Next spring, NIA plans to launch an 8-year study of how this muscle loss affects activity and recovery from disease in 3,000 otherwise healthy septuagenarians. At its annual meeting in October, the American Aging Association has scheduled a session on sarcopenia. And Miriam E. Nelson of the Tufts center has written a book for the general public, due out next year, describing exercises that her studies show can fight the ravages of muscle loss. Since he was 44, Forbes has measured his own fat-free mass on at least 150 separate occasions spanning 37 years. He has another 27 years' worth of data on a colleague, begun when that man was 53.
Skeletal muscle comprises about half of a person's lean body weight.
Those data, reported at the Experimental Biology '96 meeting in Washington, D.C., this past April, indicate that Forbes experienced a fairly constant 1 kilogram per decade loss of muscle, roughly twice the rate of his heavier, more muscular colleague. To get a speedier estimate of sarcopenia within the general population, Ronenn Roubenoff and Joseph Kehayias of the Tufts center have just finished measuring skeletal muscle in Boston area adults. By comparing people of different ages but similar builds, they're looking to identify when muscle loss begins and how quickly it proceeds. Though men tend to start with more muscle, they appear to lose about the same percentage as women over time. Moreover, there are some indications that sarcopenia's ravages accelerate with time.