In the wake of a 100 year old marathoner , Dr. Mirkin gives us insight into Sarcopenia, or muscle loss with aging. Reprinted with permission from Dr. Mirkin's newsletter. To learn about Dr. Mirkin and read more health articles, visit drmirkin.com. Dr. Gabe Mirkin's Fitness and Health E-Zine November 13, 2011 Sarcopenia: Muscle Loss with Aging Competitive masters athletes, 40 to 81 years old, who trained four to five times per week did not lose any muscle size or significant strength with aging (The Physician and Sportsmedicine, October 2011;39(3):172-8). This shows that loss of muscle size and strength in older people is caused by lack of exercise, not just with aging. The athletes did gain fat in spite of exercising. Those in their 70s had almost as much strength and thigh muscle size as those in their 40s. MOST PEOPLE LOSE MUSCLE: Recent studies show that after age 40, men lose more than eight percent of their muscle size each decade, and this loss of muscle increases after age 70. The people who lose the most muscle are usually the ones who die earliest. They are also most at risk for falls and broken bones. HOW EXERCISE PREVENTS MUSCLE LOSS WITH AGING: Muscles are made up of thousands of individual muscle fibers. Each muscle fiber is innervated by a single nerve. With aging, humans lose the nerves that innervate muscle fibers, and with each nerve loss, they lose the associated muscle fiber so muscles become smaller. We used to think this happens because of aging. However, this new study and others show that lifelong competitive athletes do not lose the nerves that innervate their muscles with aging. They retain the nerves and therefore retain most of the muscle fibers that they would have lost if they were inactive. MESSAGE: If you exercise regularly, continue to do so. If you don't, check with your doctor and then get instructions on how to start an exercise program.