Department of Biology, Mount Royal University, Calgary, AB,Canada.
School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, QLD,Australia.
J Appl Biomech. 2022 Jul 13;38(4):221-231. doi: 10.1123/jab.2021-0354. Print 2022 Aug 1.
Humans have the remarkable ability to run over variable terrains. During locomotion, however, humans are unstable in the mediolateral direction and this instability must be controlled actively-a goal that could be achieved in more ways than one. Walking research indicates that the subtalar joint absorbs energy in early stance and returns it in late stance, an attribute that is credited to the tibialis posterior muscle-tendon unit. The purpose of this study was to determine how humans (n = 11) adapt to mediolateral perturbations induced by custom-made 3D-printed "footwear" that either enhanced or reduced pronation of the subtalar joint (modeled as motion in 3 planes) while running (3 m/s). In all conditions, the subtalar joint absorbed energy (ie, negative mechanical work) in early stance followed by an immediate return of energy (ie, positive mechanical work) in late stance, demonstrating a "spring-like" behavior. These effects increased and decreased in footwear conditions that enhanced or reduced pronation (P ≤ .05), respectively. Of the recorded muscles, the tibialis posterior (P ≤ .05) appeared to actively change its activation in concert with the changes in joint energetics. We suggest that the "spring-like" behavior of the subtalar joint may be an inherent function that enables the lower limb to respond to mediolateral instabilities during running.
人类拥有在各种地形上奔跑的卓越能力。然而，在运动过程中，人类在横向方向上是不稳定的，这种不稳定性必须通过主动控制来实现——这是一个可以通过多种方式实现的目标。步行研究表明，在早期站立阶段，距下关节吸收能量，在晚期站立阶段返回能量，这一属性归因于胫骨后肌-肌腱单元。本研究的目的是确定人类（n=11）如何适应由定制的 3D 打印“鞋”引起的横向干扰，这些鞋可以增强或减少距下关节的内翻（模拟为 3 个平面的运动），同时以 3m/s 的速度跑步。在所有条件下，距下关节在早期站立时吸收能量（即负机械功），随后在晚期站立时立即返回能量（即正机械功），表现出“弹簧样”的行为。在增强或减少内翻的鞋类条件下，这些效应分别增加和减少（P≤.05）。在所记录的肌肉中，胫骨后肌（P≤.05）似乎与其关节能量变化协调一致地主动改变其激活。我们认为，距下关节的“弹簧样”行为可能是一种固有功能，使下肢能够在跑步时应对横向不稳定性。
