Influence of exercise or nutrition countermeasures during 60 d of bedrest in women: Thigh and calf muscle volume

Abstract

Twenty-four women underwent 60 d of bedrest (BR, n=8) to examine the effect of a concurrent aerobic (27 sessions) and resistance (19 sessions) exercise (BRE, n=8) or a leucine enriched high protein nutrition (BRN, n=8) countermeasure. Magnetic resonance imaging was completed before and on days 29 and 57 of bedrest. BR had a −21±1% loss (P<0.05) of thigh muscle volume on day 57. The combination of aerobic and resistance exercise (BRE) was successful in maintaining thigh muscle volume (P>0.05), while nutrition (BRN) exacerbated this loss (−24±2%, P<0.05) compared to BR. BR had a −29±1% loss of calf muscle volume on day 57. The combination of aerobic and resistance exercise (BRE) provided a large but not complete offset of calf muscle volume loss (−8±2%, P<0.05). BRN had a −28±1% loss of calf muscle volume (P<0.05), which was no different than BR (P>0.05). The nutrition countermeasure was not effective in offsetting muscle mass loss during bed rest. The concurrent aerobic and resistance exercise protocol was an effective countermeasure to prevent thigh muscle loss. While the exercise protocol offset 21% of the calf muscle volume loss, modification of this regimen is needed to be completely effective in women. Sponsors: NASA, ESA, CNES