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May 30, 2007Aerobic Exercise Helps Maintain Muscle in Elderly |
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From EurekAlert! - Breaking News: Why do older people tend to lose muscle mass and grow frail? One important factor identified by medical science is the reduced ability of the elderly to respond to the muscle-building stimulus of the hormone insulin. Insulin is best known for its link to diabetes --- a condition in which either a complete lack of insulin or systemic resistance to the hormone's activity (as in type 2 diabetes) causes blood sugar levels to soar out of control. Recent studies have shown, however, that insulin also provides crucial assistance in building muscle, and that its ability to do so drops off dramatically in the elderly. Now, a small but provocative study by medical researchers in Texas and California suggests that a simple, cost-free therapy appears to largely overcome that drop-off in insulin response: moderate aerobic exercise such as walking. Experiments at the University of Texas Medical Branch at Galveston (UTMB) and the University of Southern California, Los Angeles conducted on 13 healthy volunteers in their late 60s showed that 45 minutes of walking 20 hours before exposure to insulin restored the muscle-growth-stimulating effects of the hormone to levels comparable to those seen in normal young adults. Prior research had suggested that a large part of the problem older people experience lies in the tiny blood vessels that feed the muscles protein-building amino acids, glucose and insulin (which itself also works within muscle cells as a powerful protein growth factor). These revealed that the volunteers who exercised had both higher blood flow and net muscle protein growth. In addition, the researchers screened the muscle biopsy samples for signals associated with insulin's ability to stimulate the assembly of muscle protein from amino acids.
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