The purpose of this study is to examine the relationship of competitive ability to body composition, limb composition, and limb muscle strength in varsity Sumo wrestlers. The subjects were 26 varsity Sumo wrestlers. We measured the following parameters: body height, body weight, body composition [percent body fat (%Fat) and lean body mass (LBM)] by the underwater weighing method, skinfold thickness and muscle thickness of the limbs by the B-mode ultrasonic method, and thigh strength and upper arm strength at five angle velocities (-60,0,60,180, and 300 degree·s-1)using a Cybex isokinetic dynamometer. We divided the subjects into an upper group (U group: n=14) and lower group (L group: n=12) on the basis of their competitive ability, and analyzed the measurement results. The following results were obtained.
1) The LBM of the U group was significantly higher (P <0.05) than that of the L group.However, there was no significant difference in body weight and %Fat between the groups.
2) In terms of the muscle thickness on the front of the upper arm, front of the forearm, and back of the lower leg, the U group showed significantly higher values (P <0.05) in comparison with the L group.Moreover, in terms of cross-sectional area of elbow flexor muscles calculated from the muscle thickness, the U group showed a significantly higher value (P <0.05) in comparison with the L group.However, there was no significant difference in skinfold thickness between the groups in any position.
3) In terms of thigh strength, comprising knee extension strength and knee flexion strength, the U group showed significantly higher values (P <0.05 or P <0.01) at all angle velocities in comparison with the L group.
4) The intergroup difference in knee flexion strength tended to increase as the angle velocity rose. The intergroup difference was within 24-29% at-60,0, and 60 degree·s-1,36% at 180 degree·s-1, and 39% at 300 degree·s-1. In terms of knee extension strength, however, there was no relation between the intergroup difference and the angle velocity, and the differences were within 21-31%.
5) In terms of upper arm strength, comprising elbow extension strength and elbow flexion strength, there was no significant difference between the U group and the L group at any angle velocity. These results suggest that LBM, limb muscle mass, and thigh strength, especially knee flexion strength at middle and high angle velocities, play an important role in winning in Sumo wrestling.
