According to Martin Gibala, an associate professor of kinesiology at McMaster University, "Sports drinks improve performance during prolonged exercise because of two key ingredients: carbohydrate, which provides fuel for working muscles, and sodium, which helps to maintain fluid balance. Research also supports the practice of consuming protein after exercise to promote muscle recovery. However, the alleged benefit of consuming protein during exercise is controversial."
Previous studies had found that adding approximately 2% protein to a carbohydrate sports drink increased cycle endurance capacity when compared with carbohydrate alone. But McMaster researchers felt that these studies may have been flawed because (a) the rate of carbohydrate ingestion was less than what is considered optimal for endurance performance, and (b) the exercise to fatigue performance test did not accurately represent the way in which athletes typically compete, such as a race in which a fixed distance or set amount of work is performed as quickly as possible.
The study was performed on 10 trained male cyclists who undertook an 80 km laboratory time trial every 7 days for 3 weeks. The athletes were given either a regular sports drink with 6% carbohydrate, a 6% carbohydrate sports drink that had been supplemented with 2% protein, or a non-energetic sweetened placebo drink. During the exercise subjects consumed 250 ml of their drink every 15 minutes. It was a double-blind, crossover trial with neither the participants nor the researchers being aware of which drink they were getting.
The results of the study found that, when compared to placebo, the sports drink improved performance, which confirmed what previous researchers had found. However, there was no added performance benefit from the drink with the added protein.
"Previous studies that suggested protein was beneficial used 'ride to exhaustion' tests that do not resemble normal athletic competition. In addition, the subjects in those studies received less than the optimal recommended amount of carbohydrate. Our study shows that protein confers no performance benefit during 'real life' exercise when athletes consume sufficient amounts of a sports drink," said Gibala
Sports drink manufacturers have long been looking for ingredients that can be added to their products that will help boost athletic performance, but as the research has shown, adding protein is not the answer.
"Eating a little protein after exercise is important to help repair damaged muscles and promote training adaptations," says Gibala, "but no compelling evidence suggests that endurance athletes need protein during exercise."