Bed rest, then rehab

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Science Translational Medicine  12 Aug 2015:
Vol. 7, Issue 300, pp. 300ec138
DOI: 10.1126/scitranslmed.aad0226

Muscle wasting is a hallmark of human aging. Although aging is inescapable, there is tremendous opportunity to forestall disease and disability associated with muscle atrophy. Tanner and colleagues provide new insights into accelerated muscle wasting with age by investigating how aging alters the body’s response to bed rest. The investigators recruited 14 young (18 to 35 years) and 9 older (60 to 75 years) individuals to participate in a study where muscle mass, strength, and protein metabolism were evaluated before and after 5 days of bed rest. Leg strength and lean mass decreased significantly in older adults over this short time period, whereas the changes in young adults were minimal. Muscle biopsies showed that muscle protein synthesis after a meal (nutritional stimulus) was blunted in old but not in young adults. Furthermore, several markers of protein degradation were higher in older adults during bed rest, making them more susceptible to muscle loss. In light of these findings, the detrimental effects of repeated hospitalizations on muscle mass in older adults are clear. Fortunately, the authors showed that high-intensity exercise in the 8 weeks following bed rest could restore lean muscle mass, strength, and protein metabolism in older adults, indicating that exercise is an effective strategy to keep older patients healthy.

R. E. Tanner et al., Age-related differences in lean mass, protein synthesis and skeletal muscle markers of proteolysis after bed rest and exercise rehabilitation. J. Physiol. 10.1113/JP270699 (2015). [Abstract]

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