What Is The Optimal Carbohydrate Concentration of Sports Drink?

This question was reignited in me the other day when I was looking at the new Nuun Endurance formula that had begun popping up, which was touted as being for exercise longer than 90 minutes. It’s pretty well established that racing performance benefits from carbohydrate supplementation in efforts longer than that time. I quickly did the math on the Nuun product (16g carbs for the suggested dilution of 16oz (=453g) in case I’m not doing it right) and came out with 3.5%. Under the 6-8% range that I’d got use the hearing over the last 15-20 years from scientific reviews like this.

They’re numbers I hadn’t forgotten as I was at University of Melbourne at a time when a Dr. Febbraio was running an exercise physiology lab largely studying carbohydrate metabolism and I was a willing guinea pig for many experiments. I vaguely remember one where we were blindly given drinks of 4%, 6% and 8% concentration and made to ride 100km on a trainer each time. Anyways, it turns out MOST sport drinks (Gatorade, Powerade etc.) are still formulated in the 6-8% carb range. Why? Because it was found when you get over 8% your gut can’t absorb it properly and you start getting gastric discomfort. There has been some research that if you mix different TYPES of carbohydrate, they are absorbed by different gut transporters and you can get up to 10-11% concentrations through the gut.

So what’s wrong with Nuun’s product being so dilute? Doesn’t that avoid the risk of any gut absorption related problems? Yes, but in efforts from 2.5 to 6 hours (Olympic to 70.3 type efforts) I usually recommend mostly, if not all, liquid ingestion of carbs (as opposed to solids or even gels) again to avoid gastric discomfort. The recommendation of carbohydate supplementation per hour is in the 60g-80g range per hour. You’d have to drink a LOT of Nuun Endurance fluid to hit that mark. Like 2 and a half 24oz cycling bidons over a 2.5 hour Olympic distance. That’s a lot of fluid if it’s not really warm and you don’t sweat a lot.

So, I always kind of come back to Gatorade Endurance, which is 6.5%, tastes good to me and you can find it pre-mixed. Which means you can’t stuff up the concentration by buying the powder and mixing it wrong at 4am in the morning before the race. Also, as an Ironman sponsor, it’s the one available on course nutrition where it’s free! I’ve done races where the volunteers are mixing huge tubs of sports drink. Would definitely not trust that because it is important you get the mix right, not just for the carbs but for the other electrolytes in there (sodium etc.).

The other point to make here is you can train your gut to absorb these carbohydrates. Which is why you’re always hearing coaches telling you the importance of training using your nutrition strategy. You may experience less gastro discomfort the day of your race if you’ve used the product before. Pretty simple. I do like to just train with just water in the pre-season, even on long rides, because I think it works your fat metabolism a bit better and I just need to lose weight but if you have a sensitive gut it’s worth putting sports drink in your bottle as the races approach.

And now comes the curveball. You may have heard of Maurtens, the sports drink all the elite runners are using. There’s two versions, 160 which has a regulation 7.8% concentration and 320 which has DOUBLE. Nearly 16%. There’s some gibberish on the website about hydrogels making it possible for this high concentration of carbohydrate to be transported by the gut. Maybe so. I’m always wary of the elite athlete testimonials, call me cynical but who knows exactly what is in those Maurtens branded bottles. It reminds me of the stories of the Newton Running sponsored athletes who shaved the lugs off of their shoes (the whole point of the shoe). I did find one very recent independent study of cross-country skiers which reported no gastric problems ingesting the high concentration Maurtens solution. Then again, it was cold and there is not as much jiggling of the insides with skiing compared to running. I’ve also had athletes use it reporting no difficulties, however they also drank water alongside it which may have diluted the concentration in the gut. So the jury is out pending more research on the Maurtens.

I’ll update this blog if I stumble on more stuff or get told I can’t use a calculator.