2008 年 40 巻 3 号 p. 1-10
The purpose of this study is to investigate the effects of oral creatine (Cr) supplementation on isokinetic thigh strength, performance during intermittent maximal exercise and body composition of male and female judo athletes. Fourteen collegiate judo athletes (7 males and 7 females) participated in this study. After initial measurements were taken, the subjects ingested a placebo (P1) (6 g glucose; 4 times per day) for six days, and were measured again on the following day. Next, the subjects ingested the Cr (5 g Cr monohydrate + 1 g glucose; 4 times per day) for six days, and were measured again on the following day. We took three sets of measurements: 1) Isokinetic thigh strength; knee extension torque was measured at each angle velocity of 0 (isometric),60,180,300 degree/s,2) performance during intermittent maximal exercise; power and work were measured during the first trial in five bouts (20-s intervals) of 10-s maximal cycling, and the total work of the five trials was measured, as well as the decreasing rates of power and work from the first trial through to the fifth trial, and 3) body composition; the percent body fat and fat-free weight were measured using hydrodensitometry. The knee extension torque at each angle velocity of 180 and 300 degree/s increased (P<0.01 and P<0.05, respectively) before and after Cr supplementation in the female judo athletes, but did not so in the male judo athletes. In the case of angle velocities of 0 and 60 degree/s, the knee extension torque did not change significantly before and after Cr supplementation in both the male and female athletes. There was no clear change in the results of the intermittent maximal exercise test. We could not observe a significant change in either the power or the work during the first trial. There was no significant change in the decreasing rates of power and work, nor the total work. Body weight increased (P<0.05) during the experiment period (1st 3rd measurements) in both the male and female athletes. However, there was no significant change in the percent body fat and fat-free weight. These results suggest that Cr supplementation enhance dynamic thigh strength at middle and high velocity in female judo athletes, but not in male judo athletes. However, this effect does not originate from an increase of fat-free weight.
