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NCT Number: NCT07389837

Maple Syrup Carbohydrate Dose-Response on 20-km Cycling Time-Trial Performance

The goal of this clinical trial is to learn whether maple syrup can be used as a natural carbohydrate source to help trained male cyclists perform better during long-duration cycling. The study also aims to learn how different amounts of maple syrup affect energy use in the body, stomach comfort, and feelings of effort and fatigue.

The main questions the study aims to answer are:

* Does consuming more carbohydrate from maple syrup help participants finish a 20-kilometer cycling time trial faster? * How do different amounts of maple syrup change how the body uses carbohydrates and fats during long exercise? * Are higher amounts of maple syrup easy for participants to tolerate without stomach problems?

Researchers will compare four drinks:

1. A placebo drink (a look-alike drink with no calories), 2. A drink that provides 60 grams of carbohydrate per hour, 3. A drink that provides 90 grams per hour, and 4. A drink that provides 120 grams per hour.

They will compare these drinks to see whether higher carbohydrate amounts lead to better cycling performance and how each dose affects comfort and metabolism.

Participants will:

* Attend a screening visit that includes a health check and a glucose tolerance test. * Complete a fitness test to measure their aerobic capacity and practice the cycling tests used in the study. * Take part in four separate exercise sessions in random order. Each session includes: * Drinking one of the four study beverages during 2 hours of steady cycling, * Completing two short, all-out 6-second sprints during the ride, * Completing a 20-kilometer cycling time trial as fast as possible, * Reporting stomach symptoms and perceptions of effort, * Providing breath, blood, urine, and sweat samples so researchers can measure how their body uses fuel.

All drinks will look, taste, and smell similar so participants cannot tell which one they are receiving. Meals before each session will be provided to keep conditions the same across visits.

This study may help athletes and active people choose natural carbohydrate sources that support both performance and comfort during long endurance exercise. The findings may also guide future research on the use of maple syrup as a sports nutrition option.

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Key information

Conditions

Exercise Behavior Carbohydrate Intolerance Endurance Cycling Performance Glucose-Galactose Malabsorption Motor Activity Sport Nutrition

Age range

18 year–45 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age: 18-45 years.
  • Relative VO2max: >55 mL·min-¹·kg-¹ for level 3; >65 mL·min-¹·kg-¹ for level 4.
  • Peak Power Output (PPO): >4.6 W·kg-¹ (absolute PPO >320 W).
  • Training History: >5 hours/week of cycling-specific training; >1 year of consistent endurance training.
  • No history of metabolic disorders, gastrointestinal issues, or contraindications to exercise testing.

Exclusion criteria

  • Current or past metabolic disorders (diabetes, metabolic syndrome)
  • Cardiovascular disease or abnormal ECG at rest
  • Gastrointestinal disorders (IBS, Crohn's, celiac disease)
  • Food allergies or intolerances (particularly maple, fructose)
  • Current use of medications affecting metabolism
  • Smoking or nicotine use
  • Alcohol consumption >14 units/week
  • Recent illness or injury (<4 weeks)
  • Participation in other clinical trials (<3 months)
  • Unable to maintain consistent training during study period

Treatment and study plan

Maple Syrup Beverages

Dietary Supplement

Pure maple syrup is diluted in water and mixed with electrolytes (sodium, potassium, magnesium) to resemble a sports drink. Participants receive one of three carbohydrate doses (60, 90, or 120 g per hour). Drinks are ingested every 15 minutes during 120 minutes of cycling, for a total of ~750 mL per hour. All doses have the same volume, temperature, electrolyte content, and schedule.

Placebo Beverage

Dietary Supplement

Participants receive a calorie-free electrolyte drink designed to mimic maple syrup. Sotolon (maple aroma) and stevia are added in small amounts to reproduce sweetness, flavor, and smell without providing energy. The drink is administered in identical volumes and timing to the maple syrup beverages (~750 mL per hour, every 15 minutes).

