Effect of a 4-week balance exercise with medio-lateral unstable sole on ankle joint functional ability.

[Purpose] This study examined the effects of 4-week of balance exercise with medio-lateral unstable sole on ankle muscle activation and functional ability. [Subjects and Methods] Thirty university students without current or past ankle injuries were assigned to either an experimental group or control group. The experimental group participated in a balance exercise program 3 times a week over 4 weeks, which consisted of one-leg stands and semi-squat exercises with medio-lateral unstable sole. The control group continued with their regular life activities without participation in the program. Electromyographic activities of peroneus longus and brevis muscles were recorded during stair descending immediately before and after the exercise program. Functional balance was tested with the Star Excursion Balance test immediately before and after the exercise program. Paired t-tests were used to assess statistical significance. [Results] Activation of peroneus longus and brevis and Star Excursion Balance Test scores in both groups did not show a significant difference between pre- and post-exercise. [Conclusion] A future study is suggested with increased level of medio-lateral perturbation during outcome measurements and exercises with addition of supervision in the exercise training and home program.