Effect of creatine loading on anaerobic performance and skeletal muscle volume in NCAA division I athletes

OBJECTIVE: We measured the effect of 3 d of creatine (Cr) supplementation on repeated sprint performance and thigh muscle volume in elite power athletes. METHODS: Ten male (mean ± standard deviation of body mass and percentage of fat (81.1 ± 10.5 kg and 9.8 ± 3.5) and ten female (58.4 ± 5.3 kg and 15.0 ± 3.4) athletes were matched for sex and 10-s cycle sprint scores, paired by rank, and randomly assigned to the Cr or placebo (P) group. Subjects completed six maximal 10-s cycle sprints interspersed with 60 s of recovery before and after 3 d of Cr (0.35 g/kg of fat-free mass) or P (maltodextrin) ingestion. Before and after supplementation, 10 contiguous transaxial images of both thighs were obtained with magnetic resonance imaging. RESULTS: Cr supplementation resulted in statistically significant increases in body mass (0.9 ± 0.1 kg, P < 0.03), total work during the first sprint ( P < 0.04), and peak power during sprints 2 to 6 ( P < 0.10). As expected, total work and peak power values for males were greater than those for their female counterparts during the initial sprint ( P < 0.02); however, the reverse was true during the last three sprints ( P < 0.01). Imaging data showed a 6.6% increase in thigh volume in five of six Cr subjects ( P = 0.05). CONCLUSION: These data indicate that 3 d of Cr supplementation can increase thigh muscle volume and may enhance cycle sprint performance in elite power athletes; moreover, this effect is greater in females as sprints are repeated.