Awai L, Franz M, Easthope C S, Vallery H, Curt A, Bolliger M
Spinal Cord Injury Center, Balgrist University Hospital, Forchstrasse 340, 8008, Zurich, Switzerland.
Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, 33 Queen Square, London, WC1N 3BG, UK.
J Neuroeng Rehabil. 2017 Apr 4;14(1):25. doi: 10.1186/s12984-017-0239-9.
Body weight supported locomotor training was shown to improve walking function in neurological patients and is often performed on a treadmill. However, walking on a treadmill does not mimic natural walking for several reasons: absent self-initiation, less active retraction of leg required and altered afferent input. The superiority of overground training has been suggested in humans and was shown in rats demonstrating greater plasticity especially in descending pathways compared to treadmill training. We therefore developed a body weight support system allowing unrestricted overground walking with minimal interfering forces to train neurological patients. The present study investigated the influence of different amounts of body weight support on gait in healthy individuals.
Kinematic and electromyographic data of 19 healthy individuals were recorded during overground walking at different levels of body weight support (0, 10, 20, 30, 40, and 50%). Upper body inclination, lower body joint angles and multi-joint coordination as well as time-distance parameters were calculated. Continuous data were analyzed with regard to distinct changes within a gait cycle across all unloading conditions.
Temporal gait parameters were most sensitive to changes in body unloading while spatial variables (step length, joint angles) showed modest responses when unloaded by as much as 50% body weight. The activation of the gastrocnemius muscle showed a gradual decrease with increasing unloading while the biceps femoris muscle showed increased activity levels at 50% unloading. These changes occurred during stance phase while swing phase activity remained unaltered.
Healthy individuals were able to keep their walking kinematics strikingly constant even when unloaded by half of their body weight, suggesting that the weight support system permits a physiological gait pattern. However, maintaining a given walking speed using close-to-normal kinematics while being unloaded was achieved by adapting muscle activity patterns. Interestingly, the required propulsion to maintain speed was not achieved by means of increased gastrocnemius activity at push-off, but rather through elevated biceps femoris activity while retracting the leg during stance phase. It remains to be investigated to what extent neurological patients with gait disorders are able to adapt their gait pattern in response to body unloading.
体重支持式运动训练已被证明可改善神经疾病患者的步行功能，且通常在跑步机上进行。然而，在跑步机上行走无法模拟自然行走，原因如下：缺乏自我启动、所需的腿部主动后缩较少以及传入输入改变。有人提出地面训练在人类中具有优越性，并且在大鼠实验中表明，与跑步机训练相比，地面训练具有更大的可塑性，尤其是在下行通路中。因此，我们开发了一种体重支持系统，允许在干扰力最小的情况下进行无限制的地面行走，以训练神经疾病患者。本研究调查了不同程度的体重支持对健康个体步态的影响。
记录了19名健康个体在不同体重支持水平（0%、10%、20%、30%、40%和50%）的地面行走过程中的运动学和肌电图数据。计算了上身倾斜度、下肢关节角度和多关节协调性以及时间-距离参数。对连续数据进行分析，以观察在所有卸载条件下步态周期内的明显变化。
时间步态参数对身体卸载变化最为敏感，而空间变量（步长、关节角度）在体重卸载高达50%时反应较小。腓肠肌的激活随着卸载增加而逐渐降低，而股二头肌在50%卸载时活动水平增加。这些变化发生在站立期，而摆动期活动保持不变。
即使体重卸载一半，健康个体仍能显著保持其行走运动学不变，这表明体重支持系统允许生理性步态模式。然而，在卸载状态下通过接近正常的运动学来维持给定的步行速度需要适应肌肉活动模式。有趣的是，在蹬离时维持速度所需的推进力并非通过增加腓肠肌活动来实现，而是通过在站立期腿部后缩时提高股二头肌活动来实现。步态障碍的神经疾病患者在多大程度上能够根据身体卸载来调整其步态模式仍有待研究。
