Watanabe Kohei, Kouzaki Motoki, Ogawa Madoka, Akima Hiroshi, Moritani Toshio
1Laboratory of Neuromuscular Biomechanics, School of International Liberal Studies, Chukyo University, Yagotohonmachi, Showa-ku, Nagoya, 466-8666 Japan.
2Laboratory of Neurophysiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
Eur Rev Aging Phys Act. 2018 Apr 11;15:3. doi: 10.1186/s11556-018-0192-z. eCollection 2018.
Since age-related muscle strength loss cannot be explained solely by muscle atrophy, other determinants would also contribute to muscle strength in elderly. The present study aimed to clarify contribution of neuromuscular activation pattern to muscle strength in elderly group. From 88 elderlies (age: 61~ 83 years), multi-channel surface electromyography (EMG) of the vastus lateralis muscle was recorded with two-dimensional 64 electrodes during isometric submaximal ramp-up knee extension to assess neuromuscular activation pattern. Correlation analysis and stepwise regression analysis were performed between muscle strength and the parameters for signal amplitude and spatial distribution pattern, i.e., root mean square (RMS), correlation coefficient, and modified entropy of multi-channel surface EMG.
There was a significant correlation between muscle strength and RMS ( = 0.361, = 0.001) in the elderly. Muscle thickness ( = 0.519, < 0.001), RMS ( = 0.288, p = 0.001), and normalized RMS ( = 0.177, = 0.047) were selected as major determinants of muscle strength in stepwise regression analysis ( = 0.664 in the selected model).
These results suggest that inter-individual difference in muscle strength in elderly can be partly explained by surface EMG amplitude. We concluded that neuromuscular activation pattern is also major determinants of muscle strength on elderly in addition to indicator of muscle volume.
由于与年龄相关的肌肉力量丧失不能仅用肌肉萎缩来解释，其他决定因素也会对老年人的肌肉力量产生影响。本研究旨在阐明神经肌肉激活模式对老年组肌肉力量的贡献。从88名老年人（年龄：61~83岁）中，在等长次最大递增式膝关节伸展过程中，使用二维64电极记录股外侧肌的多通道表面肌电图（EMG），以评估神经肌肉激活模式。对肌肉力量与信号幅度和空间分布模式的参数，即多通道表面肌电图的均方根（RMS）、相关系数和修正熵进行相关分析和逐步回归分析。
老年人的肌肉力量与RMS之间存在显著相关性（r = 0.361，p = 0.001）。在逐步回归分析中，肌肉厚度（r = 0.519，p < 0.001）、RMS（r = 0.288，p = 0.001）和标准化RMS（r = 0.177，p = 0.047）被选为肌肉力量的主要决定因素（所选模型中R2 = 0.664）。
这些结果表明，老年人肌肉力量的个体差异可以部分由表面肌电图幅度来解释。我们得出结论，神经肌肉激活模式除了是肌肉体积的指标外，也是老年人肌肉力量的主要决定因素。
