# Effect of Low‐To‐Moderate Exogenous Carbohydrate Supplementation on Time to Exhaustion During Constant Load Intense Cycling in Healthy Individuals. A Double‐Blind, Randomised and Placebo‐Controlled Crossover Trial

## TL;DR

This study found that low-to-moderate carbohydrate supplementation during intense cycling does not significantly improve endurance in healthy individuals.

## Contribution

The study provides new evidence that low-to-moderate exogenous carbohydrate intake does not enhance time to exhaustion in moderately active individuals.

## Key findings

- No significant differences in time to exhaustion were observed between placebo and carbohydrate supplementation groups.
- Post-exercise glucose levels were significantly higher in the highest carbohydrate group compared to placebo.
- Ventilatory, heart rate, and perceived exertion measures did not differ significantly between groups.

## 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.

DRKS‐ID: DRKS00030531