Muscles and Body Fat

As people age, the amount of muscle tissue (muscle mass) and muscle strength tend to decrease. This process is called sarcopenia (which literally means loss of flesh). Loss of muscle mass begins around age 30 and continues throughout life. Muscle mass decreases because the number of muscle fibers decreases. This change may occur because the levels of growth hormone and testosterone, which stimulate muscle development, decrease with aging. Also, muscles cannot contract as quickly in old age.

Most older people retain enough muscle mass and strength to perform all necessary tasks. Many older people remain strong athletes. They compete in sports and enjoy vigorous physical activity. However, even the fittest may notice some decline as they age.

Regular exercise can partially overcome or at least significantly delay the loss of muscle mass and strength. With regular exercise, even people who have never exercised can increase muscle mass and strength. Conversely, physical inactivity, especially bed rest during an illness, can greatly worsen the loss. During periods of inactivity, older people lose muscle mass and strength much more quickly than younger people do. Thus, after 1 day of bed rest, older people may need about 2 weeks of progressively becoming more active to get back to the level of muscle strength they had before bed rest.

As people age, the amount of body fat tends to increase. Too much body fat can increase the risk of health problems. A healthy diet and exercise can help older people keep body fat from increasing too much.