Grandma and grandpa rarely win a weightlifting contest with their grandchildren. As people get old, they begin losing significant amounts of muscle mass, a deterioration scientists call sarcopenia (SN: 8/10/96, p. 90: http://www.sciencenews.org/sn_arch/8_10_96/bob1.htm). Even the muscle that remains in the elderly isn't usually as strong as it once was.
At last month's Integrative Biology of Exercise meeting in Portland, Maine, Dawn A. Lowe of the University of Minnesota in Minneapolis and her colleagues offered a clue to why aged muscle is weaker: In older muscle, a key protein, myosin, is shirking its job.
Muscle contraction is, in essence, molecular motion. Armies of myosin proteins simultaneously pull together countless filaments made of the protein actin. The head of the myosin protein mediates this contraction by changing from a state in which it weakly binds actin to one in which it holds firmly.
While comparing the muscles of young and elderly male rats, L