Bring Your Own Carbs on Race Day

Sponsorships are causing race directors to put carb-free drinks on their courses, which can cause issues for those who assume hydration offerings contain needed fuel.

Some options, like carb-free Nuun, are designed for people who have trouble tolerating sugary sports drinks. Some marathons now serve them on the course.

But if you opt for carb-free drinks, you’ll need to get carbs elsewhere. Midrace carbs can improve performance by 4 to 12 minutes for a 3-hour marathoner.

The fuelling responsibility lies with the athletes. “Many athletes show up to the race and then find out what drinks there are. That’s just bad preparation,” says Trent Stellingwerff, innovation and research/physiology lead at the Canadian Sport Institute. Check the race’s website and practice consuming what they serve, down to the exact flavours and spacing between stops. Or, if you’ve already found your ideal mix, stick with it and carry it yourself.

Aim for 30 to 60 grams of carbohydrates and 350-700mL of fluid per hour of a marathon.

Nuun, Ultima Replenisher

These provide only hydration and electrolytes. Stellingwerff says they are beneficial for racing in the heat, when hydration needs increase. For a marathon, one gel every 30 minutes provides the recommended amount of carbs. Gels and food can also provide electrolytes for those who prefer plain water.


Drinking 350-700mL an hour of these beverages meets all requirements: hydration, electrolytes, and simple carbs. Both have glucose and fructose (blends improve absorption). Consider supplementing these drinks with gels, but take the gels with water to avoid overloading your system.


These drinks typically appear at trail or ultra races and contain complex carbohydrates, which are broken down more slowly. But Lisa Dorfman, author of Legally Lean, says they won’t provide “that kick that most of us need at some point during a race.” Instead, she suggests sipping on these drinks the day before the race.


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