Center for Rehabilitation Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
J Electromyogr Kinesiol. 2010 Aug;20(4):667-75. doi: 10.1016/j.jelekin.2009.10.007. Epub 2009 Dec 16.
The purpose of the study was to investigate the effects of two fatigue protocols on landing performance. A repeated measures design was used to examine the effects of fatigue and fatigue protocol on neuromuscular and biomechanical performance variables. Ten volunteers performed non-fatigued and fatigued landings on two days using different fatigue protocols. Repeated maximum isometric squats were used to induce fatigue on day one. Sub-maximum cycling was used to induce fatigue on day two. Isometric squat maximum voluntary contraction (MVC) was measured before and after fatigued landings on each day. During the landings, ground reaction force (GRF), knee kinematics, and electromyographic (EMG) data were recorded. Isometric MVC, GRF peaks, loading rates, impulse, knee flexion at contact, range of motion, max angular velocity, and EMG root mean square (RMS) values were compared pre- and post-fatiguing exercise and between fatigue protocols using repeated ANOVA. Fatigue decreased MVC strength (p0.05), GRF second peak, and initial impulse (p0.01), but increased quadriceps medium latency stretch reflex EMG activity (p0.012). Knee flexion at contact was 5.2 degrees greater (p0.05) during fatigued landings following the squat exercise compared to cycling. Several variables exhibited non-significant but large effect sizes when comparing the effects of fatigue and fatigue protocol. In conclusion, fatigue alters landing performance and different fatigue protocols result in different performance changes.
本研究旨在探讨两种疲劳方案对落地性能的影响。采用重复测量设计，考察疲劳和疲劳方案对神经肌肉和生物力学性能变量的影响。10 名志愿者在两天内使用两种不同的疲劳方案进行非疲劳和疲劳着陆。在第一天，通过重复最大等长深蹲来诱发疲劳。在第二天，通过亚最大循环来诱发疲劳。在每天的疲劳着陆前后测量等长最大自主收缩（MVC）。在着陆过程中，记录地面反作用力（GRF）、膝关节运动学和肌电图（EMG）数据。使用重复方差分析比较疲劳前和疲劳后以及两种疲劳方案之间的等长 MVC、GRF 峰值、加载率、冲量、接触时膝关节屈曲、运动范围、最大角速度和 EMG 均方根（RMS）值。疲劳降低了 MVC 力量（p0.05）、GRF 第二峰值和初始冲量（p0.01），但增加了股四头肌中潜伏期伸展反射 EMG 活动（p0.012）。与循环相比，在深蹲运动后的疲劳着陆中，接触时膝关节屈曲增加了 5.2 度（p0.05）。当比较疲劳和疲劳方案的影响时，几个变量表现出非显著但大的效应量。总之，疲劳会改变着陆性能，不同的疲劳方案会导致不同的性能变化。
