Preliminary Investigation on Vertical Ankle Sway in Static Standing Under Eyes-Closed and Foam Pad Conditions

In human postural control, visual, proprioceptive, and vestibular senses work together to maintain balance. To assess individual sensory contributions, specific postural balance tasks have been designed. Previous research suggests that difficulty in appropriately switching between sensory inputs in response to environmental or physical changes may increase the risk of falls. Understanding an individual's sensory contributions may help them recognize situations where they are more likely to experience balance instability. Our research group has introduced a modified Sensory Organization Test (mSOT) as an optional assessment in comprehensive health check-ups conducted in collaboration with a hospital. This test aims to evaluate individual sensory contributions to balance control. This paper presents the results of 115 participants who underwent the test between late August and mid-December 2024. In particular, we focus on participants who exhibited pronounced vertical ankle sway during postural maintenance in the eyes-closed, double-leg stance condition on a foam pad. We confirmed the relationship between vertical ankle sway and COP and discuss the relationship between vertical ankle sway and sensory contributions.Clinical relevance-These findings provide foundational knowledge for developing sensory re-weighting assessment programs tailored to motor strategy in human posture control.