Purpose: This study aimed to develop a more effective exercise program for lower extremity muscle function by evaluating the effects of an 8-week lunge exercise performed on an unstable support surface on lower extremity muscle function, body composition, and body balance in middle-aged women.

Methods: Twenty participants were divided into two groups (control group: exercise on a stable support surface, n=10; experimental group: exercise on an unsta ble support surface, n=10). Each participant performed the exercise program for 8 weeks (three sessions a week, 50 min/session).

Results: The results revealed that body fat percentage decreased significantly in the experimental group (p<0.01). Additionally, lower-extremity muscle mass and function increased significantly in both groups (p<0.05), but with no significant difference between the groups. Moreover, the results of the static and dynamic balance tests indicated that balance improved in both groups, with significantly greater improvements in the experimental group than in the control group (p<0.05).

Conclusion: Lunge exercise on stable and unstable support surfaces improves muscle function and static balance in middle-aged women. In particular, lunge exercise on an unstable support surface was more effective at reducing body fat than lunge exercise on a stable support surface and was also found to improve dynamic balance. Therefore, a program consisting of lunge exercises on an unstable support surface may be suitable for body improvements in middle-aged women.