ИСТИНА

Alterations in motor system structure and function are the constant consequences of exposure to weightlessness of different duration (Kozlovskaya et al., 1987). The studies performed after space flights (SF) and in onground models have shown that microgravity influences on all the segments of motor system – from structure of muscle fibers to coordination of complex voluntary movements (Shenkman et al., 2000; Grigoriev et al., 2004). In particular, it was shown that there were alterations of gait biomechanics as well as changes of EMG activities in muscles participating in locomotor acts. The current presentation is dedicated to the role of space flight factors in locomotor system's activity. Physiological characteristics of locomotions have been studied in the course of long term SF and after its accomplishment. Our studies revealed the different strategies of treadmill walking and running in weightlessness, which was demonstrated by redistribution of support reactions registered from the special soles. On Earth support loading is equally distributed between heel and tarsal areas of the soles; at the initial months of SF the main load is registered in tarsal areas. Further the tendency to spread of support loading to the heel zones is observed. Apparently this reflects the processes of motor learning to perform locomotions under the new environment conditions. It is necessary to note that the values of support reactions at the same speed of running are much lower in SF. At the same time EMG activity of shin and hip muscles during execution of locomotor acts undergo significant changes in the course of SF: amplitudes and duration of EMG bursts are increased, the involvement of m. soleus in walking is decreased. Recovery of mentioned parameters after space flight takes more than 10 days: on the 12th day after landing some of the parameters were still changed. The study is supported by RFBR project No 16-29-08320.