Can High Reps at Low Weight Build Muscle Mass?

If you talk to most lifters who are trying to gain strength or muscle mass, they will explain that you need to lift 1-5 reps at a heavy weight in order to gain strength and 6-12 reps at al slightly lower weight for building muscle mass. Are those numbers etched in stone? Could a different repetition range offer some benefits to strength and muscle mass?

This is what researchers at Canada’s McMaster University sought to figure out. They took two groups of experienced male lifters and put them on a 12 week, whole body program. The first group lifted lighter weights (approximately 50% of their maximum strength) for sets ranging from 20-25 repetitions. The second group heavier weights (up to 90% of their maximum strength for 8-12 repetitions. The two groups always lifted to the point of momentary muscle failure.

“Fatigue is the great equalizer here,” says Stuart Phillips, senior author on the study and professor in the Department of Kinesiology. “Lift to the point of exhaustion and it doesn’t matter whether the weights are heavy or light.”

The researchers analyzed muscle and blood samples. They found the gains were virtually identical with muscle mass and muscle fiber size between the two groups.

“At the point of fatigue, both groups would have been trying to maximally activate their muscle fibres to generate force,” says Phillips, who conducted the work with graduate students and co-authors Rob Morton and Sara Oikawa.

While many elite athletes will stick to their traditional weightlifting program, they would also benefit from heeding results of the study.

“For the ‘mere mortal’ who wants to get stronger, we’ve shown that you can take a break from lifting heavy weights and not compromise any gains,” says Phillips. “It’s also a new choice which could appeal to the masses and get people to take up something they should be doing for their health.”

What are you to do?

Take a break from the heavy lifts. Incorporate more repetitions (20-25 reps) and you will get the same benefits as you did with your original workout. The key ingredient is to lift to momentary muscle failure. (See: We Strive To Fitness Failure).

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