Fixed foot balance training increases rectus femoris activation during landing and jump height in recreationally active women.

The objective of this study was to determine the effects of fixed foot and functionally directed balance training on static balance time, muscle activation during landing, vertical jump height and sprint time. Twenty-four recreationally active females were tested pre- and post-training (fixed foot balance training, n= 11, functionally directed balance training, n = 7 and control group, n = 6). Experimental subjects completed either fixed foot or functionally directed balance exercises 4 times/week for 6 weeks. Surface electromyography (EMG) was used to assess preparatory and reactive muscle activity of the rectus femoris (RF), biceps femoris (BF), and the soleus during one- and two-foot landings following a jump. Maximum vertical jump height, static balance and 20-meter sprint times were also examined. The fixed foot balance-training group showed a 33% improvement (p < 0.05) in static balance time and 9% improvement in jump height. Neither type of training improved sprint times. Further analysis revealed significant (p < 0.05) overall (data collapsed over groups and legs) increases in reactive RF activity when landing. Independently, the fixed foot balance group showed a 33% increase in reactive RF activity (p < 0.01). Overall, there was also significantly less reactive co-activation following training (p < 0.05). It appears that fixed foot balance training for recreationally active women may provide greater RF activity when landing and increased countermovement jump height. Key pointsBalance training increased rectus femoris EMG activity upon landing from a stride.Fixed foot balance training improved countermovement jump height.Neither fixed foot nor functionally directed balance training elicited changes in sprint times.