Hot conditions improve power output during repeated cycling sprints without modifying neuromuscular fatigue characteristics
Hot conditions improve power output during repeated cycling sprints without modifying neuromuscular fatigue characteristics
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DOI：
10.1007/s00421-012-2444-3
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发表时间：
2013-02-01
影响因子：
3
通讯作者：
Racinais, S.
中科院分区：
文献类型：
--
作者：
Girard, Olivier;Bishop, D. J.;Racinais, S.
本研究探讨了高温条件对重复短跑循环性能和运动后等长膝关节伸展功能的影响。12名身体活跃的参与者在循环力计上进行10次6秒的“全力”冲刺（恢复= 30秒），然后在6分钟后在中性环境（24摄氏度/ 30% rH）或炎热环境（35摄氏度/ 40% rH）中进行5次6秒的冲刺（恢复= 30秒）。在运动前后分别进行神经肌肉测试，包括自主和电诱发的膝关节伸肌等距收缩。运动时的平均核心温度在高温环境中高于中性环境（分别为38.0 +/- 0.1℃和37.7 +/- 0.1℃，P < 0.05）。在重复过程中，峰值功率输出下降（从冲刺1到冲刺10 - 17.9%，从冲刺11到冲刺15 - 17.0%;P < 0.001）。在高温条件下，前10次冲刺的平均峰值输出功率更高（+ 3.1%;P < 0.01）。无论环境温度如何，在运动后的短暂收缩期间，最大强度（- 12%）和力发展速率（- 15%至- 26%，距离收缩开始30-200 ms）均下降（P < 0.001）。在短暂的最大收缩期间，自愿激活的变化（类似80%）不受运动或温度的影响。自发性活动在持续收缩期间下降（P < 0.01），运动后下降更为明显（P < 0.05），但不受环境温度的影响。静息抽搐幅度下降了42% (P < 0.001)，与环境温度无关。总之，在没有高温的情况下，热暴露对重复循环短跑后等长膝关节伸肌疲劳的模式和程度没有影响。
This study investigated the effect of hot conditions on repeated sprint cycling performance and post-exercise alterations in isometric knee extension function. Twelve physically active participants performed 10 x 6-s "all-out" sprints on a cycle ergometer (recovery = 30 s), followed 6 min later by 5 x 6-s sprints (recovery = 30 s) in either a neutral (24 A degrees C/30 %rH) or a hot (35 A degrees C/40 %rH) environment. Neuromuscular tests including voluntary and electrically evoked isometric contractions of the knee extensors were performed before and after exercise. Average core temperature during exercise was higher (38.0 +/- A 0.1 vs. 37.7 +/- A 0.1 A degrees C, respectively; P < 0.05) in hot versus neutral environments. Peak power output decreased (-17.9 % from sprint 1 to sprint 10 and -17.0 % from sprint 11 to sprint 15; P < 0.001) across repetitions. Average peak power output during the first ten sprints was higher (+3.1 %; P < 0.01) in the hot ambient temperature condition. Maximal strength (-12 %) and rate of force development (-15 to -26 %, 30-200 ms from the onset of contraction) decreased (P < 0.001) during brief contractions after exercise, irrespectively of the ambient temperature. During brief maximal contractions, changes in voluntary activation (similar to 80 %) were not affected by exercise or temperature. Voluntary activation declined (P < 0.01) during the sustained contraction, with these reductions being more pronounced (P < 0.05) after exercise but not affected by the ambient temperature. Resting twitch amplitude declined (P < 0.001) by similar to 42 %, independently of the ambient temperature. In conclusion, heat exposure has no effect on the pattern and the extent of isometric knee extensor fatigue following repeated cycling sprints in the absence of hyperthermia.