Muscle growth, metabolic stress and mechanical stress
I’m a sucker for metabolic stress. If after a workout I am not short of breath, do not feel the sweat seeping down my temples, do not acidify from lactic acid combustion or rejoice over the shine of a pump, I get the training equivalent of blue balls.
Just like real blue balls, it’s not dangerous, but I’m a little grumpy until I find a sweet ejaculation. So fill me up with work, please. Let my breath – a mutant cross between a mule and a beaver – shine.
Therefore, it piqued my interest to read about the 3/7 method. It is a set-rep program developed by the French strength trainer Emmanuel Legeard in the early 2000s. It combines relatively heavy weight (mechanical stress) with very short rest periods (metabolic stress).
It has a few things in mind. One, it is among the most time-efficient methods available, and secondly, it has solid research to back up its muscle-building and muscle-strengthening credentials.
The short intervals used in the 3/7 method are believed to induce a greater amount of cumulative fatigue-related metabolites such as lactate, hydrogen ions and inorganic phosphate.
Sounds vaguely familiar? It is exactly the mechanism that is attributed to the success of training for blood flow restriction (when you wrap elastic around a muscle before putting).
The incremental organization of reps in each set is also thought to play a role in inducing a greater accumulation of metabolites, especially at the 5th set (of the first “round” of reps), the 10th set (at the end of the second set). ). round), and the 15th set (which you hit at the end of the third round, provided you have not already made a mistake).
All this metabolic stress then triggers the anabolic signaling that leads to muscle hypertrophy.

Only two studies have been conducted using the 3/7 method (the first was chosen as the finalist for “Paper of the Year” at the American College of Sports Medicine’s annual meeting), but both showed convincing results.
Laurent, et al., Compared the 3/7 method with two more traditional training methods. They divided 38 healthy young men into three separate groups. Each group trained bench press twice a week for 8 weeks:
- Group A used a 4×6 (4 sets of 6 reps) protocol.
- Group B used an 8×6 (8 sets of 6 reps) protocol.
- Group C used the 3/7 protocol.
Each group used 70% of 1RM and rested 150 seconds between sets (or, in the case of the 3/7 method, between rounds).
- The 4×6 group improved 1RM by 21.8%.
- The 8×6 group improved 1RM by 35.9%.
- The 3/7 group improved 1RM by 29.8%.
While the 3/7 group did not “win” the competition, it still showed quite strong results. Also keep in mind that this study only used one round of 3/7 training instead of the 3 rounds originally proposed by Emmanuel Legeard when he developed the method.

Stragier, et al. also compared the 3/7 method with another classic set / rep approach (8×6), this time aimed at biceps curls and evaluated both strength and muscle thickness.
43 untrained subjects, divided into two groups, trained machine biceps curl twice a week for 12 weeks. However, in contrast to the Laurent study described above, the subjects in this study completed two rounds of 3/7 training instead of one.
As in the Laurent study, both groups used exercise weights of approximately 70% of 1RM.
This time 3/7 came out on top. This resulted in 75% greater biceps growth and 83% greater strength gain than the 8×6 protocol, probably due to the extra round of metabolic stress induced by using a second round of 3/7 training.
The studies are quite convincing, but you may have noticed that they did not use experienced weight trainers. It makes the results a little worse because, well, you can train beginners with Campbell’s soup cans and then develop them to use Progresso Rich and Hearty soup cans, and even that amount of anemic training will result in some significant gains in strength and hypertrophy.
Nevertheless, the hypothesis behind this type of metabolic stress training works correctly. It can work well with experienced trainees, especially if they do three rounds with the 3/7 method (for a total of close to 75 reps!) Instead of the one or two that were used in the studies.
A clear advantage of the 3/7 method that you may not have considered is time efficiency. A round of 3/7 training takes somewhere between 2 and 3 minutes, while doing 8 sets of 6 will probably take around 20 minutes.
Adding more rounds of 3/7 training will of course add to the 2 or 3 minute total, but it still provides a fairly quick workout.
If you want to take 3/7 training out on a round, respect these critical points:
- Choose the right weight (about 70% of 1RM, which is usually equivalent to a weight you can do for 12 reps or so). You will know that you are using the right weight if you fail to hit the prescribed reps on the last one or two intra-sets of round two or three.
- Allow only 15 seconds between each “intraset” and allow 150 seconds (two and a half minutes) between rounds.
- Experienced trainees will probably have to go 3 rounds to reap the maximum benefits.
And although the studies on the 3/7 method only used two exercises (smith machine bench press and machine biceps curls), there is no obvious reason why it should not work well with any body part or any conventional training, possibly with the exception of nut. busts such as squats or deadlifts.