Wang Yun, Watanabe Kazuhiko, Asaka Tadayoshi
a Tianjin Key Lab of Exercise Physiology and Sports Medicine, Department of Health and Exercise Science , Tianjin University of Sport , Hexi District , Tianjin , China.
Res Sports Med. 2015;23(1):88-101. doi: 10.1080/15438627.2014.975808.
The aim of this article was to explore age-related differences in the muscle modes (M-modes) during voluntary body sway (VS). M-modes were defined as trunk and leg muscles organized into groups with parallel scaling of muscle activation level within a group. We hypothesized that, in comparison with young performers, older adults would show changes in the compositions of M-modes stabilizing the anterior-posterior (AP) center of pressure (COP) displacement. Young (27.5 ± 7.3 yr, 164.6 ± 9.7 cm and 58.4 ± 10.6 kg) and older (69.4 ± 6.4 yr, 160.0 ± 7.0 cm and 58.9 ± 7.5 kg) subjects performed the VS task in the AP direction while trying to minimize sway in the medio-lateral direction. EMG signals of 10 postural muscles were recorded and analyzed. Principal component analysis (PCA) was used to identify three M-modes within the space of integrated indices of muscle activity. The main findings were (1) that there were no age-related differences in magnitude of the COP displacement or amount of variance explained by the principal components (m-modes), and (2) that the number of times co-contraction and mixed m-modes were used were significantly higher for older adults, and the number of times reciprocal m-modes were used were significantly higher for young adults. These observations suggest that aging is associated with a reduced ability to unite dorsal and ventral muscles of the body, which may be reflective of the CNS developing a useful strategy when faced with self-triggered perturbations.
本文旨在探讨在自主身体摆动（VS）过程中肌肉模式（M模式）的年龄相关差异。M模式被定义为躯干和腿部肌肉组织成群，且组内肌肉激活水平呈平行缩放。我们假设，与年轻表演者相比，老年人在稳定前后（AP）压力中心（COP）位移的M模式组成上会出现变化。年轻受试者（27.5±7.3岁，身高164.6±9.7厘米，体重58.4±10.6千克）和老年受试者（69.4±6.4岁，身高160.0±7.0厘米，体重58.9±7.5千克）在AP方向上执行VS任务，同时尽量减少在内外侧方向上的摆动。记录并分析了10块姿势肌肉的肌电信号。主成分分析（PCA）用于在肌肉活动综合指标空间内识别三种M模式。主要发现为：（1）COP位移幅度或主成分（m模式）解释的方差量不存在年龄相关差异；（2）老年人同时收缩和混合M模式的使用次数显著更高，而年轻人交替M模式的使用次数显著更高。这些观察结果表明，衰老与身体背侧和腹侧肌肉联合能力的下降有关，这可能反映了中枢神经系统在面对自我触发的扰动时制定了一种有用的策略。
