Kennedy Rodney A, Drake David
School of Sport, Ulster University, Jordanstown, UK -
Ulster Rugby, Kingspan Stadium, Belfast, UK.
J Sports Med Phys Fitness. 2017 Oct;57(10):1261-1266. doi: 10.23736/S0022-4707.17.06848-7. Epub 2017 Jan 13.
A countermovement jump (CMJ) is routinely used in many sporting settings to provide a functional measure of neuromuscular fatigue. However, the variables that are most sensitive to fatigue remain somewhat unclear. The purpose of this study was to determine the acute changes in neuromuscular fatigue in rugby union players during a period of preseason training.
Nine male (age: 19.0±1.5 years) academy rugby union players performed five CMJ trials on three occasions, at baseline, 24 hours and 48 hours postbaseline. The fatiguing protocol consisted of multiple high-intensity training sessions commensurate with the period of preparation and the sport. A total of 14 CMJ variables were derived from the force-time curve. Meaningful differences in CMJ performance were examined using the magnitude of change (effect sizes; ES) compared to baseline.
Most variables, 9 of the 14, showed substantial decreases at 24 hours postbaseline. Mean concentric power, peak velocity, jump height and force at zero velocity were impaired by the greatest magnitude (ES=-0.98 to -1.57). At 48 hours postbaseline, substantial increases in eccentric duration, concentric duration and total duration were first observed (ES=0.48 to 0.61). Concomitantly, peak power, peak velocity and jump height, recovered to baseline levels.
During the late regeneration phase, neuromuscular fatigue can manifest itself as an altered movement strategy, rather than as a simple reduction in physical output such as jump height. Practitioners are therefore advised to incorporate a wide range of variables when trying to identify subtle changes in the bimodal recovery pattern associated with stretch-shortening cycle induced fatigue.
反向纵跳（CMJ）在许多体育场景中经常被用于提供神经肌肉疲劳的功能性测量。然而，对疲劳最敏感的变量仍尚不完全清楚。本研究的目的是确定英式橄榄球联盟球员在季前训练期间神经肌肉疲劳的急性变化。
九名男性（年龄：19.0±1.5岁）学院英式橄榄球联盟球员在基线、基线后24小时和48小时三个时间点各进行了五次CMJ测试。疲劳方案包括与准备期和运动相匹配的多次高强度训练课程。从力-时间曲线中得出了总共14个CMJ变量。通过与基线相比的变化幅度（效应量；ES）来检验CMJ表现的有意义差异。
14个变量中的9个，在基线后24小时显示出大幅下降。平均向心功率、峰值速度、跳跃高度和零速度时的力受到的损害最大（ES = -0.98至-1.57）。在基线后48小时，首次观察到离心持续时间、向心持续时间和总持续时间大幅增加（ES = 0.48至0.61）。与此同时，峰值功率、峰值速度和跳跃高度恢复到了基线水平。
在后期再生阶段，神经肌肉疲劳可能表现为运动策略的改变，而不是像跳跃高度等身体输出的简单降低。因此，建议从业者在试图识别与拉长-缩短周期诱导的疲劳相关的双峰恢复模式中的细微变化时，纳入广泛的变量。
