Strength and power training counteract loss of muscle mass

"There are basically two reasons that our muscle mass starts to shrink. The first is "sarcopenia" -- age-related muscle loss. This usually begins at around age 35 and occurs at a rate of 1 percent to 2 percent a year for the typical person. After age 60, it can accelerate to 3 percent a year. On average, adults who don't do regular strength training can expect to lose 4 to 6 pounds of muscle per decade.

The second reason our muscle mass starts to shrink is that, as we grow older, more of us use our muscles less. We don't spend as much time at sports as when we were younger. For most of us, our work doesn't require that we use our muscles much. Strength and power training can prevent, and even reverse, some of this loss."