GREENVILLE, S.C.—Contrary to past studies, supplementing with creatine did not improve endurance performance in cyclists, although it did increase creatine levels in muscle and plasma (J Intl Soc Sports Nutr. 2010;7:26. DOI: 10.1186/1550-2783-7-26). Researchers from East Carolina University studied 12 endurance-trained male cyclists, who received either 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 in the previous three months.
Creatine supplementation significantly increased resting muscle total creatine (24.5±10 percent) and muscle creatine phosphate (38.4±23.9 percent). However, when the men were tested on an ergometer for a two-hour cycling exercise, performing at 60 percent VO2 peak with three 10-second sprints at 110-percent VO2peak ever 15 minutes, there was no difference in performance between the athletes taking creatine and those on placebo. There was a slight decrease (10 percent) in submaximal oxygen consumption in the creatine group, but no effect on respiratory exchange ratio.
The outcome was different than previous trials, which have shown a benefit to creatine supplementation in endurance performance. However, the East Carolina University team noted those studies were shorter (around five days), and often at higher ingestion levels (up to 25 g/d); subjects were also not blinded to their intervention and their performance was partially self-evaluated.