Sports drinks containing protein are better at improving athletes' performance. Research published in BioMed Central's open access Journal of the International Society of Sports Nutrition has shown that drinks containing a mix of carbohydrate and protein are superior to carbohydrate-only drinks in improving cyclists' recovery from exercise.

John Berardi of Precision Nutrition worked with researchers from Gettysburg College and The University of Western Ontario to study which energy drink best helped cyclists recover after a strenuous ride. He said, "Liquid carbohydrate and protein supplements given early during a six hour post-exercise recovery period helped subjects better maintain subsequent time trial performance and power output, compared to supplements with carbohydrate alone".

In the test, cyclists rode exercise bikes that were attached to monitors allowing them to compete against a virtual opponent. After a morning session, they rested for six hours drinking either the protein-containing sports drink or the carbohydrate only version. Both formulas had the same energy content. After their six-hour rest, the athletes did another virtual cycle race. According to Berardi, "Both groups showed a reduction in performance in the afternoon session. However, the reduction in distance traveled and power output during the afternoon exercise was significantly less among those who had the protein and carbs drink, relative those who just had the carbs".

The subjects' self-reported fatigue levels were lower in the protein group and increases in fat oxidation were also seen. Beardi concluded, "These findings may be important considering that most endurance athletes concern themselves primarily with carbohydrate intake and often fail to recognize the potential benefits of protein with respect to performance recovery".