August 16th, 2010
04:35 PM ET

What builds more muscles – weight or repetitions?

Straining and groaning under a heavy weight to pump those muscles might be unnecessary, according to a study released from a Canadian university.

While body builders and muscle fanatics may load up their weights, it could be just as useful to use a lighter load, but do more repetitions until the muscle becomes tired, kinesiologists at McMaster University suggested.

The findings are published in PLoS ONE.In the study, the authors had 15 men perform leg extensions by kicking their knees against a weight while seated. They were randomly assigned to either lifting their legs using a weight that was 90 percent of their best lift or 30 percent.

The participants with the heavier load could lift about five to 10 times. Those who lifted at 30 percent of the load could lift about 24 times. A sample of their muscle was taken.

While both exercises produced proteins that help build muscles, the people who lifted at 30 percent to the point of fatigue (where the limbs start to jiggle and tremble) produced slightly more muscle than those who lifted at 90 percent, said Stuart Phillips, associate professor of kinesiology at McMaster University.

“We had a strong idea based on the understanding on basic muscle physiology that your muscle can’t tell the difference between 30 percent or 90 percent of the load- all it knows is there is a load or fatigue,” said Phillips.

This small, initial study showed that even at a lesser weight, the muscle-building proteins developed at a slightly faster rate. These proteins stack likes bricks, to produce muscles - the more proteins there are, the larger and more pronounced those muscles become.

This doesn’t mean that pumping a two-pound barbell a thousand times would give you guns of steel.

“Clearly, there’s a threshold of fatigue you need to achieve,” Phillips said. “With very low loads, we have yet to see how low you can go.”

This could benefit people who might be older, who are not able to pick up heavy weight. It could save the wear and tear and relieve muscles, joints, tendons, ligaments and bones.  Longer-term studies will be conducted to test these initial results, Phillips said.

“Instead of going to the gym, working and lifting some heavy weight that you grunt and groan to get off the ground, you can pick a lighter weight until the last repetition is still hard,” he said. “It’s still hard work.”

soundoff (122 Responses)
  1. Jason

    It sounds like the German Volume Training protocol to me. Google it and you'll see. It's a program where you can add mass faster. Basically low weight with 10 sets of 10 reps. Initially, you will not feel fatigued till you hit the 7th set that is if you are only using 60% of you 1rep max. Moreover, training is every other day to maximize growth.

    December 30, 2015 at 15:29 | Report abuse | Reply
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