Department of Functional Anatomy, Faculty of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
J Electromyogr Kinesiol. 1991 Dec;1(4):270-80. doi: 10.1016/1050-6411(91)90014-V.
To study joint contributions in manual wheelchair propulsion, we developed a three-dimensional model of the upper extremity. The model was applied to data collected in an experiment on a wheelchair ergometer in which mechanical advantage (MA) was manipulated. Five male able-bodied subjects performed two wheelchair exercise tests (external power output P(ext) = 0.25-0.50 W · kg(-1)) against increasing speeds (1.11-1.39-1.67 m.s(-1)), which simulated MA of 0.58-0.87. Results indicated a decrease in mechanical efficiency (ME) with increasing MA that could not be related to applied forces or joint torques. Increase in P(ext) was related to increases in joint torques. On the average, the highest torques were noted in shoulder flexion and adduction (35.6 and 24.6 N · m at MA = 0.58 and P(ext)= 0.50 W · kg(-1)). Peak elbow extension and flexion torques were -10.6 and 8.5 N · m. Based on the combination of torques and electromyographic (EMG) records of upper extremity muscles, anterior deltoid and pectoralis muscles are considered the prime movers in manual wheelchair propulsion. Coordinative aspects of manual wheelchair propulsion concerning the function of (biarticular) muscles in directing the propulsive forces and the redistribution of joint torques in a closed chain are discussed. We found no conclusive evidence for the role of elbow extensors in direction of propulsive forces.
为了研究手动轮椅推进中的关节贡献，我们开发了一个上肢的三维模型。该模型应用于在轮椅测功机上进行的实验中收集的数据，在该实验中操纵了机械优势（MA）。五名男性健全受试者进行了两次轮椅运动测试（外部功率输出 P(ext) = 0.25-0.50 W · kg(-1)），速度逐渐增加（1.11-1.39-1.67 m.s(-1)），模拟 MA 为 0.58-0.87。结果表明，机械效率（ME）随着 MA 的增加而降低，这与施加的力或关节扭矩无关。增加 P(ext)与关节扭矩的增加有关。平均而言，肩部弯曲和内收时的扭矩最大（MA = 0.58 和 P(ext)= 0.50 W · kg(-1)时，分别为 35.6 和 24.6 N · m）。最大的肘伸和屈扭矩分别为-10.6 和 8.5 N · m。基于扭矩和上肢肌肉的肌电图（EMG）记录的组合，三角肌前束和胸大肌被认为是手动轮椅推进的主要推动者。讨论了手动轮椅推进中关于（双关节）肌肉在引导推进力和在封闭链中重新分配关节扭矩的协调方面。我们没有发现确凿的证据表明肘伸肌在推进力方向上的作用。
