Gulley Cox Lauren I, Dias Nicholas, Zhang Chuan, Zhang Yingchun, Gorniak Stacey L
Department of Health and Human Performance, University of Houston, Houston, TX, United States.
Department of Biomedical Engineering, University of Houston, Houston, TX, United States.
Exp Biol Med (Maywood). 2025 Jul 24;250:10491. doi: 10.3389/ebm.2025.10491. eCollection 2025.
The focus of this study was to evaluate motor unit number and size across the upper extremity in older adults (aged 60+ years) versus young healthy adults (aged 20-30 years). We hypothesized that older adults would have: fewer motor units and increased motor unit size as compared to young healthy adults (H1), that motor unit size would differ across the upper extremity muscles as compared to young healthy adults (H2), and higher body mass index (BMI) would be associated with lower motor unit numbers (H3). Compound muscle action potential (CMAP), motor unit number index (MUNIX), and motor unit size index (MUSIX) were evaluated in five muscles of the upper extremity. Group differences in CMAP due to aging were accounted for by increased body mass index (BMI); group differences in MUSIX were not impacted by BMI. No difference in MUNIX was found; however, an influence of BMI was found across groups. While this data provides supporting evidence of age-related motor unit changes, body composition changes with age may confound these conclusions when surface electromyography is utilized as the measurement modality. Adiposity estimation should be considered in future EMG studies, particularly in populations with higher BMI values.
本研究的重点是评估60岁及以上老年人与20 - 30岁年轻健康成年人上肢的运动单位数量和大小。我们假设，与年轻健康成年人相比，老年人会有：运动单位数量更少且运动单位大小增加（假设1），与年轻健康成年人相比，上肢肌肉的运动单位大小会有所不同（假设2），且较高的体重指数（BMI）与较低的运动单位数量相关（假设3）。在上肢的五块肌肉中评估复合肌肉动作电位（CMAP）、运动单位数量指数（MUNIX）和运动单位大小指数（MUSIX）。体重指数（BMI）增加导致了因衰老引起的CMAP组间差异；MUSIX的组间差异不受BMI影响。未发现MUNIX有差异；然而，发现BMI在各年龄组间有影响。虽然这些数据为与年龄相关的运动单位变化提供了支持性证据，但当使用表面肌电图作为测量方式时，随着年龄增长的身体成分变化可能会混淆这些结论。在未来的肌电图研究中应考虑肥胖估计，特别是在BMI值较高的人群中。
