Effect of Foot Position on Ankle Muscle Activity During Wobble Board Training in Individuals With Chronic Ankle Instability.

Objective: The purpose of this study was to compare the effects of foot positioning on muscle activities of the peroneus longus (PL), medial gastrocnemius (MG), and tibialis anterior (TA)/PL ratio in individuals with chronic ankle instabilities (CAI) during wobble board training.

Methods: Thirty individuals with CAI were included, and statistical significance of PL and MG muscle activities was determined using 1-way repeated measures analysis of variance alongside TA/PL activity ratio at the university research laboratory. The participants performed the wobble board training in 3 different foot positions: medial from the centerline of the wobble board (WBT-M), middle from the centerline of the wobble board, and lateral from the centerline of the wobble board (WBT-L). Peroneus longus, MG, and TA muscle activities were measured using surface electromyography.

Results: Peroneus longus activity was significantly higher in the WBT-L position than in the other 2 positions, and it was significantly higher in the middle from the centerline of the wobble board than in the WBT-M position. Medial gastrocnemius activity was significantly greater in the WBT-L position than in the other 2 positions. Tibialis anterior/PL ratio was higher in the WBT-M position than in the other 2 positions.

Conclusion: The findings of this study showed that WBT-L increased PL muscle activity by >70% of the maximal voluntary isometric contraction without increasing TA/PL ratio in individuals with CAI.