Peyrebrune, M.C., Nevill, M.E., Donaldson, F.J., & Cosford, D.J. (1998). The effects of oral creatine supplementation on performance in single and repeated sprint swimming. Journal of Sports Science, 16(3), 271-279.

The effect of oral creatine supplementation on sprint swimming performance in elite competitive male swimmers (N = 14) was studied.

Ss performed a single sprint (1 x 50 yards [45.72 m]) and repeated sprint set (8 x 50 yards at intervals of 1 min 30 s) before and after a 5-day period of either creatine (9 gm creatine + 4.5 g maltodextrin + 4.5 gm glucose per day) or placebo (18 gm glucose per day) supplementation under a double-blind protocol. Venous and capillary blood samples were taken for the determination of plasma ammonia, blood pH and lactate.

Mean times recorded for the single 50-yard sprint were unchanged as a result of either supplementation. During the repeated sprint test, mean times increased during all trials, but performance was improved as a result of creatine supplementation (sprints 1-8: control pre-, 23.35 + 0.68 to 26.32 + 1.34 s; control post-, 23.59 + 0.66 to 26.19 + 1.48 s; creatine pre-, 23.20 + 0.67 to 26.85 + 0.42 s; creatine post-, 23.39 + 0.54 to 25.73 + 0.26 s; P < 0.03). Thus the percentage decline in performance times was reduced after creatine supplementation (control, 12.7 + 5.7% vs 11.0 + 5.5%; creatine, 15.7 + 4.3% vs 10.0 + 2.5%). The metabolic response was similar before and after supplementation, with no differences in the blood lactate or pH response. Plasma ammonia was lower on the second trial but this could not be attributed to the effect of supplementation. A further urinary analysis study supported these findings by demonstrating an approximately 67% (approximately 26 g) retention of the administered creatine in this group of swimmers after an identical supplementation regimen.