from failure.
Furthermore, there actually is some evidence training 5 reps away from failure could also be as effective as training to failure for hypertrophy. So, perhaps even more of the normal group’s sets could be classified as optimal for building muscle.
On the basis of all of this, I think this study probably did find the 3/7 method to truly have some sort of enhanced benefit for muscle hypertrophy.
Why could this be?
Could there be something special amount incrementally performing more reps with a given load while using short rest durations.
The authors of the study speculated the 3/7 method superiority could be explained by it producing more metabolic stress.
Metabolic stress is the build-up of metabolites (which are products of cellular processes) such as lactate within muscles.
However, I’m skeptical of this simply because the role of metabolic stress in muscle growth is far from clear. There are numerous cases in which more metabolic stress does not result in more muscle hypertrophy.
All in all, I don’t know if there are any legitimate reasons as to why the 3/7 method could build more muscle.
Further Considerations and Research
Moving on, it’s essential to recognize this is only a single study. There are no other studies, as far as I’m aware, exploring the effects of the 3/7 method on muscle hypertrophy.
A single study is nothing near definitive and conclusive evidence.
Because of this, we simply cannot be anywhere close to certain that the 3/7 method truly builds more muscle.
Furthermore, the study was conducted on previously untrained individuals and so we do not know if this study can be replicated in trained individuals.
3/7 Method Is Comparable to Rest-Pause Training
The closest thing I can think of to the 3/7 method is rest-pause training.
Rest-pause training involves performing reps to failure with a given load, then resting for 15 to 20 seconds, and performing further repetitions to failure with that same load. This can be repeated however many times you wish. Of course, the similarity to the 3/7 method lies in the short rest between repetition bouts.
Could the rest-pause training research provide greater insight into the potential hypertrophic effects of the 3/7 method?
By my count, there are only two studies that have technically explored rest-pause training.
Enes et al. had 19 men with at least 2 years of training experience perform the back squat, leg press, and leg extension, twice per week for 8 weeks.
A normal group trained each exercise per session with 4 sets of 12 repetitions with a 70% one-rep max load, using 2 minutes of rest between sets.
A rest-pause group performed 10 repetitions with a 75% one-rep max load, rested 20 seconds, and then performed 6 further repetitions with the same load. For each exercise, they performed 3 of these rest-pause sets, with 120 seconds of rest between sets.
At the fifth week of training, both groups increased their training loads by 5%.
By the end of the study, increases in lateral thigh thickness (which includes the vastus lateralis and vastus intermedius), at 30%, 50%, and 70% of the thigh bone length were statistically similar between both groups, suggesting rest-pause provides no muscle growth benefit.
Having said this, the rest-pause group did not take their repetitions to failure, and only one extra bout of repetitions was performed per set, so this is potentially a limitation.
Another study by Prestes et al. has 18 individuals with at least 1 year of training experience perform a range of exercises four times per week for 6 weeks.
A normal group performed each exercise per session with 3 sets of 6 reps with an 80% one-rep max load, using 2-3 minutes of rest between sets.
A rest-pause group, for each exercise per session, performed reps to failure with an 80% one-rep max load, and then rested 20 seconds before performing further reps to failure. They did until they reached a total of 18 reps.
After the 6 training weeks, increases in chest and arm thickness were similar between both groups, but increases in quadriceps thickness were greater for the rest-pause group.
So the results of this study partially suggest rest-pause training can enhance muscle hypertrophy.
However, there is a limitation. It seems the normal group did not apply progressive overload.
Recall they were performing 3 sets of 6 reps with an 80% one-rep max load. In the early stages of the study, this likely would have meant subjects were roughly 3 to 1 reps away from failure per set, which we know is fine for muscle hypertrophy.
However, as they get stronger from these initial training sessions, this 80% one-rep max load would no longer have actually been their true 80% one-rep max, rather less.
Given no progressive overload was applied, meaning they did not readjust their 80% one-rep max load, they were probably training with more than 3 reps away from failure per set as the study progressed.
On the other hand, given the rest-pause group was performing all their repetitions to failure, progressive overload would naturally have been applied.
Due to this limitation, this study should be considered with caution.
So all in all, the rest-pause research seems too limited and insufficient to provide us with any further clues on the 3/7 method.
To conclude the article, a single study does seem to suggest the 3/7 method can build more muscle. However, given it is only a single study, we cannot be certain the 3/7 method truly builds more muscle, hopefully future research can provide us with more clarity.
Ultimately, there probably is no terrible downside to experimenting with the 3/7 method if that’s something you’d think you like to do.
One thing I’ve yet to mention is the 3/7 method can be considered quite time-efficient. By my calculations, in the Stragier et al. study, excluding the warm-up, the 3/7 group would have been training for 5-6 minutes per session, while the normal group would have been training for 19-20 minutes each session.