Nishiumi Daichi, Hirose Norikazu
Graduate School of Sport Sciences, Waseda University, Saitama, Japan.
Faculty of Sport Sciences, Waseda University, Saitama, Japan.
J Hum Kinet. 2024 Sep 26;94:65-75. doi: 10.5114/jhk/190451. eCollection 2024 Oct.
This study aimed to investigate the acute effects of altering the braking rate of force development (B-RFD) and amortization force (Amf) during countermovement jumps (CMJs) on CMJ height. Nineteen healthy men and women with training experience participated, performing six CMJ variations at different velocities (preferred and fast) and depths (knee angles: 60°, 90°, and 120°). The measured variables included CMJ height, B-RFD, Amf, and impulses during the early and latter halves of the concentric phase (EI and LI, respectively). A two-way analysis of variance was employed, along with a correlational analysis of the rates of change for each variable. Significant velocity and depth effects were observed for B-RFD and Amf (p < 0.05). However, there was no significant velocity effect on CMJ height. No significant correlations were observed between the rates of change in B-RFD and Amf with CMJ height. Additionally, a high or a very high correlation (r ≥ 0.67) was observed between the rate of change in B-RFD and Amf with the rate of change in EI, while a moderate negative correlation (r = -0.43 to -0.53) was found between the rate of change in EI and LI. These findings suggest that improvements in B-RFD and Amf were associated with improvements in EI, while improvements in EI led to a reduction in LI, and consequently, improvements in B-RFD and Amf were not associated with an increase in CMJ height. In other words, improvements in B-RFD and Amf did not necessarily contribute to improvements in CMJ height.
本研究旨在探究在纵跳（CMJ）过程中改变力量发展制动率（B-RFD）和缓冲力（Amf）对CMJ高度的急性影响。19名有训练经验的健康男性和女性参与其中，以不同速度（偏好速度和快速）和深度（膝关节角度：60°、90°和120°）进行六种CMJ变式。测量变量包括CMJ高度、B-RFD、Amf以及向心阶段前半段和后半段的冲量（分别为EI和LI）。采用双向方差分析以及各变量变化率的相关性分析。观察到B-RFD和Amf存在显著的速度和深度效应（p < 0.05）。然而，CMJ高度没有显著的速度效应。未观察到B-RFD和Amf的变化率与CMJ高度之间存在显著相关性。此外，观察到B-RFD和Amf的变化率与EI的变化率之间存在高度或非常高度的相关性（r≥0.67），而EI和LI的变化率之间存在中度负相关性（r = -0.43至-0.53）。这些发现表明，B-RFD和Amf的改善与EI的改善相关，而EI的改善导致LI降低，因此，B-RFD和Amf的改善与CMJ高度的增加无关。换句话说，B-RFD和Amf的改善不一定有助于CMJ高度的提高。
