虽然有几种手臂假肢模型可用，但1940年设计的身体动力型仍然是绝大多数截肢者的选择。最近的一组实验旨在比较未受损手臂和身体动力假肢的无约束运动，清楚地显示了运动控制领域其他几位研究人员注意到的离散动作现象:长而平稳的人体运动似乎由一系列连续的短动作组成。基于离散动作的性能可以洞察假肢的精度和速度限制，并证明对这种运动特征的未来研究是合理的。

ALTHOUGH SEVERAL ARM PROSTHESIS MODELS ARE AVAILABLE, THE 1940'S DESIGNED BODY-POWERED TYPE REMAINS THE CHOICE OF AN OVERWHELMING MAJORITY OF AMPUTEES. A RECENT SET OF EXPERIMENTS DESIGNED TO COMPARE UNCONSTRAINED MOTION OF THE UNIMPAIRED ARM AND BODY-POWERED PROSTHESIS CLEARLY SHOWS THE DISCRETE ACTION PHENOMENON NOTED BY SEVERAL OTHER RESEARCHERS IN THE MOTOR CONTROL FIELD: LONG, SMOOTH HUMAN MOVEMENTS APPEAR TO BE COMPOSED OF A SERIES OF SUCCESSIVE SHORT MOVEMENTS. PERFORMANCE BASED ON DISCRETE ACTIONS YIELD INSIGHT INTO ACCURACY AND SPEED CONSTRAINTS ON THE PROSTHESIS AND JUSTIFY FUTURE STUDY OF THIS FEATURE OF MOVEMENT.