EFFECT OF CREATINE SUPPLEMENTATION ON SPRINT EXERCISE PERFORMANCE ANDMUSCLE METABOLISM

The aim of the present study was to examine the effect of creatine sup plementation (CrS) on sprint exercise performance and skeletal muscle anaerobic metabolism during and after sprint exercise. Eight active, u ntrained men performed a 20-s maximal sprint on an air-braked cycle er gometer after 5 days of CrS [30 g creatine (Cr) + 30 g dextrose per da y] or placebo (30 g dextrose per day). The trials were separated by 4 wk, and a double-blind crossover design was used. Muscle and blood sam ples were obtained at rest, immediately after exercise, and after 2 mi n of passive recovery. CrS increased the muscle total Cr content (9.5 +/- 2.0%, P < 0.05, mean +/- SE); however, 20-s sprint performance was not improved by CrS. Similarly, the magnitude of the degradation or a ccumulation of muscle (e.g., adenine nucleotides, phosphocreatine, ino sine 5'-monophosphate, lactate, and glycogen) and plasma metabolites ( e.g., lactate, hypoxanthine, and ammonia/ammonium) were also unaffecte d by CrS during exercise or recovery. These data demonstrated that CrS increased muscle total Cr content, but the increase did not induce an improved sprint exercise performance or alterations in anaerobic musc le metabolism.