Background

Modifying the longitudinal bending stiffness (LBS) of footwear has become a popular method to improve sport performance. It has been demonstrated to influence running economy by altering lower extremity joint level mechanics. Previous studies have only examined within-participant effects at one running speed.

Research question

Do joint level mechanics differ in response to varying footwear LBS at a range of running speeds?

Methods

This study utilized a cross-sectional repeated measure study design using a convenience sample. Ten well trained non-rearfoot strike male distance runners ran at 3.89, 4.70, and 5.56 m/s (14, 17, 20 km/hr) in footwear of three different LBS levels. Mechanics and energetics of the metatarsophalangeal joint (MTPJ), ankle, knee, and hip joints during stance phase were assessed using an 8-camera optical motion capture system (f_s = 200 Hz), a force instrumented treadmill (f_s = 1000 Hz) and standard inverse dynamics theory.

Results

Range of motion and negative work decreased and angular stiffness increased for the MTPJ with increasing LBS at all speeds (p < .001). Peak MTPJ moment did not change at any speed in response to increased LBS. Negative work at the ankle decreased in the stiff shoe at 17 km/hr (p = .036). Peak ankle plantar flexion velocity decreased with increasing LBS at all speeds (p < .05).

Significance

While changes in MTPJ mechanics were consistent across speeds, decreased negative ankle work was only observed at 17 km/hr in the stiff shoe, suggesting that perhaps tuned footwear LBS may need to focus primarily on metabolically beneficial changes in ankle plantar flexor mechanical behavior to improve performance in distance runners. Tuning footwear stiffness may also be beneficial to clinical populations, as clinicians seek to optimize their patients’ locomotion economy.

中文翻译：

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跑步速度是否会影响非后足罢工赛跑者的关节水平力学对纵向弯曲刚度变化的鞋的响应？

背景

改变鞋的纵向弯曲刚度（LBS）已经成为改善运动表现的流行方法。它已被证明可以通过改变下肢关节水平力学来影响跑步的经济性。以前的研究仅以一种运行速度检查了参与者内部的影响。

研究问题

在不同的行驶速度下，不同级别的鞋类LBS的响应程度会有所不同吗？

方法

本研究使用方便样本进行的横断面重复测量研究设计。十名训练有素的非后足打击雄性长跑运动员以三种不同的LBS级别的鞋类以3.89、4.70和5.56 m / s（14、17、20 km / hr）的速度跑。使用8台摄像机光学运动捕捉系统（f _s = 200 Hz），带压力的跑步机（f _s = 1000 Hz ）评估站立阶段phase趾关节（MTPJ），踝关节，膝盖和髋关节的力学和能量_学）和标准逆动力学理论。

结果

在所有速度下，随着LBS的增加，MTPJ的运动范围和负功减小，并且角刚度增加（p <.001）。响应于LBS的增加，峰值MTPJ力矩没有任何变化。硬鞋中脚踝处的负功以17 km / hr的速度下降（p = .036）。在所有速度下，踝关节峰值plant屈速度均随着LBS的增加而降低（p <.05）。

意义

虽然MTPJ力学的变化在各个速度上都是一致的，但仅在硬鞋中以17 km / hr的速度观察到负踝工作减少，这表明调整后的鞋LBS可能需要主要集中于脚踝flex屈机械行为的代谢有益变化以改善在长跑运动员中的表现。由于临床医生寻求优化其患者的运动经济性，因此调整鞋类的刚度也可能对临床人群有益。