Effects of Uneven Ground Surface on Human Balance

Abstract

The effect of anteroposteriorly slanted ground surface on human posture control at fully flexed trunk postures was investigated in this study. Custom made wooden apparatus were used to simulate slanted ground surfaces, the slanted were set at -15, 0 and 15 degrees respectively. The flat ground condition was included in the study as a control. Fourteen healthy male subjects were asked to maintain in fully flexed trunk posture while standing on different ground surfaces. The segmental sway motion of C7, T12 and S1 spinal vertebrae in the anteroposterior (AP) and mediolateral (ML) directions were recorded. Results showed that when standing on an anteroposteriorly slanted ground surface and facing downhill (i.e. -15 degree condition) subjects consistently demonstrated the highest sway speeds and reported the highest subjective rating of instability. Therefore, we concluded that, when standing on an anteroposteriorly slanted ground surface in a fully flexed trunk posture facing downhill may result in much higher risk of falling in comparison to facing the opposite direction.