Lifting less weight more times is just as good at building muscle as doing it with heavy weights, says a new finding.

"We found that loads that were quite heavy and comparatively light were equally effective at inducing muscle growth and promoting strength," says Cam Mitchell, the study's co-author and a doctoral candidate in kinesiology at McMaster's University in Ontario, Canada. 

The research suggests that the key to muscle gain is working to the point of fatigue and challenges the widely held belief that training with heavy weights is best for muscle growth, the Journal of Applied Physiology reports.

"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 and young male volunteers to measure how their leg muscles reacted to different forms of resistance training over a period of 10 weeks, according to a McMaster's statement.

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 programmes 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.