Abstract: Previous studies have demonstrated that balance function declines following short-term spaceflights (5–12 days), with performance influenced by prior flight experience [1]. The objective of this study was to assess these effects after long-term spaceflights (SFs). Thirty-two cosmonauts participated in the study, with an average SF duration of 165 ± 30 days. Tests were conducted pre-flight and on the 3rd (R+3), 7th (R+7), and 10th (R+10) days post-landing. The sensorimotor test protocol, as described by Wood et al. [2], was used to assess the interaction of visual, vestibular, and somatosensory inputs for maintaining upright stance. The Equilibrium Score, measuring maximum center of gravity fluctuations (range: 0–100), was calculated. Fifteen cosmonauts were first-time flyers (rookies), while 17 had previous SF experience (veterans). On R+3, no significant differences in EqScore between rookies and veterans were observed across all pos-tural tests. However, intra-group comparisons revealed variations in the depth and dynamics of recovery. In the test with unstable support and eyes open, postural stability significantly decreased after spaceflight in both groups (rookies: from 84.0 to 74.2; veterans: from 82.0 to 73.7). By R+10, rookies still exhibited reduced stability, while veterans showed recovery by R+7, with no significant differences from pre-flight values. In the test with unstable support, eyes closed, and head movements, both groups showed a signifi-cant post-flight decrease (rookies: from 50.9 to 31.4; veterans: from 48.0 to 37.1). However, rookies con-tinued to show reduced stability up to R+7, whereas veterans recovered more quickly. These tests assess the ability to use vestibular information effectively for balance control. The findings suggest that prior experience with prolonged spaceflight may facilitate faster recovery of so-matosensory integration for maintaining postural equilibrium.

Cite: Sayenko D.G. , Shishkin N.V. , Kitov V.V. , Shigueva T.A. , Tomilovskaya E.S.
CHANGES IN BALANCE FUNCTION FOLLOWING FIRST-TIME AND REPEATED LONG-TERM SPACEFLIGHT
NASA Human Research Program Investigators 28-31 Jan 2025