Falk Bareket, Usselman Charlotte, Dotan Raffy, Brunton Laura, Klentrou Panagiota, Shaw Jay, Gabriel David
Department of Physical Education and Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada.
Appl Physiol Nutr Metab. 2009 Aug;34(4):609-15. doi: 10.1139/H09-020.
Muscle strength and activation were compared in boys and men during maximal voluntary elbow flexion and extension contractions. Peak torque, peak rate of torque development (d/dmax), rate of muscle activation, and electromechanical delay (EMD) were measured in 15 boys (aged 9.7 +/- 1.6 years) and 16 men (aged 22.1 +/- 2.8 years). During flexion, peak torque was significantly lower in boys than in men (19.5 +/- 5.8 vs. 68.5 +/- 11.0 Nm, respectively; p < 0.05), even when controlling for upper-arm cross-sectional area (CSA), and peak electromyography activity. Boys also exhibited a lower normalized d/dmax (7.2 +/- 1.7 vs. 9.5 +/- 1.6 (Nm.s-1).(Nm-1), respectively; p < 0.05) and a significantly longer EMD (75.5 +/- 28.4 vs. 47.6 +/- 17.5 ms, respectively). The pattern was similar for extension, except that group differences in peak torque were no longer significant when normalized for CSA. These results suggest that children may be less able to recruit or fully utilize their higher-threshold motor units, resulting in lower dimensionally normalized maximal torque and rate of torque development.
在最大自主肘关节屈伸收缩过程中，对男孩和男性的肌肉力量与激活情况进行了比较。对15名男孩（年龄9.7±1.6岁）和16名男性（年龄22.1±2.8岁）测量了峰值扭矩、扭矩发展峰值速率（d/dmax）、肌肉激活速率和机电延迟（EMD）。在屈曲过程中，即使在控制上臂横截面积（CSA）和肌电图峰值活动的情况下，男孩的峰值扭矩仍显著低于男性（分别为19.5±5.8与68.5±11.0 Nm；p<0.05）。男孩还表现出较低的标准化d/dmax（分别为7.2±1.7与9.5±1.6（Nm·s-1）·（Nm-1）；p<0.05）以及显著更长的EMD（分别为75.5±28.4与47.6±17.5 ms）。伸展时的模式相似，只是在对CSA进行标准化后，峰值扭矩的组间差异不再显著。这些结果表明，儿童可能较难募集或充分利用其高阈值运动单位，导致在维度标准化后的最大扭矩和扭矩发展速率较低。
