The heavier the arm, the higher the action: the effects of forearm-weight changes on reach-to-grasp movements.
The heavier the arm, the higher the action: the effects of forearm-weight changes on reach-to-grasp movements.
复制标题
手臂越重，动作越高：前臂重量变化对抓握动作的影响。
DOI：
10.1007/s00221-022-06350-6
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Ando L. and Itaguchi Y.
中科院分区：
文献类型：
--
作者：
寒川雅之;野間春生;Ando L. and Itaguchi Y.
通常，我们的身体动作是在重力的作用下进行的。大多数使用力场的研究都集中在对水平面上施加的力的适应过程上，这对我们来说是新的，但不是在重力方向上的力。本研究简单地通过增加参与者前臂的重量，研究了朝重力方向的力对伸手抓住动作的运动学以及对力的短期适应的直接影响(后效)。健康的年轻成年人在三种体重条件下进行了10个伸手抓握动作的块；随着块之间的重量变化，参与者经历了从 − 200g到 + 200g的体重变化。我们获得了三个主要结果：第一，前臂重量变轻后立即运动轨迹的高度(轨迹高度)显著高于重量变重后的运动轨迹高度，这表明参与者以与前一次试验中相同的肌肉力量规划轨迹高度。第二，只有在200克条件下，受试者才能达到与无负重条件下相同的轨迹高度，至少在10次200克负荷的适应期内是不可能达到相同高度的。第三，前臂重量变化后，伸展和抓握部件之间的协调性立即保持不变。这些发现可能有助于进一步理解我们如何在日常生活中不可避免的频繁改变体重的情况下进行适应性伸手抓握动作。
Usually, our bodily movements are performed against gravity. Most studies using a force field have focused on adaptation processes to force applied in the horizontal plane, which is novel to us, but not to force in the gravitational direction. The present study investigated the immediate effects (aftereffects) of a force toward the gravitational direction on the kinematics of reach-to-grasp movements as well as short-term adaptation to the force, simply by adding a weight to participants’ forearm. Healthy young adults performed blocks of 10 reach-to-grasp movements under three weight conditions; as the weights were changed between blocks, the participants experienced weight changes ranging from − 200 to + 200 g. We obtained three main results; first, the height of movement trajectory (trajectory height) was remarkably higher immediately after the forearm weight changed to lighter than after the weight changed to heavier, suggesting that participants planed the trajectory height with the same muscle efforts as in the previous trial. Second, the trajectory height at the end of the block became higher only in 200 g condition, indicating that the participants could not achieve same trajectory height as that without any weight load, at least in ten trials of adaptation period to the 200 g weight load. Third, the coordination between reach and grasp components was preserved immediately after forearm-weight changes. These findings may contribute to further understand how we perform adaptive reach-to-grasp movements with frequent weight changes that are inevitable in everyday life.