Sex difference on spatial-temporal gait characteristics during walking with supra-threshold plantar vibration: implications for future space missions

This study aimed to inquire how sex difference affected gait characteristics of different sexes when walking with supra-threshold plantar vibration.

A total of thirty-eight healthy young adults (twenty males and eighteen females) participated in this study. Each participant was instructed to walk at their preferred walking speed with supra-threshold plantar vibration (130% of individual vibrotactile threshold) or without plantar vibration for two 3-minute trials. A motion capture system with eight infra-red cameras was used to capture the three-dimensional spatial location of 12 retro-reflective markers and measure spatial-temporal gait characteristics. Dependent variables included standardized step length, standardized step width, standardized heel elevation, step time, and respective variabilities (coefficients of variation).

Significant interaction between sex effects and effects of supra-threshold plantar vibration was observed in standardized step width (F_1,36=4.405, p=0.016), standardized heel elevation (F_1,36=7.754, p=0.008), and all gait variabilities (standardized step length variability (F_1,36=5.731, p=0.022), step width variability (F_1,36=13.113, p=0.001), heel elevation variability (F_1,36=11.695, p=0.002), and step time variability (F_1,36=8.266, p=0.007)). Post-hoc comparisons revealed that males demonstrated significantly lower standardized step width (p=0.019 and 0.032), standardized step length variability (p=0.015 and 0.001), standardized heel elevation variability (ps0.001), and step time variability (ps0.001) than females while walking with/without supra-threshold plantar vibration. However, standardized heel elevation (p=0.025 and 0.040) and standardized step width variability (p=0.011) were significantly higher in males.

Our results inferred two-folded meanings: (1) supra-threshold plantar vibration provided greater perturbation on gait performance of females, manifesting as wider but lower steps with greater variabilities; (2) gait variability might be a better indicator than spatial-temporal gait characteristics to investigate the sex effect in gait analysis.

To our knowledge, the current study was the first one to investigate the effect of sex difference on spatial-temporal gait characteristics and gait variabilities when walking with supra-threshold plantar vibration. Our results revealed that females adopted a conservative gait strategy to compensate for the somatosensory perturbation, indicating that females relied more on somatosensory feedback than males during walking. Moreover, supra-threshold plantar vibration is an appropriate tool to simulate the lack of somatosensory feedback in future sensorimotor training for space missions.