| Abstract: | Gastrocnemius muscle biopsies of 10 healthy volunteers, aged 27 to 44 years, who were exposed to head-down tilt (-8 degrees) for 370 days, were examined. The test subjects were subdivided into two equal groups that were assigned exercises of different type and workload. This prolonged bed rest caused atrophic changes in skeletal myofibers and decrease of their metabolic rate. Regular exercise produced a beneficial effect on the myofibers and reversed hypokinesia-induced changes but partially. The efficacy of the countermeasures depended, to a certain extent, on the time, when they were initiated, and the intensity, with which they were performed: the efficacy was higher and atrophic changes were delayed, if the subjects began exercising earlier and did it more actively. |
