The older you become, the more you need to exercise. Researchers at Slippery Rock University of Pennsylvania measured grip strength in older men at baseline and an average of seven years later (Aging Male, September-December 2005). The men squeezed a machine that measured the force that they could exert. They lost 20 percent of their grip strength in seven years. The older they were, the more they lost. Those who lost the most height or weight, those on calcium channel blockers for high blood pressure, and those who took in the most caffeine had greater losses of strength. Loss of height is linked to osteoporosis, which is associated with loss of muscle. High blood pressure and unintentional weight loss indicate other health problems. No explanation was offered for the association of caffeine with loss of muscle strength.

These results are expected. Muscles are made of millions of individual muscle fibers. A single nerve enervates each fiber. With aging, a person loses nerve fibers that cause loss of each connected muscle fiber. However, you can continue to build strength in the remaining muscle fibers into your 90's and beyond. Perhaps all people over 50 should get a stress electrocardiogram as a screening test to see if exercise is likely to harm them. If they pass the test, they should start or continue an exercise program that includes some form of strength training such as lifting weights or using strength-training machines.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in four specialties, including sports medicine. Read or listen to hundreds of his fitness and health reports at http://www.DrMirkin.com

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