In other blogs you can read about the indispensable role that the correct intake of carbohydrates plays during endurance exercise. It was also shown that with higher carbohydrate intakes, the ratio between glucose and fructose plays an important role in the body's absorption. But what ratio is best in each case? Are Turbo products with a 1:0.8 ratio by definition better than Energy products with a 2:1 ratio? And what is the difference between a 1:0.8 and a 1:1 ratio between glucose and fructose? You will find answers to all these questions in this blog.
In summary
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To provide more than 60 grams of carbohydrates per hour to the muscle, a mix of glucose and fructose should be taken. This ensures that multiple absorption transporters in the intestine are utilised.
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For intakes of ± 90 grams per hour, products with a 2:1 ratio of glucose to fructose offer the best balance between carbohydrate availability in the muscle, taste and gastrointestinal comfort.
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Intakes above 90 grams per hour can provide even more fuel to the muscle. A 1:0.8 ratio between glucose and fructose is the most ideal for this. This results in improved performance and recovery during extreme exertion.
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Stomach/intestinal training with the right products is necessary at all times to be able to apply this without complaints in the most important competitions.
The fundamental role of carbohydrates in sports performance
That carbohydrates are the most important source of energy for top performances in sports should be common knowledge by now. The first studies demonstrating this were conducted in the 1920s. Since the 1960s in particular, knowledge about the importance of carbohydrates has increased, especially about the role of muscle glycogen in endurance sports. 1 It was demonstrated, for example, that endurance performance improved considerably when there were sufficient carbohydrates available in the body, and that fatigue and exhaustion could be significantly delayed if endurance athletes consumed carbohydrates during exercise.2
From maltodextrin to glucose mix
For a long time, no distinction was made in the type of carbohydrate. Many studies at the time only used maltodextrin: a chain of glucose molecules that forms the fastest absorbable sugar. In the late 1990s, researchers found that the muscles could only use ± 60 grams of carbohydrates per hour as fuel. Even if the intake was (much) higher than that. Despite the lack of direct evidence for this, it led to the idea that the intestinal absorption capacity was a limiting factor. Especially when it appeared that adding other forms of glucose still led to a higher carbohydrate consumption in the muscle.3 Until 2007, the advice to endurance athletes was therefore to consume a maximum of 60 grams of carbohydrates per hour.
The optimal mix of glucose and fructose
Because glucose is absorbed by the body in the intestine via the sodium-dependent glucose transporter (SGLT1), researchers started looking for carbohydrates that are absorbed by the body via a different route. Fructose was the most interesting of these, because it is absorbed via the GLUT-5 transporter. This means that glucose and fructose can be absorbed simultaneously and independently of each other. It was quickly demonstrated that a mix of glucose and fructose indeed led to a considerably higher carbohydrate consumption in the muscles.4 The search for the ideal ratio between the two carbohydrates had officially begun.
From the studies that followed shortly after, a consensus quickly emerged that endurance athletes could increase their carbohydrate intake to as much as 90 grams per hour if the exercise lasted longer than 2.5 hours. A 2:1 ratio of glucose to fructose emerged as the ideal balance between a higher carbohydrate supply for the muscle and a pleasant taste. Fructose is very sweet, so as soon as too much was added, the products were sometimes experienced as too sweet and sticky.5 Since then, an intake of 90 grams per hour via a 2:1 ratio has become a standard guideline, and you see this ratio reflected in many contemporary sports nutrition products. It is still true that if you are aiming for an intake of up to 90 grams per hour, this 2:1 ratio offers the best balance between fuel supply and good taste.
The power of a 1:0.8 glucose-fructose mix
However, a more recent and detailed look at the research from the early years of this century showed that adding more fructose could lead to an even higher carbohydrate utilisation in the muscle. This could yield performance gains, particularly during the most extreme endurance efforts. 5 A new analysis of glucose:fructose ratios between 1:0.7 and 1:1 showed that the ratio of 1:0.8 resulted in the highest carbohydrate consumption in the muscle and should lead to the greatest improvement in performance in extreme endurance efforts. 6. Furthermore, no problems with taste and/or gastrointestinal complaints were reported.
