Guanidinoacetic Acid (GAA) Administration in Physically Active Men and Women

Glycocyamine (guanidinoacetic acid - GAA) is the biochemical precursor of creatine, which is phosphorylated and plays an important role as a high-energy carrier in the muscle. Since GAA can be administered in liquid solutions, such as sports drinks, it could be hypothesised that GAA could easily enhance creatine biosynthesis with clear physiological effects yet to be determined. No single study has examined the influence of GAA on health, human performance or body composition indicators in healthy human subjects. Moreover, the most effective dose of GAA is yet to be find. Finally, the adverse effects of GAA supplementation in humans are not determined. The main aims of the present study will be to identify if the 6-weeks of GAA supplementation improves human performance and body composition, to determine most effective dose regimens of GAA, and to analyze adverse effects of GAA supplementation. Forty eight healthy, trained (\> 2 yr training experience) male and female subjects (aged 20 to 25 years) will give their informed consent and volunteer to participate in the study, which will obtain the approval of the University's Ethical Advisory Commission. The subjects will be allocated to four randomly assigned trials: ingesting GAA (1.2, 2.4, 4.8 g of GAA in a single dose) or placebo (PLA) for 6 weeks in a double-blind design. All testing including blood and urine samples, body composition and muscle strength and exercise performance (both aerobic and anaerobic) will be conducted at presupplementation (baseline), at 1 week, at 2 weeks, at 4 weeks, at 6 weeks of supplementation and at 8 and 10 weeks (2 and 4 weeks after the end of supplementation) to analyze wash-out period. According to previous investigations, the investigators expect that ingestion of GAA will significantly increase both serum creatine and total homocystein. The investigators expect that ingestion of GAA will significantly improve muscle strength parameters and exercise performance results as compare