Comparison of Body Composition, Physical Fitness, and Knee Joint Isokinetic MUSCULAR FUNCTION of Middle School Soccer Players by Grade

Purpose: This study compared the characteristics of body composition, physique, physical fitness factors, and isokinetic muscle function by grade in middle school soccer players. Method: The results of analyzing differences in body composition and physique, physical fitness factors, and isokinetic muscle function by grade(38 in 1st grade, 46 in 2nd grade, 21 in 3rd grade) targeting 105 soccer players in S city middle school are as follows. Results: Body composition and physique factors there were significant differences by grade in height, weight, upper limb length, lower limb length, sitting height, and arm span. The post-verification of the main effects showed that height and weight were significantly higher for the second and third graders than for the first graders. For upper and lower limb length, the third graders were significantly longer than the first graders, while for sitting height, the second and third graders were significantly higher than the first graders. Fingertips were found to be significantly longer in the third graders than in the first and second graders. In physical strength factors, back muscle strength, grip strength, push-ups, sargent jump, standing long jump, side steps, shuttle run, and trunk forward flexion, trunk backward flexion, visual perception reaction, lung capacity showed significant differences by grade. As a result of post-hoc verification of the main effects by grade, the second and third graders were significantly higher than the first graders in back strength, grip strength(left, right), push-ups, and standing long jump. Sargent jump and side steps were found to be significantly higher as the grade increased, and shuttle run, visual perception reaction, and lung capacity were significantly higher for the third graders than for the first graders. Com-pared to the first and second graders, the third graders were significantly higher in trunk forward and backward flexion. In isokinetic muscular functions measured at 60 degrees of angular velocity, there were significant differences by grade in left extensor per weight(%BW), right extensor(Nm), left extensor(Nm), left flexor per weight(%BW), right flexor(Nm), and left flexor(Nm). As a result of the post-hoc verification of the main effects by grade, the third graders were significantly higher than the first graders in left extensor per weight(%BW), and the second graders were significantly higher than the first graders in right extensor(Nm), left extensor(Nm), left flexor per weight(%BW), right flexor(Nm), and left flexor(Nm). Conclusion: Based on the results of this study, the body composition, physique, physical strength factors, and isokinetic muscle function of middle school soccer players differed by grade, and considering that the less than four years of their career during the fast-growing period, the results of this study should be fully reflected in the planning of the training program.