Aging protein saps muscle strength.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). 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 Portland is the largest city in the U.S. state of Maine, with a 2004 population of 63,882. Portland is Maine's cultural, social and economic capital. Tourists are drawn to Portland's historic Old Port district along Portland Harbor, which is at the mouth of the Fore River and part , Dawn A. Lowe of the University of Minnesota (body, education) University of Minnesota - The home of Gopher. http://umn.edu/. Address: Minneapolis, Minnesota, USA. in Minneapolis and her colleagues offered a clue to why aged muscle is weaker: In older muscle, a key protein, myosin myosin (mī`əsĭn), one of the two major protein constituents responsible for contraction of muscle. In muscle cells myosin is arranged in long filaments called thick filaments that lie parallel to the microfilaments of actin. , is shirking Shirking The tendency to do less work when the return is smaller. Owners may have more incentive to shirk if they issue equity as opposed to debt, because they retain less ownership interest in the company and therefore may receive a smaller return. its job. Muscle contraction Noun 1. muscle contraction - (physiology) a shortening or tensing of a part or organ (especially of a muscle or muscle fiber) contraction, muscular contraction shortening - act of decreasing in length; "the dress needs shortening" 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, Lowe and her colleagues observed that aged muscle had fewer myosin heads in the strong-binding state during a contraction. Young muscle fibers had about 30 percent of the myosin in that state, while the elderly muscle had only about 22 percent. This may partly explain why aged rat-muscle fibers exert only about 82 percent the force of young muscle. The next step, says Lowe, is to determine why myosin becomes less effective with age. |
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