Protein during exercise: good for strength not endurance training


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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.

5 Replies to “Protein during exercise: good for strength not endurance training”

  1. So I think it’s highly unlikely that protein will help endurance in short events, but I’m not too sure who’s really been promoting that, most of the “use protein” pushing is in ultra endurance events.

    But even the study – 2 hours at 55% is a pretty easy workout, and what happens at sub-maximal efforts may well be quite different to maximal. So I’d like to see 6-8hour maximal workouts being studied rather than 2 hours sub-max. Mind you, I wouldn’t even play guinea pig in a 30mile indoor bike effort so I’m not sure where you’d find volunteers for an 8hour maximal one!

    However, what I want to see, although I’m not too sure how to design such a study without a massive cohort, is how protein during aids recovery – as you say it’s very important after exercise – but does taking some protein in throughout increase the immediate uptake post exercise so you’re even less delayed at getting it in than if you only consume it in your recovery drink?

  2. Thanks for the comments, Jim. A couple of points:

    “I’m not too sure who’s really been promoting that, most of the “use protein” pushing is in ultra endurance events.”

    Actually, this is pretty much exactly what companies like Accelerade have been promoting, based on research by John Ivy and others. The big claim on their website is “extends endurance 29%; improves endurance up to 40% in a subsequent workout.” Those claims come from a 2004 study at JMU: in that study, the first ride to exhaustion, at 75% VO2peak, took 82 minutes on pure carbs and 106 minutes with protein. The second ride, at 85% VO2peak, took 31 minutes on protein carbs and 43 minutes with protein — definitely not ultra-endurance events.

    “2 hours at 55% is a pretty easy workout”

    This was 55% of “workload capacity (Wmax).” I actually don’t know what that is, but it’s clearly significantly harder than 55% of VO2max, because two thirds of the subjects (who were trained, recreationally competitive cyclists) were unable to complete the trial at that level and had to lower the power to 50% Wmax during the later stages of the trial. So definitely not easy!

    “However, what I want to see… is how protein during aids recovery”

    Agreed that this is a very interesting and relevant question. Studies like the JMU one I linked to above have tried to address it (thus Accelerade’s claims that you’ll perform better the next day if you take protein during today’s workout). The fundamental challenge with this area of research is that if you equalize the number of carbs, then the protein group gets more calories (which was the case in the JMU study); if you equalize the number of calories, then the carb group gets more carbs — so it’s hard to tease out exactly what is (or isn’t) producing a difference between the two groups. Amby Burfoot had an excellent article on this in RW a few years ago.

    Ultimately, I think that’s what this study is trying to get at. Instead of looking at performance, which is confounded by factors like total calorie count, they’re looking at the basic chemistry. When we add protein during exercise, do your active muscles start synthesizing more muscle during exercise? According to this study, the answer is no. Of course, as you point out, this answer applies to two-hour bouts of exercise. I wouldn’t be surprised at all if different factors came into play during ultra-endurance events.

  3. I agree that 55% for 2hours is too little for too short a time.

    I have no idea how protein affects muscle synthesis or recovery, but I found that when I switched to a drink with protein, after 4 hours of hard racing on the bike, I didn’t feel like I had a hole in the stomach wanting to eat something other than sports drink. I’ve raced 10 hours and know people that have raced 24 and 48 hours on just sports drink with protein. I couldn’t imagine going back to the pure carb/electrolyte drink especially for a 24hour event.

    An interesting study would look at blood glucose. I wonder if the protein acts like a buffer preventing spikes and regulating hunger?

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