There is no denying it. Carbohydrate is the most important macronutrient when it comes to fueling endurance performance. Without enough, performance can suffer, and you may experience the dreaded “bonk” (when muscle glycogen becomes depleted). Adequate carbohydrate consumption, especially during racing and training, ensures blood glucose levels remain elevated and provides the energy need to sustain muscular contractions. It also helps spare precious muscle glycogen. This is especially true as the intensity and duration of endurance exercise increases.
Depending on the length and intensity of sports such as running and cycling, different amounts of carbohydrate should be consumed to provide enough energy without causing stomach distress or bloating. This article will briefly discuss carbohydrate recommendations for endurance exercise lasting from 30 minutes to 3 hours and above. The amounts discussed here can be obtained from sports drinks, gels, chews, bars, or whole food sources and is largely determined by one’s personal preference. The type of carbohydrate (i.e., maltodextrin, fructose, glucose, dextrose, etc….) won’t matter until you start consuming over 60 grams of carbs/hour (discussed later in this article).
If your run, ride, or other endurance activity lasts 30 minutes or less, there is no need to consume carbohydrate during racing and training. Your body has more than enough muscle glycogen and blood glucose to provide adequate energy for the duration of the session.
Carb consumption can help here, especially when the intensity is “all out” for the duration of the endurance activity. Eating/drinking 30 grams of carbs per hour will provide enough energy to help you reach the finish line feeling powerful and strong.
As endurance exercise starts to go beyond 2 hours, there is a dose-response relationship showing higher amounts of carbs are needed to continue to fuel optimal performance. 60 grams of carbs per hour is the recommendation here as long as it doesn’t cause stomach problems. In a future article, we will discuss how to train the gut to tolerate higher amounts of carbs.
As we start to enter the ultra-distance and beyond zone, it makes sense more carbs are needed. 90 grams of carbs per hour is recommended but with one caveat. The type of carbohydrate used should not be exclusive (i.e., just using fructose) since amounts over 60 grams per hour from a single source can cause stomach distress. Instead, multiple transport carbohydrates should be used. Although this sounds overly complicated, it is as simple as making sure your drink, chews, gels, etc. contain a combination of carb sources such as glucose, sucrose, and fructose. This will ensure maximal absorption while minimizing the gut discomfort.
Without a doubt, carbohydrate is the most important energy-yielding nutrient for optimizing endurance performance. Furthermore, lack of dietary carbohydrate has been linked to performance limitations in these sports. According to Smith-Ryan and Antonio (2013), “strategic carbohydrate consumption before, during, and after exercise training should be a foremost concern for athletes to maximize muscle glycogen levels before the onset of exercise, as well to provide energy to muscle during exercise and hasten recovery of glycogen after exercise is complete.”
Jeukendrup, A. E. Nutrition for endurance sports: marathon, triathlon, and road cycling." J Sports Sci 29 Suppl 1: S91-99, 2011.
Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise." Sports Med 44 Suppl 1: 25-33, 2014.
Smith-Ryan, A., & Antonio, J. (Eds.). (2013). Sports Nutrition & Performance Enhancing Supplements. Linus Learning.