Laboratory Motricité, Interactions, Performance (EA 4334), University of Nantes, Nantes, France.
Med Sci Sports Exerc. 2012 Nov;44(11):2154-64. doi: 10.1249/MSS.0b013e3182625423.
This study was designed to assess muscle coordination during a specific all-out sprint cycling task (Sprint). The aim was to estimate the EMG activity level of each muscle group by referring to the submaximal cycling condition (Sub150 W) and to test the hypothesis that a maximal activity is reached for all of the muscles during Sprint.
Fifteen well-trained cyclists were tested during submaximal and sprint cycling exercises and a series of maximal voluntary contractions (MVCs) in isometric and isokinetic modes (MVC at the three lower limb joints). Crank torque and surface EMG signals for 11 lower limb muscles were continuously measured.
Results showed that Sprint induced a very large increase of EMG activity level for the hip flexors (multiplied by 7-9 from 150 W to Sprint) and the knee flexors and hip extensors (multiplied by 5-7), whereas plantar flexors and knee extensors demonstrated a lower increase (multiplied by 2-3). During Sprint, EMG activity level failed to reach a maximal value for hamstrings, tibialis anterior, tensor fasciae latae, and gluteus maximus (i.e., <70% to 80% of peak EMG activity during MVC, P < 0.05 to P < 0.001), and individual EMG patterns demonstrated a significant earlier onset and/or later offset for the majority of the muscles (P < 0.01 to P < 0.001).
Results clearly suggest a change in the relative contribution of the different muscles to the power production between Sub150 W and Sprint, and provide evidence that EMG activity level is not systematically maximal for all muscles involved in the all-out sprint cycling task. The longer period of activity induced during Sprint is likely to represent an interesting coordination strategy to enhance the work generated by all of the muscle groups.
本研究旨在评估特定全力冲刺自行车任务（冲刺）中的肌肉协调。目的是通过参考亚最大骑行条件（Sub150W）来估计每个肌肉群的 EMG 活动水平，并测试以下假设：即所有肌肉在冲刺期间都达到最大活动水平。
15 名训练有素的自行车运动员在亚最大和冲刺自行车运动以及一系列最大自主收缩（等长和等速模式下的 MVC 在下肢三个关节）中进行了测试。连续测量曲柄扭矩和 11 个下肢肌肉的表面肌电图信号。
结果表明，冲刺引起了髋屈肌（从 150W 到冲刺时增加 7-9 倍）、膝屈肌和髋伸肌（增加 5-7 倍）的 EMG 活动水平大幅增加，而跖屈肌和膝伸肌的增加幅度较小（增加 2-3 倍）。在冲刺期间，腘绳肌、胫骨前肌、阔筋膜张肌和臀大肌的 EMG 活动水平未能达到最大（即，在 MVC 期间的最大 EMG 活动的<70%至 80%，P<0.05 至 P<0.001），并且大多数肌肉的个体 EMG 模式显示出明显更早的起始和/或更晚的偏移（P<0.01 至 P<0.001）。
结果清楚地表明，在 Sub150W 和冲刺之间，不同肌肉对功率产生的相对贡献发生了变化，并提供了证据表明，并非所有参与全力冲刺自行车任务的肌肉的 EMG 活动水平都系统地达到最大。在冲刺期间引起的较长活动期可能代表一种有趣的协调策略，可增强所有肌肉群产生的工作。
