Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary T2N IN4, Canada.
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary T2N IN4, Canada.
J Biomech. 2023 Nov;160:111814. doi: 10.1016/j.jbiomech.2023.111814. Epub 2023 Oct 5.
Mechanical power is a key performance indicator in long track speed skating. Maximal power output in athletic performance can be achieved when mechanical properties of muscles, such as the force-length relationship, are optimized. The purpose of this study was to determine the in vivo operating range of vastus lateralis (VL) fascicle lengths during speed skating imitation and compare the fascicle lengths to those that define the VL force-length relationship. Sixteen sub-elite long track speed skaters (7 females and 9 males; body mass: 72.5 [11.5] kg; age: 22.1 [2.7] years) performed maximal voluntary isometric knee extensions at nine different knee joint positions (20-120°) on the left leg to obtain the maximal vastus lateralis (VL) force-length relationship. Participants then performed a speed skating imitation exercise, the turn-cable, at three progressive perceived efforts (50%, 75%, 100%) to identify the VL fascicle excursion during a complete imitation skating stroke. Fascicle lengths and knee joint angles were examined at initial-contact, peak EMG, and take-off. Fascicles between initial contact and peak EMG covered the descending limb of both the maximal and submaximal force-length relationships while operating over the plateau region from peak EMG to take-off. We conclude that the VL works at sub-optimal length during the gliding phase of skating, but at optimal length for maximal force production during the crucial push-off phase where propulsion is provided.
机械功率是长道速滑的关键性能指标。当肌肉的机械特性（如力-长关系）得到优化时，运动表现中的最大功率输出即可实现。本研究旨在确定在速滑模仿过程中股外侧肌（VL）肌束长度的体内工作范围，并将肌束长度与定义 VL 力-长关系的长度进行比较。16 名次精英长道速滑运动员（7 名女性和 9 名男性；体重：72.5 [11.5] 公斤；年龄：22.1 [2.7] 岁）在左腿上进行了九种不同的膝关节位置（20-120°）的最大自主等长膝关节伸展运动，以获得最大的股外侧肌（VL）力-长关系。然后，参与者以三种不同的感知努力（50%、75%、100%）进行速滑模仿运动，即转弯电缆运动，以确定在完整的模仿滑冰动作中 VL 肌束的运动范围。在初始接触、峰值肌电图和起飞时检查肌束长度和膝关节角度。在初始接触和峰值肌电图之间的肌束覆盖了最大和次最大力-长关系的下降支，而在从峰值肌电图到起飞的平台区域则以最优长度运行。我们得出结论，VL 在滑冰的滑行阶段以次最优长度工作，但在提供推进力的关键蹬离阶段以最大力产生的最佳长度工作。
