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

本研究旨在探讨青春期前力量训练对青春期前男孩和女孩上臂肌肉力量和横截面积的影响。研究对象为99名健康的小学一年级、三年级和五年级儿童，他们被分成两组：训练组(N=52)和对照组(N=47)。训练组进行为期12周的力量训练，训练内容包括最大持续屈肘等长收缩10s，对照组在此期间不进行专项训练。为了确定训练后的变化，用超声方法测量了上臂组织的横截面积，包括整个组织、肌肉、脂肪和骨骼。用等速Cybex测力仪测量肘屈伸的最大等长肌力和等速肌力。以评估生理成熟度的发展。…采用TW~2法更多的是通过拍摄手腕X光照片来估计每个受试者的骨骼年龄。训练12周后，训练组(2.52 cm~2，8.9%)和对照组(2.11 cm~2，7.3%)全组织横截面积均显著增加。这一增加一方面是由于训练组的肌肉和骨骼面积显著增加，另一方面是因为对照组只有脂肪面积显著增加。在训练组中，肌肉面积的增加大约是成人研究结果的50%(Fukunaga，1978)。肌肉横截面积的增加与骨龄呈显著正相关(r=0.36，p&lt；0.01)。肘关节伸展的等长力量显著增加(1.17公斤，17.5%)，五年级男性的等长力量增加约为成人的40%，而等速力量随着训练的增加没有变化。除5年级男生训练组外，单位横截面积肌力均无明显提高。总而言之，力量训练对青春期前儿童横截面肌肉面积和肌肉力量的影响在方向上与成人相似，但在幅度上与成人不同。较少

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