The physiological and health effects of oral creatine supplementation

The American College of Sports Medicine Roundtable on the physiological and health effects of oral creatine supplementation. Med. Sci. Sports Exerc., Vol. 32, No. 3, pp. 706-717, 2000. Creatine (Cr) supplementation has become a common practice among professional, elite, collegiate, amateur, and recr eational athletes with the expectation of enhancing exercise performance. R esearch indicates that Cr supplementation can increase muscle phosphocreati ne (PCr) content, but not in all individuals. A high dose of 20 g.d(-1) tha t is common to many research studies is not necessary, as 3 g.d(-1) will ac hieve the same increase in PCr given time. Coincident ingestion of carbohyd rate with Cr may increase muscle uptake; however, the procedure requires a large amount of carbohydrate. Exercise performance involving short periods of extremely powerful activity can be enhanced, especially during repeated bouts of activity. This is in keeping with the theoretical importance of an elevated PCr content in skeletal muscle. Cr supplementation does nor incre ase maximal isometric strength, the rate of maximal force production, nor a erobic exercise performance. Most of the evidence has been obtained from he althy young adult male subjects with mixed athletic ability and training st atus. Less research information is available related to the alterations due to age and gender. Cr supplementation leads to weight gain within the firs t few days, likely due to water retention related to Cr uptake in the muscl e. Cr supplementation is associated with an enhanced accrual of strength in strength-training programs, a response not independent from the initial we ight gain, but may be related to a greater volume and intensity of training that can be achieved. There is no definitive evidence that Cr supplementat ion causes gastrointestinal, renal, and/or muscle cramping complications. T he potential acute effects of high-dose Cr supplementation on body fluid ba lance has not been fully investigated and ingestion of Cr before or during exercise is not recommended. There is evidence that medical use of Cr suppl ementation is warranted in certain patients (e.g., neuromuscular disease); future research may establish its potential usefulness in other medical app lications. Although Cr supplementation exhibits small but significant physi ological and performance changes, the increases in performance are realized during very specific exercise conditions. This suggests that the apparent high expectations for performance enhancement, evident by the extensive use of Cr supplementation, are inordinate.