Most health experts these days are counseling older people to lift weights to maintain their muscular strength and energy. Given that most of us thought that weight lifting was for Bulgarian men and teenage boys, it is hard to know what to do and how. Today weights are sold in sporting goods stores, and it is possible to get weights that weigh one pound or 50. Most people might think that they should take the heaviest weights that they can lift, but this is not necessarily so, and that is good news for most of us. A recent study done at McMaster University in Canada found that it is not the amount of weight lifted that matters for building larger muscles, but the muscular fatigue that occurs. Growing bigger muscles means stimulating them to produce more muscle fiber. The bad news is that you must exercise until you can’t do another repetition; that is what builds muscle. Overall, people who used lighter weights gained more muscle mass than those who used heavier ones.
From: Secrets to Pumping Iron by Dr. Mitchell Hecht. Philadelphia Inquirer, August 30, 2010, E2