SUNDAY, May 13 (HealthDay News) -- Doing more repetitions with less weight builds muscle and increases strength just as effectively as training with heavy weights, a new Canadian study indicates.

The critical factor in muscle gain is pushing yourself to the point of fatigue, according to the researchers at McMaster University in Hamilton, Ontario.

They examined how different combinations of weight loads and repetitions affected the leg muscles of young men. The participants trained three times a week for 10 weeks doing one of three resistance training regimens: one set at 80 percent of maximum load; three sets at 80 percent of maximum load; or three sets at 30 percent of maximum load.

A set consisted of doing as many repetitions as possible with the assigned loads -- typically eight to 12 times a set at the heaviest weights and 25 to 30 times a set at the lowest weights.

"We found that loads that were quite heavy and comparatively light were equally effective at inducing muscle growth and promoting strength," Cam Mitchell, a lead study author and a Ph.D. candidate in McMaster's kinesiology department, said in a university news release.

The findings, recently published online in the Journal of Applied Physiology, challenge the widely held belief that using heavy weights is the best way to promote muscle growth and boost strength.

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

More information

The U.S. Centers for Disease Control and Prevention has more about strength training for older adults.