Effect of Combined Intra-Session Glucose and Fructose Intake on the Performance of Young Super-Sprint Triathletes: A Randomised, Crossover, Blind, Placebo-Controlled Study

Carbohydrate intake is a commonly used strategy in sports, and supplementation for triathletes includes pre-competition, intra-competition, and post-competition intake. The consumption of fructose–glucose improves intestinal transit and gastric emptying. The main purpose of this study was to analyse the effect of intra-session carbohydrate intake in triathletes training in the super-sprint modality. Eleven adolescent triathletes (boys, n = 9, 14.6 years; girls, n = 2, 15.2 years) participated in a crossover, randomised, and blind study on the effect of supplementation with 45 g of carbohydrates (glucose:fructose; 1:2) The participants performed two super-sprint tests (swimming 250 m, cycling 6 km, and running 2 km) with a rest period (2 h) during which they drank a placebo drink (PG) or a carbohydrate drink (SG). The effect on blood glucose was evaluated, but there were no significant changes in glucose values. However, it was higher in the SG after supplementation. No significant differences were found in the cycling, swimming, and running tests, except for RPE in the swimming sector (p < 0.05). Neither were significant changes in body weight observed during the assessments. Supplementation with 45 g of liquid carbohydrates composed of fructose and glucose in a 2:1 ratio was not effective for delaying fatigue or improving performance markers or blood glucose levels in super-sprint triathletes.