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Effect of Low-To-Moderate Exogenous Carbohydrate Supplementation on Time to Exhaustion During Constant Load Intense
Janis Schierbauer1, Oscar Altenberg1, Thomas Voit1
1Division of Exercise Physiology and Metabolism, Bayreuth Centre of Sport Science, University of Bayreuth, Bayreuth, Germany.
Abstract:
Exogenous carbohydrate (CHO) supplementation during exercise is an efficient strategy to enhance endurance performance. However, the effects of low-to-moderate amounts of exogenous CHO on time to exhaustion (TTE) have not been fully investigated. Nineteen healthy moderately active participants (26.2 ± 1.7 years and BMI: 22.4 ± 2.3 kg·m-2) performed four TTE tests at the second lactate turn point (LTP2) in a double-blind, randomised and placebo-controlled setting consuming either 20, 40 and 60 g·L-1·h-1 of a glucose and fructose combination (CHO20, CHO40 and CHO60) or a placebo (PLA). Glucose [Glu-] and lactate concentrations [La-] as well as ventilatory, heart rate (HR) and rating of perceived exertion (RPE) values were recorded during the tests. There were no statistically significant differences in TTE (PLA: 32.5 ± 9.6 min, CHO20: 35.9 ± 14.5 min, CHO40: 35.1 ± 12.9 min, CHO60: 38.0 ± 17.5 min and p = 0.11). Within each trial arm, no statistically significant differences were found between pre- and post-exercise [Glu-] (p > 0.05). Post-exercise [Glu-] for CHO60 were significantly higher when compared to PLA (p = 0.03). Lastly, mean ventilatory parameters as well as HR and RPE during exercise showed no statistically significant differences between trial arms (p > 0.05). Low-to-moderate amounts of exogenous CHO do not increase TTE in healthy moderately active individuals when compared to a placebo. Therefore, when exercising for less than 60 min at high intensities, exogenous CHO supplementation is not necessary if a CHO rich diet is followed prior to exercise. TRIAL REGISTRATION: DRKS-ID: DRKS00030531.
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