INDIANAPOLIS--Carbohydrate-protein sports beverages may be more effective than carbohydrate-only sports drinks at increasing endurance and inhibiting oxidative damage caused by exercise, according to a study published in the July issue of Medicine & Science in Sports & Exercise (36, 7:1233-1238, 2004) (www.ms-se.com)..

In the randomized, double blind study, 15 male cyclists rode cycles at 75 percent capacity until they reached exhaustion, and rode again 12 to 15 hours later at 85 percent capacity until exhaustion. Subjects consumed 1.8 ml/kg of body weight of a carbohydrate-only (CHO; 7.3 percent concentration) beverage or carbohydrate/protein beverage (CHO+P; 7.3 percent and 1.8 percent concentrations) every 15 minutes of exercise, and 10 ml/kg of body weight immediately after exercise. Beverages were matched for carbohydrate content, resulting in 20 percent lower total caloric content in the CHO beverage. The study was repeated 14 days later with each group receiving the opposite beverage.

In the first ride, subjects who drank the CHO+P beverage rode 29 percent longer than those administered the CHO beverage. The results of the second ride were even stronger: CHO+P consumers rode 40 percent longer than those administered the CHO beverage. Post-exercise indicators of muscle damage were 83 percent lower in those administered CHO+P than in those administered CHO. The researchers observed no significant differences in certain variables including ventilation, heart rate, blood glucose or blood lactate between treatments in either trial.

It was concluded a carbohydrate beverage with additional protein calories produced considerable improvements in time to fatigue and reductions in muscle damage in endurance athletes over a carbohydrate-only beverage. The researchers noted further research is necessary to determine whether these effects resulted from the higher total caloric content of the CHO+P beverage or to the mechanisms of its protein content.