School of Kinesiology & Health Science, York University, Toronto, ON, Canada.
School of Kinesiology & Health Science, York University, Toronto, ON, Canada.
J Biomech. 2019 Sep 20;94:224-229. doi: 10.1016/j.jbiomech.2019.07.027. Epub 2019 Jul 31.
The type of balance recovery, feet-in-place or stepping, is predicated on the perturbation intensity, often defined by the combination of applied force and displacement. Few studies examined the relationship between characteristics required to produce a stepping response with one of the postural perturbation methods. The purpose of this study was to investigate the relationship between perturbation characteristics (applied force and displacement) required to elicit a forward stepping response with platform-translation and shoulder-pull methods, and to establish whether a common set of perturbation characteristics existed across both perturbation methods. Fourteen young healthy males participated. Temporally unexpected platform translations and shoulder pulls were induced by release of free weights, which fell a controlled height exerting a pull on the platform or on the participant via a shoulder harness. Participants responded with either feet-in-place or stepping responses. The force and displacement were varied to investigate the range of force-displacement combinations required to elicit stepping responses. Force-displacement combinations that elicited stepping responses were recorded and normalized to the participant's body weight (BW) and the base of support (BOS; participant's foot length). The lowest force and associated displacement that elicited stepping responses showed an inverse linear relationship during both platform-translation and shoulder-pull trials. The lowest force-displacement combination common to both perturbation methods was found to be 8.75%BW and 105%BOS, which, in the future work, could enable a direct comparison of the neuromuscular and biomechanical responses to different perturbation methods in a manner that attempts to equilibrate the perturbation stimulus across the methods.
平衡恢复的类型，即原地踏步或迈步，取决于扰动强度，通常由施加力和位移的组合定义。很少有研究探讨过产生迈步反应所需的特征与一种姿势扰动方法之间的关系。本研究的目的是调查平台平移和肩部拉动两种方法引起向前迈步反应所需的扰动特征（施加力和位移）之间的关系，并确定两种扰动方法是否存在共同的扰动特征。14 名年轻健康男性参加了本研究。通过释放自由重量来诱发平台突然平移和肩部突然牵拉，自由重量以受控的高度落下，对平台或通过肩带对参与者施加拉力。参与者以原地踏步或迈步的方式做出反应。改变力和位移以研究产生迈步反应所需的力-位移组合范围。记录并归一化到参与者体重（BW）和支撑基础（BOS；参与者的脚长），以产生迈步反应的力-位移组合。在平台平移和肩部牵拉试验中，引起迈步反应的最低力和相关位移呈反比线性关系。两种扰动方法共有的最低力-位移组合被发现为 8.75%BW 和 105%BOS，在未来的工作中，可以尝试在方法之间平衡扰动刺激，从而以直接比较不同扰动方法的神经肌肉和生物力学反应。
