CHANGES IN VOLUME, MUSCLE COMPARTMENT, AND COMPLIANCE OF THE LOWER-EXTREMITIES IN MAN FOLLOWING 30 DAYS OF EXPOSURE TO SIMULATED MICROGRAVITY

  • 1 July 1989
    • journal article
    • research article
    • Vol. 60  (7) , 653-658
Abstract
The purpose of these experiments was to test the hypothesis that reduced size of the leg muscle compartment following exposure to long-duration microgravity would be associated with increased leg compliance. Eight men, 31-45 years of age, were measured for vascular compliance of the calf and serial circumferences of the thigh and calf before, during and after 30 d of continuous 6o head-down bedrest. Cross-sectional areas (CSA) of muscle, fat, and bone compartments in the thigh and calf were determined pre- and post-bedrest by computed tomography. Calculated leg volumes decreased (p < 0.05) in the calf by 9.9% and in the thigh by 4.5% from pre- to post-bedrest. Muscle compartment CSA also decreased (p < 0.05) in both calf (-4.8%) and thigh (-8.1%); leg compliance (vol%/mm HG .times. 100) increased (p < 0.05) from 3.9 .+-. 0.7.+-. 4.9 .+-. 0.5. Calf compliance measured before and after bedrest was inversely related to calf muscle compartment CSA (r =-0.61, p < 0.05) and the percent decrease in calf muscle compartment CSA from pre- to post-bedrest was inversely correlated with an increase in calf compliance (r = -0.72, p < 0.05). Increased leg compliance following long-duration spaceflight is associated with reduced size of the leg muscle compartment.