Burnett R A, Laidlaw D H, Enoka R M
Department of Kinesiology and Applied Physiology, University of Colorado, Boulder, Colorado 80309-0354, USA.
J Appl Physiol (1985). 2000 Jul;89(1):61-71. doi: 10.1152/jappl.2000.89.1.61.
The purpose of the study was to determine the association between steadiness and activation of the agonist and antagonist muscles during isometric and anisometric contractions. Young (n = 14) and old (n = 15) adults used the first dorsal interosseus muscle to perform constant-force and constant-load tasks (2.5, 5, 20, 50, and 75% maximum) with the left index finger. Steadiness was quantified as the coefficient of variation of force and the SD of acceleration normalized to the load lifted. The old adults were less steady at most target forces with isometric contractions (2.5, 5, and 50%) and with most loads during the anisometric contractions (2.5, 5, and 20%). Furthermore, the old adults were less steady when performing lengthening contractions (up to 50%) compared with shortening contractions, whereas there was no difference for young adults. The reduced steadiness exhibited by the old adults during these tasks was not associated with differences in the average level of agonist muscle electromyogram or with coactivation of the antagonist muscle.
本研究的目的是确定在等长收缩和非等长收缩过程中，稳定性与主动肌和拮抗肌激活之间的关联。年轻成年人（n = 14）和老年成年人（n = 15）使用第一背侧骨间肌，用左手食指执行恒力和恒负荷任务（最大力量的2.5%、5%、20%、50%和75%）。稳定性通过力量变异系数和加速度标准差（标准化为举起的负荷）来量化。在等长收缩（2.5%、5%和50%）时的大多数目标力量下，以及在非等长收缩期间的大多数负荷（2.5%、5%和20%）下，老年成年人的稳定性较差。此外，与缩短收缩相比，老年成年人在进行延长收缩（高达50%）时稳定性较差，而年轻成年人则没有差异。老年成年人在这些任务中表现出的稳定性降低与主动肌肌电图的平均水平差异或拮抗肌的共同激活无关。
