Abductor hallucis muscle activity during short foot exercise in combination with static and dynamic functional tasks

Abstract

Background: Short foot exercise (SFE) can be combined with dynamic functional tasks such as squats; however, it is unclear whether this combination increases intrinsic foot muscle activity. Research question: This study aimed to investigate and compare the abductor hallucis muscle (AbdH) activity during SFE in static and dynamic functional tasks. Methods: The AbdH electromyography data of 17 healthy participants with and without SFE were analyzed during static tasks (sitting, double-leg standing, and single-leg standing) and dynamic tasks (double-leg squat, single-leg squat, split squat, and heel-raise). The static tasks were performed with SFE for 5 seconds, and the dynamic tasks were performed while performing SFE. AbdH activity with or without SFE during the task was compared using the Friedman and Wilcoxon signed-rank tests. Results: AbdH activity was significantly greater in conditions with SFE than in those without SFE for all tasks (P < 0.01) except for heel-raise (P = 0.163). AbdH activity during SFE in single-leg standing was significantly higher than that in sitting, double-leg standing, and double-leg squats (P < 0.05). AbdH activity during SFE in the single-leg squat was also significantly greater than that in the sitting position (P = 0.024). No significant differences were found in any other between-task comparisons of AbdH activity during SFE. AbdH activity during tasks without SFE revealed significantly lower levels for sitting and double-leg standing compared to single-leg squat, split squat, and heel-raise (P < 0.001). Additionally, the activity in double-leg squat was significantly lower than in both single-leg squat and heel-raise (P < 0.05). Significance: Combining dynamic tasks, except for the heel-raise task, with SFE can increase AbdH activity more than dynamic tasks without SFE. However, clinicians should note that combining dynamic tasks with the SFE may not increase AbdH activity compared to combining static tasks with the SFE.