Indicators of cosmonaut locomotor functions stability: A new method for ground-reaction forces analysis.

The paper introduces a new method for ground-reaction forces (GRF) analysis for the evaluation of cosmonaut locomotor functions stability after a long-duration spaceflight (LDSF). The method is based on the analysis of GRF profiles obtained before and after LDSF by standard БД-2 treadmill reaction force data readings. Following probabilistic indicators were introduced: distributions of step and step-phase duration probabilities, their extremums, standard deviations and inverse coefficients of variety; step structure variability; the non-stationarity index for step durations arrays; GRF pattern, its width and maximum. Every indicator of one cosmonaut pilot study has changed drastically after LDSF. The new statistics provided appeared to be promising indicators of locomotor function state. A further trial of the new method may provide new knowledge of human movement strategies alterations after LDSF and may establish it as a standard analytical procedure for personalized flight assistance after its reliability verification. • New standard tests are needed for cosmonaut locomotor function evaluation. • The new GRF analysis method for standard ISS equipment was introduced. • The new GRF analysis showed drastic changes in one cosmonaut parameters. • Step duration stability, step pattern, IVC and others changed after spaceflight. • The new indicators are promising but more test subjects are needed. [ABSTRACT FROM AUTHOR]