Most of us lose muscle as we age—a loss of one to two percent a year after age 50, on average, or about 30 percent between age 50 and 70. In particular, arms and legs weaken and look thinner or flabbier. It becomes harder to lift packages. Loss of muscle in the legs increases the risk of falls. This steady loss of muscle mass and strength tends to accompany many of the things we associate with aging: becoming less active, eating less healthfully, developing chronic diseases, becoming frail.
When the muscle loss becomes relatively severe, it’s called sarcopenia. (Similarly, when age-related bone loss goes beyond a certain point it’s called osteopenia and then, if it gets worse, osteoporosis.) But sarcopenia isn’t inevitable.
Muscle: use it or lose it
There’s no standard way to define or diagnose sarcopenia, since age-related muscle loss occurs over a continuum (as does bone loss). It isn’t just a matter of measuring loss of muscle size, but also of evaluating changes in muscle quality and functional abilities. Thus, there are varying estimates about how many people have sarcopenia— anywhere from 10 to 50 percent of those over age 70.
Many factors besides age-related lifestyle changes contribute to sarcopenia. Metabolic changes result in more protein breakdown in muscles and reduced muscle synthesis. Declining hormone levels also come into play, as do pro-inflammatory compounds and cell-damaging free radicals, which can promote muscle wasting and affect muscle fibers. Rapid weight loss (from dieting or illness) as well as prolonged bed rest can accelerate muscle loss.
Pump it up: never too late
Countless studies have shown that older people who do resistance training can significantly improve their muscle strength and performance, even after just a couple of months of training—and even if they are frail and over age 80. Any strength training can help prevent or treat sarcopenia. Strenuous workouts are most effective, according to a 2010 analysis in Aging Research Reviews, which included data from 47 studies, though that would be challenging for many sedentary older people.
Most Americans—even vegetarians and athletes—get more than enough protein from food. Older people are often exceptions, however. Sometimes it’s because they simply eat less or have trouble chewing protein sources such as meat.
The recommended dietary allowance (RDA) for adults is 0.8 grams of protein a day for each kilogram (2.2 pounds) of body weight. That’s 56 grams of protein for someone weighing 154 pounds.
It’s estimated that 40 percent of people over 70 don’t consume that much protein. And some researchers believe that older people should aim higher—at least 1.3 grams per kilogram, or 91 grams of protein for a 154-pounder.