Acute effects of whole-body vibration combined with blood flow restriction on electromyography, blood lactate level and jumping performance in female volleyball players
Abstract:
This study aimed to examine and compare the acute effects of whole-body vibration (WBV), blood flow restriction (BFR), and its combination (WBV+BFR) on electromyography, blood lactate level, and jumping performance in female volleyball players. Twelve university female volleyball players, aged between 18-25 years, participated in this study. Each subject performed a dynamic squatting exercise under 4 different conditions, namely control (CON), whole-body vibration (WBV), blood flow restriction (BFR), and combined whole-body vibration and blood flow restriction (WBV+BFR), in a randomized counterbalanced design. Electromyography (EMG) and jumping performance test included countermovement jump (CMJ) and squat jump (SJ), were recorded before and after the experiment in each condition. Two-way ANOVA was applied for data analysis with a statistical significant at p-value < .05. The results showed that there were no significant differences in all variables examined in CON condition before and after intervention. However, WBV resulted in significant increases (p < 0.05) in rate of force development during take-off phase, leg stiffness, as well as the amplitude of EMG from medial gastrocnemius for CMJ. In addition, jump height and flight time were significantly increases (p < 0.05) for SJ while no significant differences were found in absolute and relative peak power in both jumping test. BFR elicited significant increases (p < 0.05) in absolute and relative peak power for CMJ and SJ, although the leg stiffness was significant decreased (p < 0.05) for SJ. WBV+BFR resulted in significant increases (p < 0.05) in both absolute and relative peak power for CMJ and SJ. In addition, while the rate of force development during take-off phase and EMG activity from gastrocnemius showed significant decreases (p < 0.05) for CMJ, the reactive strength, leg stiffness and EMG activity of rectus femoris were significant increased (p < 0.05) for SJ. There were no significant main effects of condition, of time, and an interaction of condition x time on all variables for CMJ. However, there was a significant main effect of condition (BFR vs WBV+BFR) on leg stiffness for SJ and a significant main effect of time (p < 0.05) on blood lactate level for all conditions. In conclusion, these findings demonstrated that both whole-body vibration and its combination with blood flow restriction were effective in enhancing muscular power, with greater improvements observed in the latter, although they appeared to have no effect on jumping performance in female volleyball players.