[Effect of weightlessness and hypokinesia on the velocity-strength properties of human muscles].

Before and after exposure to short- and long-term microgravity and prolonged bed rest velocity and strength parameters of leg muscles were measured by isokinetic dynamometry. It was found that long-term exposure to microgravity produced a more distinct decline of muscle strength than short-term exposure. At the same time prolonged bed rest led to greater strength losses than microgravity of comparable duration. After long-term flights individual variability of changes was twice as high as after prolonged bed rest. A comparable analysis of the above exposures demonstrated that the changes observed after long-duration exposures were associated with atrophic changes due to disuse while those seen after short-term effects were induced, as shown previously, by reflex tonic shifts related to support unloading.