The Relationship between Activity of Abductor Hallucis and Navicular Drop in the One-leg Standing Position

Abstract

[Purpose] This study examined whether abductor hallucis (AH) activity in the one-leg-standing position can be used to predict the navicular drop (ND) when it is or is not actively supporting the medial longitudinal arch. [Subjects] Forty healthy subjects without foot or ankle problems were recruited. [Methods] For all subjects, the ND was measured as the difference in navicular height between the subtalar joint resting (STJR) and subtalar joint neutral (STJN) positions while standing. AH activity was measured in both positions during one-leg standing. [Results] AH muscle activity in the STJR position was significantly negatively correlated with the ND, while AH muscle activity in the STJN position was not. Using a simple regression model, AH activity predicted the ND based on the STJR position. [Conclusion] The results suggest that AH activity is a good predictor of the ND. Therefore, intervention that activates the AH in the one-leg standing position could be used to correct the ND.