Effects of Ankle Eversion, Limb Laterality, and Ankle Stabilizers on Transient Postural Stability During Unipedal Standing

Abstract

Transient postural stability (TPS) is an individual’s ability to keep postural balance for a short duration. It is particularly useful for evaluating the danger situation faced by persons. This study examines the effects of an inclined surface on TPS during unipedal standing with ankle eversion. Ten male and nine female healthy adults were requested to unipedally stand with dominant and non-dominant leg respectively on a platform. The platform was manually regulated to three inclination angles (0°, 10°, and 20°) for the subjects to stand with ankle eversion. Three ankle stabilizer conditions were investigated, namely barefoot control, elastic ankle tape, and a semi-rigid brace. The plantar pressure distributions were measured and analyzed for 18 conditions (two laterals, three ankle inversions, and three stabilizers) for each subject. The anterior/posterior (A/P-FR) and medial/lateral force rates were used to evaluate TPS in two directions, respectively. The results show that the A/P-FR was significantly higher for the non-dominant side compared with that for the dominant side when subjects stood with ankle eversion, indicating that the anterior/posterior TPS of the non-dominant foot is higher. Ankle eversion mainly destroys the medial/lateral TPS during unipedal standing with the dominant foot. Compared with the semi-rigid ankle brace, the elastic tape was more helpful in maintaining medial/lateral TPS during unipedal standing with ankle eversion.