If you want to lose weight, build strength, and boost your metabolism, experts advise that pumping iron is your best bet. But if the idea of heavy lifting -- with all that grunting -- intimidates you, a new study reveals that lighter weights and more repetitions are equally effective, as long as you work your muscles 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 researcher Cameron Mitchell at McMaster University in Hamilton, Ontario, Canada in a statement released Monday.
According to the release, the study "challenges the widely accepted dogma" that to achieve optimal muscle growth, you'll need to lift heavy weights, with repetitions anywhere from six to 12 times before fatigue. Of course, the downside of lifting lighter weights is that you'll need to perform about twice as many reps to achieve the same effect.
To reach their findings, researchers conducted a series of tests on healthy, young male subjects to measure how their leg muscles reacted to different forms of resistance training. The subjects worked out over a period of 10 weeks, three times a week.
For the group lifting heavy weights, subjects performed three sets of eight to 12 repetitions; for the group lifting lighter weights, they performed three sets of 25 to 30 repetitions. After 10 weeks, both heavy and light groups saw significant gains in muscle volume -- as measured by MRI -- "with no difference among the groups," stated the release.
The findings could be particularly encouraging to older adults with joint problems, who want the benefits of weight training but without the risks of overdoing it. "This study shows that they have the option of training with lighter and less intimidating loads and can still receive the benefits," adds Mitchell. Recent research also reveals that seniors over 60 need to lift weights more often than young people to maintain their muscle mass.
The study is published online in the Journal of Applied Physiology.