Pre-Trial Meals

Other

To control nutrition before each trial, participants are provided with a standardized dinner the night before and a standardized breakfast 2-3 hours before testing. Meals contain the same calories and macronutrient distribution across all sessions. Participants must also replicate their training during the previous 48 hours.

D₂O Fluid Absorption

Procedure

At 30 minutes of cycling, participants ingest a small, safe dose of deuterium oxide (7-8 mL) to measure fluid absorption and gastric emptying. Additional blood samples are collected at +32, +35, and +40 minutes to capture early absorption. Urine is collected to measure deuterium enrichment and validate absorption kinetics.

Time Trial Performance

Behavioral

After 120 minutes of steady cycling, participants complete a 20-km self-paced time trial. Only distance is displayed. The primary outcome is completion time; mean power is analyzed as supportive information.

Substrate Oxidation

Procedure

Energy metabolism is measured using indirect calorimetry and ¹³C-sucrose breath enrichment. Samples are collected at rest and every 30 minutes during exercise to quantify carbohydrate and fat use, distinguishing ingested vs. stored carbohydrate oxidation. Urine and sweat correct protein oxidation.

Blood Metabolites

Procedure

Blood samples collected every 30 minutes measure glucose, insulin, lactate, and fatty acids. Samples are stored for later analysis of hormonal and metabolic responses.

Gastrointestinal Symptoms

Diagnostic Test

Participants rate stomach symptoms (0-10 scale) before exercise, every 30 minutes during cycling, and after the time trial. Scores quantify total, upper, and lower GI discomfort.

Perceptual Responses

Diagnostic Test

Effort and muscle pain are assessed using the Borg CR100 scale during exercise and throughout the time trial at preset intervals.

Neuromuscular Fatigue

Diagnostic Test

Participants perform two 6-second maximal sprints at baseline, 60 and 120 minutes of cycling, and after the time trial. Peak power, cadence, and torque assess fatigue progression and recovery.

Hedonic Ratings

Other

Immediately post-exercise, a 0-100 mm scale evaluates sweetness, flavor intensity, and overall liking to assess palatability of each drink.

Blinding Integrity

Other

Bang's Blinding Index is calculated from participant guesses of drink identity to confirm whether blinding was successful.

Primary outcomes

  1. Assess the dose-response effect of maple syrup carbohydrate ingestion (0, 60, 90, 120 g·h-¹) on 20-km cycling time-trial performance in trained male cyclists.

    Time frame: Immediately after completion of the 20-km time trial during each experimental visit

    20-km time trial completion time (minutes), measured at the end of each experimental visit.

Secondary outcomes

  1. Substrate oxidation rates during exercise

    Time frame: At rest, immediately before exercise, and every 30 minutes during 120 minutes of constant-load cycling

    Exogenous and endogenous carbohydrate oxidation, fat oxidation, and protein oxidation rates (g·min-¹) measured via ¹³C stable isotope breath enrichment and indirect calorimetry.

  2. Plasma metabolite concentrations

    Time frame: Measured before beverage ingestion, immediately pre-exercise, every 30 minutes during the 120-minute constant-load cycling, and immediately post-exercise (before the time trial).

    Plasma glucose, insulin, lactate, and free fatty acid concentrations sampled before beverage ingestion, pre-exercise, every 30 minutes during constant-load exercise, and immediately after.

  3. Ratings of perceived effort during exercise

    Time frame: Assessed 3 minutes after exercise begins; every 30 minutes during the constant-load cycling (30, 60, 90, 120 min); and at approximately 126, 127, 130, 136, and 145 minutes (corresponding to 0.5, 5, 10, 15, and 20 km during the time trial)

    Ratings of perceived effort (CR100 scale, 0-100) collected after 3 minutes and every 30 minutes during constant-load exercise, and during the time trial.

  4. Assess gastrointestinal tolerance and symptoms across maple syrup doses and placebo.

    Time frame: Measured pre-exercise; every 30 minutes during the 120-minute constant-load cycling (30, 60, 90, 120 min); and immediately after the time trial.

