This study aimed to investigate: 1) the effect of optic flow speed manipulation on active participation during robot-assisted treadmill walking (RATW), 2) the influence of the type of virtual environment, and 3) the level of motion sickness and enjoyment. Twenty-eight healthy older adults were randomized in two groups: "stimulus rich" Park group (50% male, 61± 6 year) and "stimulus poor" Hallway group (43% male, 62± 5 year). Subjects walked in the Lokomat with immersive virtual reality (VR) with a matched, slow and fast optic flow speed, each lasting 7 minutes. Active participation was measured by continuously assessing the human-machine interaction torques at the hip and knee joints and muscle activity of the Vastus Medialis and Biceps Femoris. Motion sickness and enjoyment were assessed with the Simulator Sickness Questionnaire (SSQ) and Physical Activity Enjoyment Scale (PACES) respectively. In both groups optic flow speed manipulation in both directions led to a decrease in bilateral hip interaction torques towards flexion at the end of the stance phase compared to matched speed. In the Hallway group, walking with slow optic flow elicited 32% more muscle activity of the Vastus Medialis. There were no significant differences between both groups for the SSQ and PACES. Optic flow speed manipulation appears to have only a small effect on the active participation of healthy people during RATW. The type of virtual environment did not affect their activity, motion sickness or enjoyment. However, the addition of immersive VR during RATW was well tolerated and enjoyable. Further research with patients is necessary.

中文翻译：

---

健康成人机器人辅助跑步机行走过程中视线流速对主动参与的影响。

这项研究旨在调查：1）机器人辅助跑步机行走（RATW）期间光流速度操纵对主动参与的影响； 2）虚拟环境类型的影响； 3）晕车和娱乐程度。28名健康的老年人被随机分为两组：“刺激性丰富”的Park组（男性50％，61±6岁）和“刺激性较差”的Hallway组（男性43％，62±5岁）。受试者在沉浸式虚拟现实（VR）中以匹配，缓慢和快速的视光流动速度走进Lokomat，每次持续7分钟。通过持续评估髋关节和膝关节的人机交互扭矩以及内翻肌和肱二头肌的肌肉活动来测量主动参与。晕动病和娱乐性分别通过“模拟疾病问卷”（SSQ）和“体育活动享受量表”（PACES）进行评估。在两组中，与匹配速度相比，在两个方向上的光学流速度操纵导致在站立阶段结束时朝向屈曲的双侧髋关节交互作用扭矩减小。在“走廊”组中，以缓慢的视光流行走会引起内翻肌的肌肉活动增加32％。两组之间的SSQ和PACES没有显着差异。光学流速控制似乎对RATW期间健康人的积极参与影响很小。虚拟环境的类型不影响其活动，晕车或娱乐。但是，在RATW期间添加沉浸式VR的容忍度很高且令人愉快。