MUSCLE CREATINE LOADING IN MEN

The effect of dietary creatine supplementation on skeletal muscle crea tine accumulation and subsequent degradation and on urinary creatinine excretion was investigated in 31 male subjects who ingested creatine in different quantities over varying time periods. Muscle total creati ne concentration increased by similar to 20% after 6 days of creatine supplementation at a rate of 20 g/day. This elevated concentration was maintained when supplementation was continued at a rate of 2 g/day fo r a further 30 days. In the absence of 2 g/day supplementation, total creatine concentration gradually declined, such that 30 days after the cessation of supplementation the concentration was no different from the presupplementation value. During this period, urinary creatinine e xcretion was correspondingly increased. A similar, but more gradual, 2 0% increase in muscle total creatine concentration was observed over a period of 28 days when supplementation was undertaken at a rate of 3 g/day. In conclusion, a rapid way to ''creatine load'' human skeletal muscle is to ingest 20 g of creatine far 6 days. This elevated tissue concentration can then be maintained by ingestion of 2 g/day thereafte r. The ingestion of 3 g creatine/day is in the long term likely to be as effective at raising tissue levels as this higher dose.