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Does adding a bit of protein to a carb-heavy sports drink improve performance? That’s the claim of drinks like Accelerade, which boast a 4:1 ratio of carbohydrate to protein. But the research showing any performance advantage has been controversial. There’s a new study in the American Journal of Physiology: Endocrinology and Metabolism that put this to the test once again (hat tip to Amby Burfoot for pointing it out).
The study is quite complex, but basically it involved putting 12 cyclists through a two-hour cycling test at 55% maximum power while ingesting either a carbohydrate drink (at a rate of 1 gram per kilogram of body weight per hour) or a 4:1 carb-protein drink. They did a whole bunch of tests, including repeated muscle biopsies, to evaluate whether the protein boosted rates of muscle protein synthesis during exercise. The result: it didn’t.
An interesting wrinkle: the same group (from Maastricht University in the Netherlands) did an similar study on resistance training. In that case, adding protein did boost protein synthesis rates. The researchers speculate that muscle protein synthesis is blocked during actual exercise, but can take place in the short rests between sets of a strength training routine. Thus, the protein only helps for intermittent exercise.
Two final notes. First, this wasn’t a performance study, so it certainly doesn’t prove anything either way — that debate will continue, though my sense is that dominant current opinion is that protein during exercise doesn’t help endurance. Second, we’re only talking about drinks ingested during exercise; it’s clear that protein is very important after exercise.