Ramsay J A, Blimkie C J, Smith K, Garner S, MacDougall J D, Sale D G
School of Physical Education and Athletics, McMaster University, Hamilton, Ontario, Canada.
Med Sci Sports Exerc. 1990 Oct;22(5):605-14. doi: 10.1249/00005768-199010000-00011.
Possible changes in muscle size and function due to resistance training were examined in prepubertal boys. Thirteen boys (9-11 yr) volunteered for each of the training and control groups. Progressive resistance training was performed three times weekly for 20 wk. Measurements consisted of the following: 1 repetition maximum (RM) bench press and leg press; maximal voluntary isometric and isokinetic elbow flexion and knee extension strength; evoked isometric contractile properties of the right elbow flexors and knee extensors; muscle cross-sectional area (CSA) by computerized tomography at the mid-right upper arm and thigh; and motor unit activation (MUA) by the interpolated twitch procedure. Training significantly increased 1 RM bench press (35%) and leg press (22%), isometric elbow flexion (37%) and knee extension strength (25% and 13% at 90 degrees and 120 degrees, respectively), isokinetic elbow flexion (26%) and knee extension (21%) strength, and evoked twitch torque of the elbow flexors (30%) and knee extensors (30%). There were no significant effects of training on the time-related contractile properties (time to peak torque, half-relaxation time), CSA, or %MUA of the elbow flexors or knee extensors. There was, however, a trend toward increased MUA for the elbow flexors and knee extensors in the trained group. Strength gains were independent of changes in muscle CSA, and the increases in twitch torque suggest possible adaptations in muscle excitation-contraction coupling. Improved motor skill coordination (especially during the early phase of training), a tendency toward increased MUA, and other undetermined neurological adaptations, including better coordination of the involved muscle groups, are likely the major determinants of the strength gains in this study.
对青春期前男孩进行了抗阻训练导致肌肉大小和功能可能变化的研究。训练组和对照组各有13名男孩（9 - 11岁）自愿参与。每周进行3次渐进性抗阻训练，共20周。测量内容包括：1次重复最大值（1RM）卧推和腿举；最大自主等长和等速肘屈和膝伸力量；右侧肘屈肌和膝伸肌的诱发等长收缩特性；通过计算机断层扫描测量右上肢上臂中部和大腿的肌肉横截面积（CSA）；以及通过内插单收缩程序测量运动单位激活（MUA）。训练显著提高了1RM卧推（35%）和腿举（22%）、等长肘屈（37%）以及膝伸力量（90度和120度时分别提高25%和13%）、等速肘屈（26%）和膝伸（21%）力量，以及肘屈肌（30%）和膝伸肌（30%）的诱发单收缩扭矩。训练对肘屈肌或膝伸肌的时间相关收缩特性（达到峰值扭矩的时间、半松弛时间）、CSA或MUA百分比没有显著影响。然而，训练组的肘屈肌和膝伸肌MUA有增加的趋势。力量增加与肌肉CSA的变化无关，单收缩扭矩的增加表明肌肉兴奋 - 收缩偶联可能发生了适应性变化。运动技能协调性的改善（尤其是在训练早期）、MUA增加的趋势以及其他未确定的神经适应性变化，包括所涉及肌肉群更好的协调性，可能是本研究中力量增加的主要决定因素。
