Photo of a woman with handweights
It's not how much you can lift, but whether you are willing to lift it enough times to get the benefit that counts!

Light weights work just as well as heavy ones to build muscle

1 May, 2012

Natural Health News — Lifting less weight more times is just as effective at building muscle as training with heavy weights, a study finding that turns conventional wisdom on its head.

The key to muscle gain, say Canadian researchers at McMaster University, is working to the point of fatigue.

“We found that loads that were quite heavy and comparatively light were equally effective at inducing muscle growth and promoting strength,” says Cam Mitchell, one of the lead authors of the study.

The research, published in the Journal of Applied Physiology, challenges the widely accepted dogma that training with heavy weights – which can be lifted only six to 12 times before muscle fatigue sets in – is the best way to achieve muscle growth.

“Many older adults can have joint problems which would prevent them training with heavy loads,” says Mitchell. “This study shows that they have the option of training with lighter and less intimidating loads and can still receive the benefits.”

For the study, a series of experiments were conducted on healthy, young male volunteers to measure how their leg muscles reacted to different forms of resistance training over a period of 10 weeks.

Finding the right weight

The researchers first determined the maximum weight each subject could lift one time in a knee extension. Each subject was assigned to a different training program for each leg.

In all, three different programs were used in combinations that required the volunteers to complete sets of as many repetitions as possible with their assigned loads – typically eight to 12 times per set at the heaviest weights and 25-30 times at the lowest weights.

The three programs used in the combinations were:

  • one set at 80% of the maximum load
  • three sets at 80% of the maximum
  • three sets at 30% of the maximum

After 10 weeks of training, three times per week, the heavy and light groups that lifted three sets saw significant gains in muscle volume – as measured by MRI – with no difference among the groups. Still, the group that used heavier weights for three sets developed a bit more strength.

The group that trained for a single set showed approximately half the increase in muscle size seen in both the heavy and light groups.

“The complexity of current resistance training guidelines may deter some people from resistance training and therefore from receiving the associated health benefits,” says Stuart Phillips, a professor in the Department of Kinesiology and supervisor of the study.

“Our study provides evidence for a simpler paradigm, where a much broader range of loads including quite light loads can induce muscle growth, provided it is lifted to the point where it is difficult to maintain good form.”

Lift ’til you can’t lift no more

These findings echo those of a 2010 study – also by McMaster researchers.

In this study the scientists used different weights that represented a percentage of what the subjects could lift. The heavier weights were set to 90% of a person’s best lift and the light weights at just 30%. The 90-80% range is usually something people can lift from 5-10 times before fatigue sets in. At 30%,  that subjects could lift that weight at least 24 times before they felt fatigue.

What they found was it’s not the weight that you lift but the fact that you get muscular fatigue that’s the critical point in building muscle. In other words, instead of straining to lift heavy weights, you can get the same benefit from hefting something much lighter – but you have to lift it until you can’t lift it any more.