Ohtonen O, Lindinger S J, Göpfert C, Rapp W, Linnamo V
Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Vuokatti, Finland.
Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria.
Scand J Med Sci Sports. 2018 Feb;28(2):479-486. doi: 10.1111/sms.12913. Epub 2017 Jun 7.
This study investigated how the fatigue caused by a 20-km simulated skating cross-country skiing race on snow affects the final spurt performance from a biomechanical perspective. Subjects performed a 100-m maximal skiing trial before and at the end of the simulated race. Cycle characteristics, ground reaction forces from skis and poles, and muscle activity from eight muscles were recorded during each trial. Results showed that subjects were in a fatigued state after the simulated race manifested by 11.6% lower skiing speed (P<.01). The lower skiing speed was related to an 8.0% decrease in cycle rate (P<.01), whereas cycle length was slightly decreased (tendency). In temporal patterns, relative kick time was increased (10.9%, P<.01) while relative poling time was slightly decreased (tendency). Vertical ski force production decreased by 8.3% while pole force production decreased by 26.0% (both, P<.01). Muscle activation was generally decreased in upper (39.2%) and lower body (30.7%) (both, P<.01). Together these findings show different responses to fatigue in the upper and lower body. In ski forces, fatigue was observed via longer force production times while force production levels decreased only slightly. Pole forces showed equal force production times in the fatigued state while force production level decreased threefold compared to the ski forces.
本研究从生物力学角度调查了在雪上进行20公里模拟越野滑雪比赛所导致的疲劳如何影响最后的冲刺表现。受试者在模拟比赛前和结束时进行了100米的最大滑雪测试。在每次测试期间记录了周期特征、来自滑雪板和滑雪杖的地面反作用力以及八块肌肉的肌肉活动。结果显示，模拟比赛后受试者处于疲劳状态，表现为滑雪速度降低了11.6%（P<0.01）。较低的滑雪速度与周期率降低8.0%有关（P<0.01），而周期长度略有下降（有下降趋势）。在时间模式方面，相对蹬地时间增加（10.9%，P<0.01），而相对撑杖时间略有下降（有下降趋势）。滑雪板垂直力产生下降了8.3%，而滑雪杖力产生下降了26.0%（两者均P<0.01）。上半身（39.2%）和下半身（30.7%）的肌肉激活普遍下降（两者均P<0.01）。这些发现共同表明上半身和下半身对疲劳有不同的反应。在滑雪板力方面，通过更长的力产生时间观察到疲劳，而力产生水平仅略有下降。在疲劳状态下，滑雪杖力的力产生时间相同，而与滑雪板力相比，力产生水平下降了三倍。
