Jump Tests after Support Unloading of Various Durations: Maximum Height and Accuracy of Performance

This paper presents the results of a study of changes in speed–strength parameters of the musculoskeletal system of the human lower extremities and accuracy factors in performing multi-joint movements after exposure to models of physiological effects of microgravity such as 21-day head-down bed rest (HDBR) and 7-day dry immersion (DI) with electro-myostimulation (EMS) as a preventive measure against muscle atony. Maximum jump height, as well as the accuracy and variability of the jump height to a predetermined height, were studied. The results of the study have shown that the exposure to microgravity models has a similar effect on the absolute speed–strength parameters of lower extremity muscles and leads to their decrease. At the same time, HDBR and DI have different effects on the accuracy of performing multi-joint movements to a predetermined height. Thus, the accuracy increased after HDBR, while it decreased or remained at the background level after DI. The decrease in the accuracy after DI may result from the use of EMS during DI.