A lot has been written and discussed about carbohydrates recently. One thing however is certain: those who want to be able to call on their full performance potential, especially during prolonged activities, require the appropriate intake of carbohydrates. In the following text you find out why this macronutrient is so important and how it can optimally be used during exercise!
‘How’ the intake of carbohydrates during exercise can improve performance
Among the most important mechanisms why carbohydrates during exercise can delay the signs of fatigue and can improve performance are:
- The function as an energy supplier
Carbohydrates can be stored in the body in energy stores; the so-called glycogen stores in the liver and muscles. If these stores are depleted, then high intensity exercise can no longer be continued. If the glycogen availability in the muscle and liver is low, then the correct carbohydrate intake during exercise can help maintain blood sugar levels and delivers energy for muscle work.
- The effect on the brain:
Carbohydrates can also improve performance without ‘actually’ swallowing them rinsing the mouth for several seconds with carbohydrates activates certain receptors in the oral mucosa. This results in a stimulation of the central nervous system in the brain, which can have an immediate performance enhancing effect. Keeping carbohydrate containing drinks and gels in your mouth for longer can therefore be quite useful – especially during short, intense exercise durations where the glycogen stores are not performance limiting, and therefore carbohydrates aren’t necessarily required as ‘actual’ energy suppliers.
Optimal amounts of carbohydrates during exercise
The recommended amount of carbohydrates depends primarily on the duration of the activity and the intensity, and incidentally is independent of body weight (1):
| Duration of exercise | Scientifically recommended amount of carbohydrates per hour |
| 30–75 minutes | Mouth rinse with a carbohydrate solution and/or a very small amount of carbohydrates |
| 1–2 hours | 30 g carbohydrates/hour |
| 2–3 hours | 60 g carbohydrates/hour |
| >2,5 -3 hours | Up to 90 g carbohydrates/hour |
During low intensity exercise, (e.g. easy rides, a kick about with friends), the amount of carbohydrates during activity is a little bit lower than shown in the table. Due to lower absolute exercise intensities rookies also require less carbohydrates compared to elite athletes. If the main aim of training is the optimisation of fat metabolism as opposed to performance, then carbohydrates aren’t necessary or at all sensible.
The correct carbohydrate strategy can improve performance and reduce the risk for gastrointestinal distress. Sebastian Kienle, one of the best German triathletes and winner of the Ironman Hawaii 2014 speaks from experience: ‘The maximal amount of carbohydrates you can consume during the bike and running leg is often critical to the outcome of the competition’. During a long-distance triathlon event he typically consumes on average 85g carbohydrates per hour via a glucose-fructose-mix. A special ratio of glucose and fructose sources (e.g. C2Max) is advantageous for very high carbohydrate intakes as it can increase the carbohydrate delivery to the muscles. Studies have shown that this can lead to an improvement in prolonged exercise performance (>2.5 hours) (2,3).
However, the individual tolerance is a deciding factor when it comes to the optimal amount of carbohydrates! ‘Through a slow increase in carbohydrate intake during training sessions I tested what my personal maximum is’, says Sebastian Kienle. Especially if a high carbohydrate intake during exercise is desired the motto needs to be: ‘Train your gut like your legs.’ This is because the gut is namely a highly adaptable organ. Therefore, it seems useful for instance to regularly integrate carbohydrates in the training routine. This may improve the absorption capacity of carbohydrates in the gut and simultaneously can minimise digestive issues (4) – and ultimately increase endurance performance.
From theory into practice
Nutrition during exercise can influence a successful performance or drops in performance (in the worst case even a total performance termination). There is no ‘one-size-fits-all’ strategy as the best possible nutrition strategy is different from sport to sport and is dependent on individual factors. A rough guide for long and intense cycling or running sessions or events is: there should be a timely and regular intake of carbohydrates and fluids; approx. every 15-20 minutes. During team sports such as football, ice hockey or basketball the breaks in play, as well as any other opportunities, should be used for energy and fluid intake.
In order to create an individual carbohydrate strategy, one should have a vague idea how many carbohydrates certain foods contain. For example, a medium sized banana has a carbohydrate content of approximately 25-30g, a gel typically 20-30g per sachet, and 500mL of isotonic sports drink approximately 25-30g. The exact carbohydrate content of foods can be found in the nutrition tables on the product packaging and for loose foods or homemade snacks online calculators can be used.
Whether ripe bananas, low-fat rice cakes, gels, sports drinks or specific carbohydrate bars are better suited as a fuel source needs to be individually determined according to preference and tolerance as well as the type and intensity of the activity. For example, sports drinks and gels are mostly more suitable than solid foods during very high exercise intensities. During very long endurance activities a combination of solid foods and liquid / semi-liquid foods can lead to a comfortable feeling in the stomach and also offers a welcome change which prevents monotony. Important: do not experiment with new foods, drinks or amounts during competition!
Author: Corinne Mäder Reinhard, International Sports Nutrition Lead at Active Nutrition International. She has a postgraduate diploma in Sports Nutrition from the International Olympic Committee and is a certified Sports Nutritionist from the International Society of Sports Nutrition.
Disclaimer
The implementation of the nutrition information and recommendations described in this article is done at your own risk and cannot replace a personal and individual consultation. Especially individuals under the age of 18 years, with health restrictions (especially those with orthopaedic or internistic complaints / illnesses, or food intolerances or allergies), during pregnancy or lactation should first consult a doctor. Should any complaints develop during the implementation of the nutrition recommendations a doctor should be consulted immediately. Active Nutrition International GmbH does not assume liability.
References:
- Jeukendrup, A. (2014). A Step Towards Personalized Sports Nutrition: Carbohydrate Intake During Exercise. Sports Med, 44 (Suppl 1):S25–S33.
- Currell, K. & Jeukendrup, A.E. (2008): Superior endurance performance with ingestion of multiple transportable carbohydrates; Med Sci Sports Exerc, 40:275–281.
- Stellingwerff,T., & Cox, G.R. (2014): Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Appl Physiol Nutr Metab, 39(9):998-1011.
- Jeukendrup, A. (2017). Training the Gut for Athletes. Sports Med (2017) 47 (Suppl 1):S101–S110
