Muscle loss with aging is known as sarcopenia, a diagnostic term derived from two Latin words, "sarco" for muscle, and "penia" for wasting. It is a natural and progressive loss of muscle fiber associated with getting older.
At What Age Does It Happen?
An normal rate for muscle loss with aging has not been established. A 1998 article in the "Journal of Nutrition" reported on a cross section of research that showed the overall loss to be 35 to 40 percent between the ages of 20 and 80. Some research reports changes as early as your 20s, but most agree the most significant changes take place after age 50. Both genders lose the same percentage with aging but women lose less mass overall.
Is Aging Really the Reason?
Although more sedentary lifestyles as we age do play a role in the loss of muscle and accumulation of body fat, it is not due entirely to lifestyle. Active people lose muscle mass more slowly than their sedentary counterparts, but a comparison of active older athletes with younger athletes showed that the older athletes lost more muscle mass over time than their younger counterparts.
Do Some People Lose Muscle Earlier?
Although exercise helps everyone hold onto muscle mass longer, the biggest factor contributing to loss of muscle is that your ability to produce new muscle proteins seems to diminish as you age. A study reported in the "American Journal of Physiology" in 1998 found the ability to produce new muscle protein was reduced by 31 percent in middle age and 44 percent in older age.
Can You Delay Muscle Loss?
Because the mechanisms that control your ability to produce muscle proteins decreases with age, you will lose muscle over time. However, people who are active lose less than others the same age who are sedentary. Although you may not be able to set the clock back or keep the hands from turning, you can slow the rate of change with exercise.