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

ConditionsExercise Endurance Cycling Performance Carbohydrate Intolerance Sport Nutrition

Trial statusNot yet recruiting

Trial phaseNot applicable

Trial typeInterventional

Biological sexMale

Age18-45

SponsorUniversité de Montréal

About this trial

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.

Eligibility criteria

This trial accepts healthy volunteers

Qualifiers

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.

Disqualifiers

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)

Trial design

Design model

Crossover

Treatments tested in this trial

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 intervention
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/Surgery
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/Surgery
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/Surgery
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 intervention
Immediately post-exercise, a 0-100 mm scale evaluates sweetness, flavor intensity, and overall liking to assess palatability of each drink.
Blinding Integrity
Other intervention
Bang's Blinding Index is calculated from participant guesses of drink identity to confirm whether blinding was successful.

Treatment groups

32 Participants

are divided into 4 treatment groups

Group A: Maple syrup providing 60g of CHO per hourExperimental treatment 12 interventions

Group B: Maple syrup providing 90g of CHO per hourExperimental treatment 12 interventions

Group C: Maple syrup providing 120g of CHO per hourExperimental treatment 12 interventions

Group D: PlaceboPlacebo comparator 12 interventions

Trial outcomes

Primary outcomes

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.

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

Time frame

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

Secondary outcomes

Substrate oxidation rates during exercise

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

Time frame

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

Plasma metabolite concentrations

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.

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).

Ratings of perceived effort during exercise

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.

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)

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

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.

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.

Other outcomes

Hedonic ratings for beverage sweetness, flavor, and liking

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

Time frame

Immediately after time trial completion

Explore correlations between substrate oxidation rates and TT performance.

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

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)

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

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

Time frame

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

Assess gastrointestinal absorption kinetics across maple syrup doses and placebo.

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.

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)

Sponsors and contacts

Click on the lead sponsor to view all of their trials.

Université de Montréal

Lead sponsor

Natural Sciences and Engineering Research Council, Canada

Collaborator

Montreal Heart Institute

Collaborator

Mitacs

Collaborator

Quebec Maple Syrup Producers

Collaborator

Quebec Cycling Federation

Collaborator

Source ClinicalTrials.gov

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