A 2011 study confirmed this for the first time: this study showed that an intake of 110 grams of carbohydrates per hour in a 1:0.8 ratio led to a higher utilisation in the muscle than the same intake in a 2:1 ratio. In addition, the endurance performance of the first group was better than that of the second group. 6 Several studies have since confirmed that intakes of up to 120 grams per hour in a 1:0.8 ratio do indeed lead to the highest carbohydrate availability in the muscle, appear to have a beneficial effect on recovery from extreme duration and/or intensity exercise and also seem to lead to better performance. 7-12 For this reason, products with this composition are the best choice for athletes if they strive for intakes of 90 to 120 grams per hour during extreme exertion.
As described in previous blogs, training your stomach and intestines is still crucial to be able to tolerate these extremely large carbohydrate intakes during a tough training session or competition. So don't forget that in addition to selecting the right products, you also need to train with them very regularly and gradually increase the total amount of carbohydrates per hour.
References
- Bergstrom J, Hermansen L, Hultman E, and Saltin B. Diet, muscle glycogen and physical performance. Acta Physiol Scand 71: 140-150, 1967.
- Hawley JA, Schabort EJ, Noakes TD, and Dennis SC. Carbohydrate-loading and exercise performance. An update. Sports Med 24: 73-81, 1997.
- Jentjes RLPG, Moseley Lm Waring RH, Harding LK, Jeukendrup AE. Oxidation of combined ingestion of glucose and fructose during exercise. J Appl Physiol 96(4): 1277-87, 2004.
- Jeukendrup AE. Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Curr Opin Clin Nutr Metab Care 13(3): 352-7, 2010.
- Podlogar T, Wallis GA. New Horizons in Carbohydrate Research and Application for Endurance Athletes. Sports Med 52: 5-23, 2022
- O'Brien WJ, Rowlands DS. Fructose-maltodextrin ratio in a carbohydrate-electrolyte solution differentially affects exogenous carbohydrate oxidation rate, gut comfort, and performance. Am J Physiol Gastrointest Liver Physiol 300(1): 181-9, 2011.
- Rowlands DS, Houltham S, Musa-Veloso K, Brown F, Paulionis L, Bailey D. Fructose-Glucose Composite Carbohydrates and Endurance Performance: Critical Review and Future Perspectives. Sports Med 45(11): 1561-76, 2015.
- Urdampilleta A, Arribalzaga S, Viribay A, Castañeda-Babarro A, Seco-Calvo J, Mielgo-Ayuso J. Effects of 120 vs. 60 and 90 g/h Carbohydrate Intake during a Trail Marathon on Neuromuscular Function and High Intensity Run Capacity Recovery. Nutrients 12(7): 2094, 2020
- Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro A, Seco-Calvo J, Urdampilleta A. Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners. Nutrients 12(5): 1367, 2020.
- Cox GR, Snow RJ, Burke LM. Race-day carbohydrate intakes of elite triathletes contesting olympic-distance triathlon events. Int J Sport Nutr Exerc Metab 20(4): 299-306, 2010.
- Hearris MA, Pugh JN, Langan-Evans C, Mann SJ, Burke LM, Stellingwerff T, Gonzalez JT, Morton J. 13C-glucose-fructose labelling reveals comparable exogenous CHO oxidation during exercise when consuming 120 g/h in fluid, gel, jelly chew or co-ingestion. J Appl Physiol 132(6): 1394-1406, 2022
- Podlogar T, Bokal S, Wallis GA. Increased exogenous but unaltered endogenous carbohydrate oxidation with combined fructose-maltodextrin ingested at 120 g h−1 versus 90 g h−1 at different ratios. Eur J Appl Physiol, 122(11): 2393-2401, 2022.
