Recruiting

Carbohydrate & Protein

Sponsor:

University of Toronto

Code:

NCT07829237

Conditions

Healthy Adults

Eligibility Criteria

Sex: All

Age: 18 - 35

Healthy Volunteers: Accepted

Interventions

Pre-exercise carbohydrate beverage

Pre-exercise protein beverage

Fasted control beverage

Study Details

Brief summary:

This study will investigate whether pre-exercise nutrition influences sex differences in fuel utilization during endurance exercise. Twenty-four recreationally active adults (12 females and 12 males) will complete three experimental exercise trials in a randomized, counterbalanced crossover design. Before each trial, participants will consume either a carbohydrate beverage, a protein-based beverage, or a flavour-matched non-caloric beverage representing the fasted condition. Thirty minutes later, participants will complete 90 minutes of moderate-intensity cycling followed by a cycling time-to-task-failure test. Whole-body carbohydrate and fat oxidation, exogenous substrate oxidation, blood metabolites, and exercise performance will be assessed.

Conditions

Healthy Adults

Study ID

NCT07829237

Start date

Sep 30, 2026

Status verified date

Sep, 2026

Completion date

Jun 30, 2027

Anticipated

Primary completion date

Jun 30, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 35

Healthy Volunteers: Accepted

Inclusion Criteria:

  • Participating in ≥150 minutes of moderate-to-vigorous physical activity per week
  • VO₂peak classified as "good" or above based on American College of Sports Medicine normative values: >35.0 mL/kg/min for females and >39.0 mL/kg/min for males
  • Body mass index (BMI) between 18 and 27 kg/m²
  • Participating in 3-5 structured exercise sessions per week
  • Weight stable, defined as within ±2 kg for at least 6 months
  • Non-smoker
  • Females must be eumenorrheic

Exclusion Criteria:

  • Polycystic ovarian syndrome (PCOS) or endometriosis Current use of oral contraceptives or oral contraceptive use within the previous 3 months Diagnosed cardiovascular or metabolic disease Hypergonadism or hypogonadism Use of medications for management of blood glucose or lipid metabolism Pregnant or <12 months postpartum Lactating or breastfeeding within 3 months of study commencement Menopausal Recreational tobacco smoking Inability to complete the study exercise protocols or comply with pre-trial dietary or physical activity controls Use of medications that may affect substrate metabolism, including corticosteroids or non-steroidal anti-inflammatory drugs (NSAIDs) Currently following a low-carbohydrate diet, such as a ketogenic or Atkins diet

Study Design

Enrollment

24 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Carbohydrate (CHO)

Participants will consume a carbohydrate beverage following an overnight fast. Thirty minutes after beverage consumption, participants will complete 90 minutes of cycling at 65% of VO2peak, followed by a 2-minute rest and a cycling time-to-task-failure test at 85% of maximal work rate.

experimental: Protein (PRO)

Participants will consume a protein-based beverage following an overnight fast. Thirty minutes after beverage consumption, participants will complete 90 minutes of cycling at 65% of VO2peak, followed by a 2-minute rest and a cycling time-to-task-failure test at 85% of maximal work rate.

placebo comparator: Fasted (FAST)

Participants will remain fasted and consume a non-caloric, flavour-matched beverage. Thirty minutes after beverage consumption, participants will complete 90 minutes of cycling at 65% of VO2peak, followed by a 2-minute rest and a cycling time-to-task-failure test at 85% of maximal work rate.

Interventions

Pre-exercise carbohydrate beverage

A carbohydrate beverage providing 1 g glucose/kg body mass, enriched with 1 mg/kg body mass \[U-13C6\]-D-glucose for assessment of exogenous carbohydrate oxidation, with calorie-free flavouring. The beverage will be consumed within 5 minutes, 30 minutes before exercise.

Pre-exercise protein beverage

A protein-based beverage providing 0.45 g protein/kg body mass and supplemented with 0.24 g fat/kg body mass to match the energy content of the carbohydrate condition. The beverage is enriched with L-\[1-13C\]leucine and flavour-matched to the carbohydrate beverage. It will be consumed within 5 minutes, 30 minutes before exercise.

Fasted control beverage

A non-caloric beverage consisting of water and sugar-free flavouring, flavour-matched to the carbohydrate beverage. The beverage will be consumed within 5 minutes following an overnight fast, 30 minutes before exercise.

Primary outcome measure

  • Whole-body carbohydrate oxidation [ Time Frame: During the 90-minute exercise bout ]
  • Whole-body fat oxidation [ Time Frame: During the 90-min exercise bout ]
  • Exogenous glucose oxidation [ Time Frame: During the 90-min exercise bout ]
  • Exogenous leucine oxidation [ Time Frame: During the 90-min exercise bout ]

Central Contacts and Locations

Central contacts

Jenna Gillen, PhD

4169783244jenna.gillen@utoronto.ca

Victoria Bennett

4169783244victoria.bennett@mail.utoronto.ca

Locations

Goldring Centre for High Performance Sport

Recruiting

Toronto, Ontario, Canada, M5S 2C9

Contacts

Jenna Gillen

4169783244jenna.gillen@utoronto.ca

Victoria Bennett

4169783244victoria.bennett@mail.utoronto.ca

More Information

Sponsor

University of Toronto

Last update posted

Sep 18, 2026

Last verified

Sep, 2026

Keywords

  • exercise metabolism
  • substrate oxidation
  • exercise
  • nutrition
  • protein
  • carbohydrate

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-23. This information was provided to ClinicalTrials.gov by University of Toronto on 2026-09-18.