Does oral creatine supplementation enhance exercise performance of female Judo athletes?

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13680057
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 体育学
• Research Institution: MEIJI UNIVERSITY
• Principal Investigator: KUWAMORI Masasuke Meiji Univ./School of Commerce /Prof, 商学部, 教授 (10192048)
• Co-Investigator(Kenkyū-buntansha): ITEYA Misaki Tokyo gakugei University School of education, Assistant professor, 教育学部, 助教授 (90292995) ; MURAMATSU Seiji Chiba University, School of education, professor, 教育学部, 教授 (40174312) ; KASUGAI Atsuo School of Political Science and Economics, Assistant professor, 政治経済学部, 助教授 (80204402)
• Project Period (FY): 2001 – 2002
• Keywords: creatine supplementation / female Judo athletes / intermittent maximal exercise / isokinetic thigh strength / body composition

Research Abstract

Introduction
The main purpose of this study is to clarify the effects of oral creatine supplementation on performance during intermittent maximal exercise and isokinetic thigh strength and of female judo athletes. In addition, we examined the effects on body composition and energy metabolism during exercise. Here, we described the performance during intermittent maximal exercise, the isokinetic thigh strength, and the body composition for the restriction of space.
Methods
Subjects : Six female Judo athletes participated in this study. Their ages were 19.67 ± 0.82 (±SD) years.
Supplement intake method and measurement period : After first measurements, the subjects ingested placebo (6 g glucose, 4 times per a day) for six days, and received second measurements in the next day. Afterwards, the subjects ingested the creatine (5 g creatine monohydrate + 1 g glucose, 4 times per a day) for six days, and received third measurements in the next day.
Performance during intermittent maximal exercise : The subjects repeated five bouts (20-s intervals) of 10-s maximal cycling.
Isokinetic thigh strength : We measured knee extension and flexion torque at each angle velocity of 0 (isometric), 60, 180, 300 degree/s.
Body composition : We used hydrodensitometry to measure the body composition. Oxygen rebreathing method was used to measure lung residual volume.
Results and discussion
Previous studies reported that the creatine supplementation strengthened the performance during intermittent intense exercise. However, in this study, all of peak power, average power, and work during 1 trial, their decreasing rate (from 1st to 5th trial), and total work did not improved after creatine supplementation. The knee e extension torque at the 180 and 300 degree/s were higher (P < 0.05) in the third measurements compared with the first measurements and the second measurements. Body weight and percent body fat increased (P < 0.05) from the first measurements to the third measurements, but fat free weight unchanged.
We conclude that oral creatine supplementation improves knee extension strength at middle and high angle velocities though it doesn't influence performance during intermittent maximal exercise and fat free weight in female Judo athletes.