Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta T2N 1N4, Canada; Institute of Sports and Sports Science, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany; Department of Sports Science and Sports, Friedrich Alexander University Erlangen-Nuremberg, Erlangen 91058, Germany.
J Sport Health Sci. 2022 May;11(3):330-338. doi: 10.1016/j.jshs.2021.02.003. Epub 2021 Mar 1.
The ankle and foot together contribute to over half of the positive and negative work performed by the lower limbs during running. Yet, little is known about how foot kinetics change throughout a run. The amount of negative foot work may decrease as tibialis anterior (TA) electromyography (EMG) changes throughout longer-duration runs. Therefore, we examined ankle and foot work as well as TA EMG changes throughout a changing-speed run.
Fourteen heel-striking subjects ran on a treadmill for 58 min. We collected ground reaction forces, motion capture, and EMG. Subjects ran at 110%, 100%, and 90% of their 10-km running speed and 2.8 m/s multiple times throughout the run. Foot work was evaluated using the distal rearfoot work, which provides a net estimate of all work contributors within the foot.
Positive foot work increased and positive ankle work decreased throughout the run at all speeds. At the 110% 10-km running speed, negative foot work decreased and TA EMG frequency shifted lower throughout the run. The increase in positive foot work may be attributed to increased foot joint work performed by intrinsic foot muscles. Changes in negative foot work and TA EMG frequency may indicate that the TA plays a role in negative foot work in the early stance of a run.
This study is the first to examine how the kinetic contributions of the foot change throughout a run. Future studies should investigate how increases in foot work affect running performance.
踝关节和足部在跑步时共同完成了下肢超过一半的正功和负功。然而，人们对足部动力学在跑步过程中如何变化知之甚少。随着胫骨前肌（TA）肌电图（EMG）在长时间跑步过程中的变化，负脚功的量可能会减少。因此，我们研究了整个变速跑过程中踝关节和足部的工作以及 TA 的 EMG 变化。
14 名脚跟触地的受试者在跑步机上跑步 58 分钟。我们收集了地面反作用力、运动捕捉和 EMG。受试者以 110%、100%和 90%的 10 公里跑步速度以及 2.8 m/s 的速度多次在跑步过程中进行跑步。使用远端后足功评估足部工作，这提供了足部所有工作贡献者的净估计。
在所有速度下，整个跑步过程中足部的正功增加，踝关节的正功减少。在 110%的 10 公里跑步速度下，负脚功在整个跑步过程中减少，TA EMG 频率降低。正足功的增加可能归因于内在足部肌肉在足部关节上所做的功增加。负脚功和 TA EMG 频率的变化可能表明，在跑步的早期支撑阶段，TA 在负脚功中起作用。
这项研究首次研究了足部动力学贡献在整个跑步过程中如何变化。未来的研究应该调查足部工作的增加如何影响跑步性能。
