[Effect of 7-day immersion hypokinesia on the characteristics of precise movements]

Experiments were carried out to study the effect of 7-day immersion hypokinesia on precision movements that included reproduction of a certain isometric strain of leg muscles (30% from the maximum voluntary level) and angular displacement of the ankle (15 degrees) relative to the 90 degrees position. On the first postimmersion day the precision level deteriorated, i. e., the error and variability of the movements to be reproduced consistently increased. The precision decline was the highest with plantar flexion, when the error of the effort and position reproduction was 24 and 28%, respectively, and the lowest with dorsiflexion, when the error was 17 and 25%, respectively, versus 6-8% in the baseline tests. Precision disorders were seen in the structure of movements which lost their stereotypic pattern and became fragmentary, transforming into slow approximate movements versus the pattern of preimmersion movements that were of a rapid programmed control type. Precision changes during plantar flexion movements were usually excessive, hypermetric and almost twice longer than preimmersion. The origin of the above precision changes seems to be primarily associated with muscle atonia. At the same time data analysis shows that in nearly 50% of cases the values of precision changes in movements of various types (efforts and displacements) and different directions (plantar and dorsiflexion) were correlated. This is suggestive of common central mechanisms underlying their development.