Hall Patrick T, Crouch Dustin L
University of Tennessee, Knoxville - Department of Mechanical, Aerospace, and Biomedical Engineering, United States.
University of Tennessee, Knoxville - Department of Mechanical, Aerospace, and Biomedical Engineering, United States.
J Biomech. 2020 Apr 16;103:109685. doi: 10.1016/j.jbiomech.2020.109685. Epub 2020 Feb 26.
Passive shoulder exoskeletons, which provide continuous anti-gravitational force at the shoulder, could assist with dynamic shoulder elevation movements involved in activities of daily living and rehabilitation exercises. However, prior biomechanical studies of these exoskeletons primarily focused on static overhead tasks. In this study, we evaluated how continuous passive anti-gravity assistance affects able-bodied neuromuscular activity and shoulder kinematics during dynamic and static phases of shoulder elevation movements. Subjects, seated upright, elevated the shoulder from a rest posture (arm relaxed at the side) to a target shoulder elevation angle of 90°. Subjects performed the movement in the frontal (abduction) and scapular (scaption) planes with and without passive anti-gravity assistance. Muscles that contribute to positive shoulder elevation, based on their reported moment arms, had significantly lower muscle activations with assistance during both dynamic and static elevation. Muscles that contribute to negative shoulder elevation, which can decelerate the shoulder during dynamic shoulder elevation, were not significantly different between assistance conditions. This may be partly explained by the trend of subjects to reduce their maximum angular decelerations near the target to offset the positive shoulder elevation moment due to the anti-gravity assistance. Our results suggest that passive anti-gravity assistance could reduce the muscle activations needed to perform dynamic movements. Consequently, the anti-gravity assistance of passive shoulder exoskeletons may enhance motor function and reduce muscle and joint loads for both able-bodied and disabled users.
被动式肩部外骨骼可在肩部提供持续的反重力，有助于进行日常生活活动和康复锻炼中涉及的动态肩部抬高动作。然而，此前对这些外骨骼的生物力学研究主要集中在静态过头任务上。在本研究中，我们评估了持续的被动反重力辅助在肩部抬高动作的动态和静态阶段如何影响健康人的神经肌肉活动和肩部运动学。受试者直立坐姿，将肩部从休息姿势（手臂垂于身侧放松）抬高至目标肩部抬高角度90°。受试者在有和没有被动反重力辅助的情况下，在额状面（外展）和肩胛面（肩胛平面）进行该动作。根据报告的力臂，对正向肩部抬高有贡献的肌肉，在动态和静态抬高过程中，辅助时的肌肉激活明显较低。对负向肩部抬高有贡献的肌肉，即在动态肩部抬高过程中可使肩部减速的肌肉，在辅助条件之间没有显著差异。这可能部分是由于受试者倾向于在接近目标时降低其最大角加速度，以抵消反重力辅助产生的正向肩部抬高力矩。我们的结果表明，被动反重力辅助可减少进行动态动作所需的肌肉激活。因此，被动式肩部外骨骼的反重力辅助可能会增强健全人和残疾人的运动功能，并减轻肌肉和关节负荷。
