Ludvig Daniel, Whitmore Mariah W, Perreault Eric J
Annu Int Conf IEEE Eng Med Biol Soc. 2020 Jul;2020:3807-3810. doi: 10.1109/EMBC44109.2020.9175898.
Completing motor tasks that require contact is dependent on an ability to regulate the relationship between limb motions and interaction forces with the environment. This can be achieved by exploiting the mechanical properties of a limb or through active regulation of joint torques through changes in muscle activation. Leveraging the mechanical properties of a joint might simplify neural control when they are matched to the functional requirements of a task. The purpose of this study was to determine if humans change their control strategy, relying on limb mechanics rather than regulated muscle activation, when feasible. This was accomplished by measuring ankle impedance and muscle activation strategies in three tasks requiring joint torques to: oppose movement, assist movement, or remain constant during movement. We found that subjects produced more torque due to impedance and less torque due to muscle activation in the torque-oppose task, the only task that could feasibly be completed through impedance modulation. These results demonstrate that people do leverage the mechanical properties of a joint to complete certain task, lessening the need for precisely timed muscle contractions.
完成需要接触的运动任务取决于调节肢体运动与环境相互作用力之间关系的能力。这可以通过利用肢体的机械特性或通过改变肌肉激活来主动调节关节扭矩来实现。当关节的机械特性与任务的功能要求相匹配时，利用这些特性可能会简化神经控制。本研究的目的是确定在可行的情况下，人类是否会改变其控制策略，即依靠肢体力学而非调节肌肉激活。这是通过在三项任务中测量踝关节阻抗和肌肉激活策略来实现的，这三项任务要求关节扭矩在运动过程中：对抗运动、辅助运动或保持恒定。我们发现，在扭矩对抗任务中，受试者由于阻抗产生的扭矩更多，而由于肌肉激活产生的扭矩更少，这是唯一一项可以通过阻抗调制切实完成的任务。这些结果表明，人们确实会利用关节的机械特性来完成某些任务，从而减少对精确计时肌肉收缩的需求。
