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

Official 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

Overview

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.

Interventions

• Dietary supplement Maple Syrup Beverages
  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.
• Dietary supplement placebo beverage
  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).
• Other Pre-Trial Meals
  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.
• Procedure D₂O Fluid Absorption
  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.
• Behavioral Time Trial Performance
  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.
• Procedure Substrate Oxidation
  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.
• Procedure Blood Metabolites
  Blood samples collected every 30 minutes measure glucose, insulin, lactate, and fatty acids. Samples are stored for later analysis of hormonal and metabolic responses.
• Diagnostic test Gastrointestinal Symptoms
  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.
• Diagnostic test Perceptual Responses
  Effort and muscle pain are assessed using the Borg CR100 scale during exercise and throughout the time trial at preset intervals.
• Diagnostic test Neuromuscular Fatigue
  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.

Primary outcome measures

• 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]

Secondary outcome measures (6)

• Substrate oxidation rates during exercise [Time frame: At rest, immediately before exercise, and every 30 minutes during 120 minutes of constant-load cycling]
• 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).]
• 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)]
• 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.]
• Peak power output during maximal sprints [Time frame: Baseline, 60 minutes, 120 minutes, and immediately after time trial]
• Mean power output during 20-km time trial [Time frame: Approximately 25-30 minutes (continuously recorded during the 20-km time trial)]

Eligibility criteria

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Double blind

Primary purpose

Basic science

Study locations

Canada · 1 center

• Centre EPIC — Montreal

Publications

• Cermak NM, van Loon LJ. The use of carbohydrates during exercise as an ergogenic aid. Sports Med. 2013 Nov;43(11):1139-55. doi: 10.1007/s40279-013-0079-0. PMID 23846824
• Stellingwerff T, Cox GR. Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Appl Physiol Nutr Metab. 2014 Sep;39(9):998-1011. doi: 10.1139/apnm-2014-0027. Epub 2014 Mar 25. PMID 24951297
• Jeukendrup AE. Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Curr Opin Clin Nutr Metab Care. 2010 Jul;13(4):452-7. doi: 10.1097/MCO.0b013e328339de9f. PMID 20574242
• Vandenbogaerde TJ, Hopkins WG. Effects of acute carbohydrate supplementation on endurance performance: a meta-analysis. Sports Med. 2011 Sep 1;41(9):773-92. doi: 10.2165/11590520-000000000-00000. PMID 21846165
• Smith JW, Zachwieja JJ, Peronnet F, Passe DH, Massicotte D, Lavoie C, Pascoe DD. Fuel selection and cycling endurance performance with ingestion of [13C]glucose: evidence for a carbohydrate dose response. J Appl Physiol (1985). 2010 Jun;108(6):1520-9. doi: 10.1152/japplphysiol.91394.2008. Epub 2010 Mar 18. PMID 20299609
• Hearris MA, Pugh JN, Langan-Evans C, Mann SJ, Burke L, Stellingwerff T, Gonzalez JT, Morton JP. 13C-glucose-fructose labeling reveals comparable exogenous CHO oxidation during exercise when consuming 120 g/h in fluid, gel, jelly chew, or coingestion. J Appl Physiol (1985). 2022 Jun 1;132(6):1394-1406. doi: 10.1152/japplphysiol.00091.2022. Epub 2022 Apr 21. PMID 35446596
• Lavoie L, Tremblay J. Ingestion of maple-based and other carbohydrate sports drinks: effect on sensory perceptions during prolonged exercise. J Int Soc Sports Nutr. 2020 Dec 9;17(1):63. doi: 10.1186/s12970-020-00384-3. PMID 33298104
• De Pauw K, Roelands B, Cheung SS, de Geus B, Rietjens G, Meeusen R. Guidelines to classify subject groups in sport-science research. Int J Sports Physiol Perform. 2013 Mar;8(2):111-22. doi: 10.1123/ijspp.8.2.111. PMID 23428482

Identifiers

NCT: NCT07389837 · ICM 2026-3568

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