Comparison of functional exercises on lower limb and trunk muscle activation in people with chronic ankle instability

Background/Aims: The aim of this research was to investigate muscle activation in the lower limbs and trunk during five functional exercises: forward lunge, rotational lunge, anterior direction one-legged standing exercise, posteriomedial direction one-legged standing exercise, and posteriolateral onelegged standing exercise in subjects with chronic ankle instability. Methods: Twenty-four subjects (10 males and 14 females) with chronic ankle instability participated in this study. Surface electromyography was used to measure the muscle activities of the peroneus longus, lateral head of the gastrocnemius, gluteus medius, and erector spinae. Normalised muscle activities are presented as percentage of MVIC (%MVIC). One-way repeated measures analysis of variance was used at a significance level of p<0.05. Findings: The peroneus longus and the lateral head of the gastrocnemius muscle activities significantly higher in anterior direction one-legged standing exercise than in the other exercises (forward lunge: p=0.005; rotational lunge: p=0.006; posteriomedial direction one-legged standing exercise: p=0.007; posteriolateral one-legged standing exercise: p=0.008; forward lunge, rotational lunge, posteriomedial direction one-legged standing exercise, posteriolateral one-legged standing exercise: p<0.001, respectively). The muscle activity of gluteus medius significantly lower in rotational lunge than in the other exercises (forward lunge: p=0.001, one-legged standing: p<0.001). Among the one-legged standing exercises, the muscle activity of the gluteus medius was lowest in the anterior direction onelegged standing exercise. The muscle activity of the erector spinae was significantly lower in the forward lunge and anterior direction one-legged standing exercise than in the other exercises (posteriomedial direction one-legged standing exercise and posteriolateral one-legged standing exercise: p<0.001). Conclusions: The anterior direction one-legged standing exercise, which activates the peroneus longus and the lateral head of the gastrocnemius muscle and reduces other muscles' activation proximally, would be an effective exercise to activate ankle muscles in the rehabilitation of people with chronic ankle instability.