Research on the growth, developement and trainability in muscle strength for the prepubescents

本研究的目的是确定力量训练对青春期前男孩和女孩的肌肉力量和上臂肌肉横截面积的影响。研究对象为99名健康的小学1、3、5年级儿童，分为训练组（N=52）和对照组（N=47）。训练组参加为期12周的力量训练计划，其中包括最大持续等距收缩屈曲10秒，而对照组在此期间未参加特殊训练计划。为了确定训练引起的变化，采用超声方法测量上臂组织的横截面积，如整个组织、肌肉、脂肪和骨骼。用等速cybex测力仪测量肘关节屈伸的最大等速和等速肌肉力量。以评估生理成熟度的发展。采用TW2方法，通过手-腕部x线照片估计每个受试者的骨骼年龄。经过12周的训练，训练组和对照组的全组织横截面积均显著增加（2.52 cm^2, 8.9%）和（2.11 cm^2, 7.3%）。这种增加是由于训练组肌肉和骨骼面积的显著增加，而另一方面，由于对照组脂肪面积的显著增加。在训练组中，肌肉面积的增加约为成人研究的50% （Fukunaga, 1978）。肌肉横截面积随训练的增加与骨骼年龄显著相关(r= 0。36岁的p < O.Ol)。肘部伸展的等距力量显著增加（1.17 kg, 17.5%），五年级男生的增幅约为成人的40%，而等距力量在训练中保持不变。除五年级男生外，每横截面积肌力均无显著增加。综上所述，力量训练对青春期前儿童横截肌面积和肌肉力量的影响方向与成人相似，但在程度上有所不同。少

The purpose of this study was to determine the effect of strength training in prepubescent boys and girls on muscle strength and cross-sectional area of upper arm muscle. Subjects were ninety-nine healthy elementary school children who belonged foist, 3rd and 5th grades and they were assigned to two groups of training (N=52) and control (N=47). Training group participated in strength training program for 12 weeks which consisted of maximum sustained isometric contraction of elbow flexion for ten sec, whereas control group did not participate in special training program in this period. In order to determine the changes due to training, cross-sectional areas of the tissues in upper arm, such as the whole tissue, muscle, fat and bone, were measured by the ultrasonic methods. Maximum isometric and isokinetic muscle strengths of elbow flexion and extension were measured by means of isokinetic cybex dynamometer. In order to assess the development of physological maturity. TW2 method was used … More to estimate the skeletal age in each subject by taking the hand-wrist X-ray photograph. After 12-week training period, the cross-sectional area of the whole tissue significantly increased in both training (2.52 cm^2, 8.9%) and control groups (2.11 cm^2, 7.3%). This increase was due to significant increases in muscle and bone areas in the training group and, on the other hand, due to the significant increase only in fat area in the control group. In the training group increase In muscle area was about 50% of that derived from the study on adults (Fukunaga, 1978). The increment in cross-sectional area of muscle with training was significantly correlated with the skeletal age (r=O.36, p<O.Ol). Isometric strength of elbow extension showed significant increase (1.17 kg, 17.5%) and for 5th grade males this increase was about 40% of that obtained from adults, whereas isokinetic strength unchanged with training. Muscle strength per cross-sectional area did not show a significant increase except the training group of 5th grade boys. In conclusion, the effects of strength training on cross-sectional muscle area and muscle strength for prepubescents were similar in its direction to but different in its magnitude from those found in adults. Less