Department of Kinesiology and Health, Miami University, 204A Phillips Hall, 420 S. Oak St., Oxford, OH, 45056, USA.
Department of Statistics, Miami University, 308 Upham Hall, Oxford, OH, 45056, USA.
Exp Brain Res. 2020 May;238(5):1285-1292. doi: 10.1007/s00221-020-05809-8. Epub 2020 Apr 18.
Humans employ anticipatory muscle activation when catching under conditions of load uncertainty. Questions addressed were (a) on what information referent do catchers base their anticipatory neuromotor control when catching balls of unknown weight?, and (b) how do catchers use this functional referent? Thirty-six participants caught visually identical balls dropped from 0.75 m. Participants performed 40 trials, half with knowledge of ball weight and half without. Group L caught balls with a large weight range, while group S caught balls with a smaller range of weights. EMG integrals were computed for the ball flight period in five muscles. Anticipatory EMG integrals in the unknown weight condition were normalized to anticipatory EMG integrals for the maximum, minimum and average ball weights in the known ball weight condition. We assumed participants would base anticipatory control in the unknown weight condition on similar information, regardless of group. Therefore, differences in normalized EMG integrals between groups L and S would suggest that the specific referent tested (e.g., minimum possible ball weight) was not used to scale anticipatory muscle activation under load uncertainty. Independent sample t tests ascertained differences in normalized EMG integrals between groups L and S. The results suggested that the information referent participants used to catch balls of an unknown weight was knowledge of the maximum ball weight. Participants used this referent to generate a submaximal level of anticipatory muscle activation, i.e., about 93.2% of that used to catch the heaviest ball when ball weight was known in advance.
当在负载不确定的情况下接球时，人类会预先激活肌肉。研究的问题是：（a）接球者在不知道球重的情况下，他们的神经运动控制是基于什么信息参考来进行的？（b）接球者如何使用这个功能参考？36 名参与者接住了从 0.75 米高处掉落的视觉上相同的球。参与者进行了 40 次试验，其中一半是在知道球重的情况下，一半是在不知道的情况下。组 L 接住了重量范围较大的球，而组 S 接住了重量范围较小的球。在球飞行期间，计算了五个肌肉的肌电图积分。在未知重量条件下的预期肌电图积分被归一化为已知球重条件下最大、最小和平均球重的预期肌电图积分。我们假设参与者将在未知重量条件下的预期控制基于类似的信息，而不管组如何。因此，组 L 和 S 之间归一化肌电图积分的差异将表明，所测试的特定参考（例如，最小可能的球重）未用于在负载不确定的情况下对预期肌肉激活进行缩放。独立样本 t 检验确定了组 L 和 S 之间归一化肌电图积分的差异。结果表明，参与者用来接住未知重量的球的信息参考是对最大球重的了解。参与者使用这个参考来产生一个亚最大水平的预期肌肉激活，即在预先知道球重时，大约是接球最重球时使用的肌肉激活水平的 93.2%。
