Effects of oral creatine supplementation on multiple sprint cycle performance.

This study examined the influence of oral creatine monohydrate supplementation on repeated 10 s cycle ergometer sprint performance. Seventeen recreationally active males (mean +/- SD age, body mass, height, and peak oxygen uptake = 20.5 +/- 1.2 yr, 72.1 +/- 10.3 kg, 176.8 +/- 6.6 cm and 3.87 +/- 0.91 l.min-1, respectively) participated in the 16 day experiment. All subjects initially completed a VO2peak test and were then administered glucose (4 x 10 g per day) in a single blind fashion for four days, after which they completed the first series of multiple sprints (7 x 10 s). Following the sprints, subjects were matched on sprint performance and divided into two groups (n = 8, placebo (Pl); and n = 9, creatine (Cr)). For the following four days, diets were supplemented with either Cr (4 x 70 mg.kg-1 body mass per day mixed with 5 g glucose) or glucose (4 x 10 g per day); supplementation during this phase was double-blind. Subjects then repeated the multiple sprint and VO2peak tests. Measures of peak power output (PPO), mean power output (MPO), end-power output (EPO), and percent power decline were recorded during the sprints. Each 10 s sprint was separated by 30 s of passive recovery except for sprints five and six which were separated by five minutes. Venous blood was sampled at rest, immediately after sprint five, before sprint six, and following sprint seven for the analysis of plasma lactate and blood pH. Expired air was sampled for five minutes following sprint seven for the calculation of post-exercise VO2. Analysis of variance revealed that four days of Cr supplementation did not influence multiple sprint performance, plasma lactate, blood pH and excess post-sprint oxygen consumption. Furthermore, VO2peak was unchanged following Cr supplementation. The data suggest that either the four day period of Cr supplementation failed to significantly raise resting muscle [Cr], or that multiple sprint performance was not enhanced by increases in resting muscle [Cr].