    Gastrointestinal distress scores (0-10 on a modified visual analog scale, mVAS), rated pre-exercise, every 30 minutes during the constant-load exercise, and post-TT; includes composite scores for total, upper, and lower GI symptoms.

  5. Peak power output during maximal sprints

    Time frame: Baseline, 60 minutes, 120 minutes, and immediately after time trial

    Peak power output (watts) from two 6-second maximal sprints performed at baseline, 60 minutes, 120 minutes, and post-time trial.

  6. Mean power output during 20-km time trial

    Time frame: Approximately 25-30 minutes (continuously recorded during the 20-km time trial)

    Mean power output (watts) recorded continuously during the 20-km time trial.

Other outcomes

  1. Hedonic ratings for beverage sweetness, flavor, and liking

    Time frame: Immediately after time trial completion

    Hedonic ratings for sweetness, flavor intensity, and overall liking (0-100 mm visual analog scale) assessed immediately post-exercise.

  2. Explore correlations between substrate oxidation rates and TT performance.

    Time frame: Evaluated using oxidation values measured during cycling (at rest, pre-exercise, and at 30, 60, 90, 120 min) and TT performance measured at approximately 150-155 minutes (immediately after time trial completion)

    Correlation coefficients (e.g., Pearson's r) between exogenous/endogenous oxidation rates and TT time to completion or mean power output.

  3. Examine inter-individual variability in dose-response patterns for performance outcomes.

    Time frame: Calculated from repeated TT measurements collected at each of 4 experimental visits over approximately 4-6 weeks

    Within-subject and inter-individual coefficients of variation for TT time to completion and mean power output across doses.

  4. Assess gastrointestinal absorption kinetics across maple syrup doses and placebo.

    Time frame: Measured via plasma samples at baseline, 30 min (pre-ingestion), and at +32, +35, +40 min, then every 30 min during cycling (60, 90, 120 min), plus within 30 minutes after time trial completion (approximately 150-180 min)

    Deuterium oxide (D2O) tracer kinetics, including absorption rate constant, time-to-peak plasma enrichment (tmax), and area under the curve (AUC), derived from plasma and urine D/H enrichment samples.

  5. Explore whether individual characteristics (e.g., body weight, training volume) moderate the dose-response effects of maple syrup on endurance performance.

    Time frame: Moderation assessed using TT outcomes collected at each of 4 experimental visits over approximately 4-8 weeks, combined with participant baseline characteristics collected at screening visit

    Moderation analysis using interaction terms in linear mixed-effects models (e.g., carbohydrate dose × body weight) for TT time to completion.

  6. Explore plasma metabolomic signatures associated with carbohydrate dose and performance.

    Time frame: Baseline (before beverage ingestion), immediately before exercise, at 60 minutes of constant-load cycling, pre-TT (~125 minutes after beginning constand-load cycling), and post-TT (~150-160 minutes).

    Untargeted metabolomic profiling via high-resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS) on plasma samples collected at before beverage ingestion, before the start of exercise, at 60 minutes into constant-load exercise, pre- and post-TT; focuses on pathways such as glycolysis, lipid oxidation, and amino acid metabolism.

Study contacts

Contact information is provided by the study sponsor or research team.

Philippe Parent, BSc

CONTACT

[email protected]

+1-438-393-9720

Sponsors and collaborators

Lead sponsor

Université de Montréal

Other

Collaborators

  • Mitacs
  • Montreal Heart Institute
  • Natural Sciences and Engineering Research Council, Canada
  • Quebec Cycling Federation
  • Quebec Maple Syrup Producers

Registry information

Official study title

Dose-Response Effects of Maple Syrup Carbohydrate Ingestion (60, 90, 120 g/h) on 20-km Cycling Time-Trial Performance, Substrate Oxidation, and Perceptual Responses in Trained Male Cyclists

Acronym: MAPLE-DR

Important dates

Study start
2026
Primary completion
2026
Study completion
2027
First posted
Feb 5, 2026
Registry last updated
Feb 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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