[Purpose] The purpose of this study was to analyze the effect of isotonic, isokinetic and isometric exercise on the muscle activity and the balance of ankle joint. [Methods] The subjects of this study were 30 healthy adults (man=15, woman=15) in their 20s and were divided into three groups (isotonic=10, isokinetic=10, isometric=10). Non-dominant leg was performed exercises after leg dominance was based on the preferred kicking leg. Maximal voluntary isometric contraction was performed before exercise protocol. The isotonic exercise group was performed 3 sets of 50% MVIC 10 contractions. The isokinetic exercise group was performed 3 sets of 60°/sec 10 contractions. The isotonic exercise group was performed 3 sets of 3 repetitions 100% MVIC plantarflexion and 70% MVIC dorsiflexion of 15s contractions 5s rests. The rest time was 1 min between sets avoid to fatigue effect. The muscle activities of tibialis anterior(TA), medial gastrocnemius(GCM) and peroneus longus(PL) were measured by using the surface EMG. The balance was measured evaluated by using eyes open one-leg stand test. The EMG and balance was measured before and immediately after their exercises. Multivariate analysis of variance (MANOVA) was used to analyze the differences of the muscle activity and balance between three groups. [Results] The change in muscle activity between the pre-test and post-test for the three groups didn''t have the interaction effect between group and time and the main effect of time was not found in the groups. The main effect of the group was found in the non-dominant TA, the non-dominant GCM, the non-dominant PL, the dominant GCM and the dominant PL. The change in balance between pre-test and post-test for the three groups didn''t have the interaction effect between group and time. The main effect of group did not find in the groups. The main effect of time was found in the groups when the sway area was measured during the time it was supporting the non-dominant side and the dominant side. [Conclusion] This study would be of help in the future, in selecting the type of exercise according to the planned purpose because it was shown in this study that the muscle activity and balance might vary according to the type of exercise.

Key words: isotonic, isokinetic, isometric exercise, muscle activity, balance