In long-duration endurance tests, it has been shown that maintaining a supplementation based on Carbohydrates (CHO) allows us to maintain our performance level throughout the duration of the test. During this type of tests, maintaining high levels of CHO in the blood throughout the duration of the test allows the athlete to maintain optimal CHO oxidation rates.
For tests lasting more than 2,5 hours, the recommended intake of CHO is 60-90 g/h (Jeukendrup, 2011). This high rate of CHO intake should be trained in the weeks prior to the competition, in order to avoid possible gastrointestinal problems, which is known as "train the gut".
In the study that we show you on this Blog (Sareban et al., 2016), they try to simulate a long-distance triathlon in the laboratory in two conditions: one with carbohydrate intake in liquid form and another with carbohydrates in gel form. The aim of the study is to observe which type of supplementation generates more gastrointestinal problems or discomfort.
To conduct the study, 9 male triathletes are selected with a VO2peak of 58,6+-6,3 ml·kg-1·min-1, a cycling power of 218+-26,5w at 90% of Ventilatory Threshold.
All triathletes follow the following race protocol during the two tests on different days:
- 60 minutes of swimming at 90% of their best time in 400m in a 25m pool.
- After swimming, the athletes are transported by car to the laboratory with an average time of 19,8+-2,4 minutes from when they finish swimming until they start the cycling segment.
- 180 minutes of cycling at 90% of Ventilatory Threshold power.
- The transition time between the cycling sector and the running sector does not exceed 4 minutes in all participants.
- 60 minutes of running at the maximum sustainable pace you can.
During the test, at the beginning and end of each discipline, the concentration of glucose and lactate in the blood is measured and weighed. In addition, every 60 minutes, besides measuring the concentration of glucose and lactate in the blood again, a measurement of gas exchange (RER) is taken, and a questionnaire on subjective perception of effort (BORG) and gastrointestinal discomfort/problems is completed.
From a nutritional level, from the end of swimming, each triathlete is given 80g of CHO per hour, divided into intakes every 15 minutes. One day, these 80g/h of CHO are administered in the form of gels (gel with 27g of CHO without caffeine). In the next trial, the CHO given are in a completely liquid form (300ml of water with 27g of CHO). In addition, in both situations, the athletes can drink water freely in the same intakes every 15 minutes to avoid dehydration.
It is also worth mentioning that the diet 48 and 4 hours before the test is controlled, and there are no differences in terms of the amount of CHO, protein, or fat.
Regarding the results, no statistical differences in performance (distance covered) were obtained in any of the 3 segments (swimming, cycling, and running) in the two conditions (gel vs. liquid).
No differences were found either regarding blood glucose and lactate concentration, nor in the variation of the athlete's weight during the test in both conditions.
On the other hand, 7 of the 9 triathletes showed gastrointestinal problems in the gel-supplemented triathlon: 5 triathletes showed stomach bloating, 1 showed stomach bloating + urgency to defecate, and 1 showed stomach bloating + defecation).
In conclusion, we can state that the intake of carbohydrates solely through gels carries a higher risk of causing gastrointestinal problems. If this method is going to be used, it must be well practiced, and it is advisable to vary the intake of carbohydrates in different textures during long-duration tests.
Bibliography:
- Jeukendrup (2011). Nutrition for endurance sports: Marathon, triathlon and road cycling. J Spots Sciences, 29(1):91-99.
- Sareban, Zügel, Koehler, Hartveg, Zügel, et al. (2016). Carbohydrate intake in form of gel is associated with increased gastrointestinal distress but not with performance differences compared with liquid carbohydrate ingestion during simulated long-distance triathlon. Int J Sport Nutrition Exc Metabolism, 26:114-122
Author:
Víctor Valldecabres. Degree in Physical Activity and Sport Sciences. Master in High Performance Sports
www.optimasportpf.es
EXPERT OPINION: at Crown Sport Nutrition we take into account the conclusions of the different scientific studies published on the subject, which is why we have developed liquid-textured gels that minimize possible gastrointestinal problems. Even so, we always recommend that you perform proper nutritional training along with different tests that combine the different forms of carbohydrate supply, such as bars (Energy Bar), gels (Energy Gel), and sports drinks (Iso&Energy Drink), in order to combine them in the best possible way, thus achieving an increase in physical performance without gastrointestinal problems.
