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For those of us who dream of packing on a little extra muscle, or simply hanging on to what we’ve got, there was tantalizing news at the American College of Sports Medicine’s annual conference in San Diego earlier this month.

One of the society’s “Paper of the Year” selections, chosen for their impact and research significance, touts a new and uniquely effective strength training protocol called the 3/7 method. It’s the latest in a long line of supposed muscle-building breakthroughs – and the good news is that it works. But the more interesting question is why it works and what that tells us about the real keys to building muscle.

The paper has its origins in a meeting between a Swiss track and field coach and a Belgian neurophysiologist. Jean-Pierre Egger was a two-time Olympic shot-putter, and is the coach of multiple world champions including four-time Olympic shot put medalist Valerie Adams. He told Jacques Duchateau, a researcher at Université Libre de Bruxelles, about a new approach he’d been using that enabled his athletes to maximize strength gains with less training time and effort.

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Duchateau decided to put this new protocol to the test in his lab. The 3/7 method, originally developed by French strength coach Emmanuel Legeard, involves lifting a weight that’s about 70 per cent of your one-rep max (or, equivalently, a weight that you could lift about 12 times before reaching failure). You lift it in five sets of 3, 4, 5, 6, and 7 reps, with just 15 seconds of rest between each set.

The protocol interested Duchateau because it seemed to combine the best of two different ways of building muscle. The relatively heavy weight puts mechanical stress on your muscle fibres, and the very short rest period starves the muscles of oxygen and imposes metabolic stress. Each of these factors independently triggers muscle growth, Duchateau believes.

The award-winning paper, which Duchateau and his colleagues published in Exercise and Sport Sciences Reviews, summarized a series of experiments pitting the 3/7 method against various other protocols for bench press. For both strength and muscle growth (but not for explosive power), it outperformed 4 sets of 6 reps with 2.5 minutes of rest between sets, and produced similar results to 8 sets of 6 reps, all with the same weight.

The key advantage, as both Egger and Duchateau point out, is efficiency. A single exercise with the 3/7 method takes about 5 minutes, compared with more than 20 minutes for 8 sets of 6 reps.

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But is the 3/7 approach better than the alternatives, or just different? If efficiency is what you’re after, a Dutch company called fit20 offers a once-a-week program that involves just one set of 4 to 6 ultraslow reps of each exercise. A multiyear analysis of nearly 15,000 people using that system, published by Solent University researcher James Steele, found typical strength gains of about 30 per cent after a year.

As for the supposed magic of combining mechanical and metabolic stress, McMaster University researcher Stuart Phillips – who, as it happens, received the ACSM’s Citation Award for significant contributions to exercise science at this month’s annual conference – remains skeptical. After all, he points out, track runners induce plenty of metabolic stress while running interval workouts, but they don’t develop massive leg muscles.

A series of studies by Phillips and others over the past decade has shown that many different workout routines lead to similar muscle and strength increases. The key commonality: that you approach (though not necessarily reach) momentary failure at the end of each exercise. Light weights, heavy weights, short rests, long rests – you can tweak the variables to your heart’s content as long as the end of the set feels hard.

The 3/7 approach definitely ticks that box: If you’ve picked the appropriate weight, you’ll hit failure in the last two sets, Duchateau says. So if you’ve hit a plateau or are looking for some variety in your workouts, give the new method a try. Or, if you prefer, stick with your old method. Either way, Phillips says, the real magic ingredients remain the same: effort and consistency.

Alex Hutchinson is the author of Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance. Follow him on Twitter @sweatscience.

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