Extended bed rest ? often necessary during hospitalization ? leads to a substantial amount of muscle deterioration in older adults, researchers at the University of Arkansas for Medical Sciences (UAMS) report in the April 25 issue of the Journal of the American Medical Association.
The rate of muscle loss in 12 adults with an average age of 67 over 10 days was more remarkable and in a shorter period than a previous study of younger adults, said the research team led by William J. Evans, Ph.D., director of the Nutrition, Metabolism and Exercise Laboratory in the Donald W. Reynolds Institute on Aging at UAMS.
The researchers attributed the increased muscle tissue loss to inactivity that results in a large decrease in the ability of muscle cells to make new protein, the primary constituent of muscle.
Evans said the study, ?The Effect of 10 Days of Bed Rest on Skeletal Muscle in Healthy Older Adults,? demonstrated the ?best case scenario,? as the subjects were healthy with no functional limitations. Older patients hospitalized with disease or trauma could also face other factors such as inflammation and decreased food intake that could contribute to further loss of muscle tissue and function, he said.
?We found a dramatic reduction in muscle protein synthesis brought on by inactivity that caused the muscle loss,? said Evans, the Jane and Ed Warmack Chair in Nutritional Longevity Nutrition, Metabolism, a professor in the UAMS College of Medicine and a research scientist for the Central Arkansas Veterans Healthcare System. ?This is a striking loss of muscle in healthy individuals. When you consider the chronically ill facing longer hospitalizations or bed rest, the magnitude of muscle loss is extraordinary and should be treated.?
Evans said continued research by the team will examine different strategies for preventing muscle loss. Those potential treatments included nutritional supplements, exercise and the use of insulin sensitizers to prevent the reduction in muscle protein synthesis.
The muscle loss study appeared in a research letter published in the journal and is available online at http://jama.ama-assn.org/. The Journal of the American Medical Association, published continuously since 1883, is the most widely circulated medical journal in the world.