Carbohydrates Consumed During Exercise

By Monique Ryan | Aug. 31, 2009, 12 a.m. (ET)
You may carefully scrutinize the labels of popular sports drinks and gels, which can contain glucose, glucose polymers, maltodextrin, sucrose, fructose, and high fructose corn syrup as a carbohydrate source. But perhaps you are not sure how these sugars differ in their digestion and absorption, and quality, and which sources are ultimately the best for your athletic performance.

Consuming the wholesome carbohydrates optimal for your daily diet is of course not feasible during moderate to hard training when gastrointestinal tolerance, and fuel and fluid delivery are your top priorities.

First and foremost, you should choose a well-formulated sports drink that you like and tolerate. A mix of carbohydrates may offer the best advantages. Sports drinks that provide more than one carbohydrate source can utilize more than one transport system across the small intestine, after which they enter your bloodstream and provide fuel during exercise. Many of these products also have a moderate to high glycemic index and can quickly raise blood glucose levels during exercise when fuel stores begin to run low. Just avoid drinks in which fructose is the sole carbohydrate source as they may cause gastrointestinal distress due to the large amount of fructose.

Monique Ryan, MS, RD is the author of Sports Nutrition for Endurance Athletes, 2nd edition (VeloPress 2007). Click here to view more about the book or purchase. She was a member of the Athens 2004 Performance Enhancement Teams for USA Triathlon and USA Cycling Women’s Road Team. She is owner of Personal Nutrition Designs and offers her sports nutrition “E Program” at