Influence of short-term creatine supplementation on hormonal responses to resistance exercise

ABSTRACT

Creatine is a dietary supplement that is used by athletes to increase muscle mass and strength and especially to improve sports performance. The purpose of this study was to determine the influence of creatine-monohydrate supplementation on hormonal responses in resistance exercise. Twenty-seven trained men took, daily, either creatine- monohydrate [CR, n=15] or a placebo [PL, n=12] for 7 days, followed by performing exercise testing [6 sets of no more than 10 repetitions of the squat exercise at 80% of their 1RM]. Blood samples were taken at baseline and on the exercise testing day [pre-exercise [Pre], immediately post-exercise [1P], and 15 [2P] and 30 [3P] minutes post-exercise] to measure of serum growth hormone [GH] and testosterone concentrations. Significant increases in the number of repetitions [7.2 +/- 1.2] and volume of exercise [1569 +/- 1.8] were observed in the CR, as compared to PL group in set 5 of the exercise protocol. GH was significantly higher at minutes 15 [6.1 +/- 1.8 ng/ml] and 30 [3.6 +/- 1.9ng/ml] post-exercise, as compared to the pre-exercise values in the CR group. In addition, in the CR group the testosterone concentration was also significantly higher [69.1 +/- 19.2 pmol/L] at minute 15 post-exercise as compared to the pre-exercise and PL values. These results suggest that creatine supplementation can enhance acute exercise performance by increasing the number of repetitions performed and the total volume of exercise. The enhanced performance results in an increase in both GH and testosterone concentrations, indicating an augmented anabolic hormone response to creatine supplementation