Adapted from " The Athlete's Gut: The Inside Science of Digestion, Nutrition, and Stomach Distress " by Dr. Patrick Wilson courtesy of VeloPress.

Carbohydrate ingestion can improve performance under the right circumstances — and many athletes are well aware of that. So it's no coincidence that carbohydrates Beverages and dietary supplements On the fringes of sport events and at refreshment points are ubiquitous for endurance racing.

But what about the right amount of carbohydrates?
 
Against fatigue and loss of performance - the right amount is decisive!

Well-documented studies over the decades support this assumption that the consumption of carbohydrates during intense, prolonged physical activity - be it from a "scientifically based" sports drink or one Handful of sweets - can help prevent occurring Delay fatigue.( 1)
 
Yet, at the same time, consuming food (even easily digestible carbohydrates) during intense physical activity poses a challenge to the gut. Many a veteran athlete has ruined an important race or competition with a poorly planned nutritional strategy. In some of these cases, poor digestion of carbohydrates - or eating the wrong kind of carbohydrates - is the root cause. In the best case, a perfect balance should be chosen that provides the body with the optimal amount of carbohydrates and yet does not irritate the digestive tract. But there is often a fine line between not having enough carbohydrates, which can lead to hunger pangs, and too much, which immediately throws digestion out of the running.
 
Recommendations for carbohydrates during training
 
Athletes who train intensively for an hour or more daily will benefit from additional carbohydrates in their diet. This allows them to maintain muscle glycogen stores and sustain periods of intense exercise without becoming mentally and physically fatigued. Aside from consuming enough carbs every day, how much carbs should athletes consume themselves during exercise? Unfortunately, there is no simple recommendation that can be applied to every situation, as an athlete's needs depend on a number of factors.
 
The two most important factors that determine carbohydrate intake recommendations during exercise are exercise intensity and duration. Exercise intensity has a profound effect on gut physiology. As the intensity increases, blood is diverted from the intestines to meet the oxygen needs of the muscles. A simple way to think about this phenomenon is that the body only has enough blood for you to walk around. With intense exercise, the priority is not to digest what you ate for breakfast. This makes sense from an evolutionary perspective, since escaping a predator or fighting a serious threat was essential to survival. Put simply, it is difficult for the gut to tolerate much of the food intake during very intense exercise (e.g. greater than 90 percent of VO2max).
 
carbohydrate consumption

The fatigue that develops during continuous training at these very high intensities results less from the lack of carbohydrates and more from a reduction in central nervous system firing, acid-base imbalances, and impairments in muscle calcium release (6)—in short , carbohydrate consumption. Performance is unlikely to improve or fatigue to be delayed if exercise is less than an hour. During a workout longer than 60 to 90 minutes, glycogen stores will slowly become depleted. In these situations, it is beneficial to consume carbohydrates.
 

Plan carbohydrate intake properly

Glycogen deficiency and low blood sugar thus become causes of fatigue, since the duration of training exceeds one hour. With this in mind, what is the best way to plan carb intake for a longer contest?
 
First, it's important to realize that most athletes can tolerate larger amounts of carbohydrates well, since the average intensity for these events is slightly lower. Organizations such as the American College of Sports Medicine recommend that individuals consume between 30 and 90 grams of carbohydrates per hour during exercise longer than an hour 1 . This wide range of well-tolerated food intake - from as low as 30 grams to as high as 90 grams - is due to the fact that tolerance to food intake increases in parallel with exercise duration. In particular, most athletes can tolerate 30 to 60 grams of carbohydrates per hour during workouts lasting one to two and a half hours, while some can handle up to 90 grams per hour if the workout lasts longer than two and a half hours.
 
A quick calculation shows that 90 grams of carbs is about the equivalent of three large bananas or four sports gels, which is clearly not recommended for those with sensitive stomachs. If you were trying to hit that 90-gram goal with just a standard sports drink (Gatorade, Powerade, etc.), you'd have to drink 1.5 liters of it every hour. Since the majority of athletes in endurance competitions and intermittent sports consume between 0.3 and 0.6 liters per hour of fluids, most athletes attempting to consume high carbohydrate intake consume carbohydrate-rich foods along with smaller amounts of fluid. This mix of carbohydrate foods with smaller amounts of liquid allows them to avoid the dreadful stomach upset that would accompany consuming 1.5 liters of a sports drink per hour.
 
A major limiting factor in these recommendations is that they are really only intended for athletes who are pushing their physical limits and beyond. If you run a marathon and cover the distance alternately walking and jogging, you definitely don't need to consume 60 to 90 grams of carbohydrates every hour. If you are more in the midfield of the competitors, you can experiment with a smaller amount of carbohydrates (e.g. 30 to 45 grams per hour) - and thus test how the body reacts.
 
So to be able to guarantee a carbohydrate intake of 90 grams per hour, you would have to eat almost 3.5 medium-sized bananas every hour. In an important race, that seems rather exaggerated. However, one of the world's top marathon runners is a first-hand example that it's possible to consume more than 90 to 100 grams of carbohydrates per hour. This can be made possible using glucose-fructose sources. During his 2:01:39 world record Berlin marathon in 2018, Eliud Kipchoge is said to have consumed around 100 grams of carbohydrates per hour.

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Sporthunger would like to thank Dr. Patrick Wilson and Velo Press for permission to publish this excerpt. We can warmly recommend the book to you.

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