| Abstrakt: |
Purpose: Whole-body vibration (WBV) has been reported to influence performance improvement. However, its effects may vary based on device parameters and body positioning. This study aims to assess the effects of two frequencies and two positions on jump kinetic variables. Methods: Thirty-four healthy non-athlete females underwent four WBV protocols involving different combinations of medium (30 Hz) and high (50 Hz) frequencies, as well as static and dynamic squat positions. Participants performed three counter-movement drop jumps before, 1 min, and 10 min after each protocol. Jump variables were extracted using acceleration data from an inertial measurement unit attached to participants' waists. Results: Three-way repeated measure ANOVA results revealed a significant position effect on maximum contact power (p = 0.046) and a significant time effect on maximum contact force (p = 0.010), concentric contact impulse (p < 0.001), jump height (p = 0.014), and the reactive strength index (p = 0.007). Bonferroni analysis showed an increase in maximum contact power in the dynamic squat protocols. However, there was a decrease in maximum contact force, jump height, and the reactive strength index, along with an increase in contact impulse in the concentric phase for all frequencies and squat positions. Conclusion: While dynamic squatting increased maximum power during the concentric phase, highlighting the importance of dynamic contractions during vibration, temporary declines in other key jump variables suggest that acute WBV effects in non-athlete subjects might negatively impact overall function. Caution is advised when considering the immediate effects of WBV in this group. [ABSTRACT FROM AUTHOR] |
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