Creatine Has No Impact on Endurance Cycling Performance

GREENVILLE, S.C.Creatine supplementation does increase volumes of the compound in muscle and plasma, but does not appear to impact performance parameters in endurance cyclists, according to a new trial (J Intl Soc Sports Nutr. 2010;7:26. DOI: 10.1186/1550-2783-7-26). Researchers from the Human Performance Laboratory at East Carolina University aimed to determine whether ingestion of creatine monohydrate for one month before a prolonged endurance exercise could improve sprint performance.

The team recruited 12 adult male, endurance-trained cyclists, who were randomized to receive 3 g/d of creatine monohydrate (provided by Experimental & Applied Sciences) or placebo for 28 days. The cyclists had been training for at least a year, and had not consumed creatine or other dietary supplements except a multivitamin and/or carbohydrate beverages for at least three months prior to start of intervention. Cyclists were then tested for peak aerobic capacity and body composition 48 hours prior to a two-hour bout of cycling on an ergometer, which consisted of performing at 60 percent VO2peak with three 10-second sprints at 110-percent VO2peak every 15 minutes.

Creatine supplementation significantly increased resting muscle total creatine (24.5±10 percent) and muscle creatine phosphate (38.4±23.9 percent). While plasma glucose, blood lactate, respiratory exchange ratio and VO2peak were unaffected by creatine supplementation, riders taking creatine did see a 10 percent decrease in submaximal oxygen consumption. However, the time of the final sprint to exhaustion was not affected by creatine supplementation, nor was power output for the sprint.

The researchers noted the outcome was different than some previous trials that have shown creatine supplementation improved power output during endurance exercise; however, the trials were of much shorter duration (~5 days) and did not blind study participants to the active/placebo intervention. Also, the previous trials focused on interval-type performance rather than constant power output with sprint to exhaustion.