Runners, triathletes, and the like often ask me if midrace fueling is necessary and, if so, what types of fuel should be used. Let’s take a moment to explore when midrace fueling is needed and which products work best.

As I have discussed in previous articles, carbohydrates are the primary fuel source our bodies use when participating in endurance events. Midrace fueling is often time necessary for cardiovascular exercise lasting 90 minutes or longer. Our muscles can only hold a limited amount of carbohydrates even if we carb load the weeks/days leading up to an event. Therefore, frequent replacement is necessary.

In addition, the faster an athlete runs or cycles the higher percentage of carbohydrates will be used for fuel. As our bodies deplete muscle glycogen during extended periods of exercise, it increasingly relies on blood sugar for energy. By consuming rich carbohydrate sources during activity, blood sugar levels will maintain normalcy and your muscles will have a consistent, reliable energy source. Current recommendations are consumption of 30-60 g carbohydrates per hour in the form of liquids, gels, jelly beans, or combination of these in order to prevent “hitting the wall” or depletion of blood sugar and muscle glycogen. Let’s explore some of the fueling products on the market and their nutritional breakdown.

Traditional sports gels, blocks, jelly beans, and gummies (CLIF, Gu, Hammer, PowerBar, Honey Stinger, Huma): These are typically comprised of 2 carbohydratesources, most often maltodextrin and glucose. However, some new products are beginning to use either glucose or maltodextrin in combination with fructose from fruit because of the increased GI tolerance of fructose for some athletes. These products typically contain 20-30 g carb/packet. The benefit to using gels, gu, beans, blocks is the quick delivery of carbs to replenish sugar in blood and muscle. Consuming water with these can quicken that delivery. The current recommendation is that a runner/triathlete should consume one of these products within the first 45 mins-1 hour, then every 30-45 mins thereafter. The downside to these products is GI intolerance for some. Over the course of a marathon, a runner may consume up to 5 packets of these products, which introduces a large amount of sugar into the gut and, in turn, can cause GI distress.

Traditional sports drinks: These products offer carbohydrates in the form of liquid sugar, which allows for fast digestion and quick delivery into the bloodstream while offering a hydration source at the same time. It is recommended to choose drinks with a 6-8% carbohydrate solution. Twelve-16 fl oz will provide the recommended 30-60 g carbohydrates/hour. The downside to these products is that it may be difficult to consume this quantity while running. In contrast, cyclists may actually prefer this delivery.

UCAN “Super Starch”: This product is relatively new to the market. It is a no sugar added powdered drink product comprised of “Superstarch”, which is a non-GMO, corn derived carbohydrate source. The manufacturers claim that there is very little insulin production after consuming their product because the digestion of the carbohydrate is drastically slower than that of sugar containing products. Because of this slow digestion an athlete would not have to consume as much, as frequently in order to achieve the same blood sugar stabilizing results as some sugar based products. They offer mainly drinks, but do have some bars available, as well as, electrolyte replacement drinks. I cannot give you a personal account of how effectively this product works to maintain energy, but there are several professional athletes that tout its success.

The key to using these products is practice. During training, try out different products on the schedule you plan to consume during the race. You can base that schedule on the recommendations given above. You will feel much more confident going into a long race knowing that you are ready with the types of fuel that you are certain give you the biggest return without any risk of intolerance.


Kate H. Rountree, LDN, RDN
Lafayette General Health