Walberg Rankin, J., Rockwell, J., & Toderico, B. (1999). Effect of oral creatine during energy restriction in athletes. Medicine and Science in Sports and Exercise, 31(5), Supplement abstract 365.

Anaerobic performance and body protein have been shown to decrease during periods of energy restriction (e.g., dieting). The purpose of this study was to determine if creatine supplementation during energy restriction would affect performance and body composition. Resistance-trained males (N = 16) were tested on an anaerobic cycle test (10 sprints, 30-s rest interval) before and after four days of energy restriction (18 kcal/kg) and daily creatine or placebo supplementation. A control group completed only the performance test and hydrostatic testing and showed no changes over the time of the study.

Muscle biopsies showed the placebo group decreased in total creatine and creatine phosphate (6% and 8% respectively), while the creatine group increased 16% and 17% respectively. Both groups decreased in bodyweight, fat, and nitrogen. The creatine group had less reduction in fat-free mass (-1.4% vs -2.4%) during energy restriction. The creatine group performed 3.8% more while the placebo group declined 0.5%.

Implication. Oral creatine supplementation reversed creatine loss during energy restriction. This reversal was reflected in improved anaerobic performance. Athletes undergoing weight loss programs should supplement their diets with creatine to maintain anaerobic performance.

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