In April 2009 the International Journal of Sport Nutrition and Exercise Metabolism published an article by Michael Saunders and collegues at James Madison University. Saunders has made a name for himself as the leading researcher of the effects of carbohydrate-protein sports drinks on exercise performance, and this new study adds to his important body of work.

In this study, Saunders et al compared the effects of a carbohydrate-protein sports drink and a carbohydrate-only sports drink on performance in and muscle damage resulting from a simulated 60K cycling time trial. Each of the 13 trained male cyclists who participated in the study completed the time trial on two occasions: once consuming the carb-only sports drink at a rate sufficient to supply 60g of carbs per hour and once consuming the carb-protein sports drink also at a rate sufficient to supply 60g of carbs per hour.

The time trial consisted of three 20K "laps" with a 5K "climb" at an approximate 5-percent grade at the end of each. On average, the subjects completed the time trial only about 36 seconds faster when using the carb-protein sports drink. However, this entire difference was concentrated in the final 20K lap, and especially within the final 5K climb, which alone accounted for 24 seconds of that total 36-second difference. These results are statistically significant and also practically meaningful. No one would expect the addition of protein to a conventional sports drink formula to allow cyclists to blast through an entire time trial at a higher power output level, but what competitive cyclist wouldn't want to gain 24 seconds on the final climb of a race thanks to a bit of protein?

Saunders' team also took measurements of muscle damage (specifically, creatine kinase levels) and mucle soreness before the time trials and again 24 hours afterward. Increases in muscle damage and soreness were significantly attenuated in the carb-protein time trial. Less muscle damage resulting from hard rides means more usable muscle for the next ride.

It bears noting that previous studies with similar formats have been objected to on the grounds that the carb-protein sports drink provides more total calories than the carb-only sports drink, leaving open the possibility that a higher-calorie carb-only sports drink would perform just as well. However, Saunders has responded to this objection with studies comparing the effects of isocaloric carb-only and carb-protein sports drinks and has found that, while the differences in effects are somewhat smaller, they remain significant.