Endurance Trial: Ketone and Carbohydrate Supplementation
Double-Blind Randomized Crossover Trial Examining the Effects of Ketone and Carbohydrate Supplementation on Molecular Biomarkers, Cognitive Function, and Physical Performance in Healthy Endurance Athletes
4 other identifiers
interventional
12
1 country
1
Brief Summary
This randomized, double-blind, crossover study investigates the effects of exogenous ketone supplementation on physical and cognitive performance in amateur endurance athletes during exhaustive exercise. Participants will complete three 3-hour cycling sessions under different nutritional conditions: carbohydrate alone (CHO), carbohydrate plus ketone (CHO-KET), and placebo (PLA). The study will assess cognitive function through validated computerized tests, physical performance via distance covered, and metabolic responses through blood biomarkers. Additionally, peripheral blood mononuclear cells (PBMCs) will be collected and cultured with LPS or not. Other PBMCs co-cultured with neuronal cells (SH-SY5Y) to investigate neuro-immune interactions. The primary hypothesis is that ketone supplementation will preserve cognitive function and enhance physical performance during prolonged exhaustive exercise compared to carbohydrate supplementation alone, potentially through anti-inflammatory mechanisms and alternative energy substrate provision.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at below P25 for not_applicable
Started Dec 2025
Typical duration for not_applicable
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
Study Start
First participant enrolled
December 18, 2025
CompletedFirst Submitted
Initial submission to the registry
May 6, 2026
CompletedFirst Posted
Study publicly available on registry
August 28, 2026
CompletedPrimary Completion
Last participant's last visit for primary outcome
January 1, 2028
ExpectedStudy Completion
Last participant's last visit for all outcomes
January 1, 2029
August 28, 2026
August 1, 2026
2 years
May 6, 2026
August 25, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (5)
Distance covered during the final 20 minutes of maximal effort
Physical performance is assessed as the distance covered during the final 20-minute maximal effort block of each experimental session. Each session begins with 5 minutes of warm-up at 100 W, followed by 155 minutes at 55% of maximal power output (Wmax) with the cycle ergometer set in hyperbolic mode, and ends with 20 minutes of maximal self-paced effort in linear mode. Load is individually prescribed from the maximal incremental test performed at Visit 1. Participants ride the bicycle they are accustomed to, mounted on an electromagnetically braked cycle ergometer, and distance is recorded by the ergometer software. Unit: kilometres
Visits 2, 3 and 4 (weeks 3, 4 and 5): final 20 minutes of exercise.
Visuospatial working memory: Corsi block-tapping span
Visuospatial working memory is assessed with the Corsi block-tapping task from the Psychology Experiment Building Language (PEBL) battery. Sequences of illuminated squares are presented, starting with two blocks and increasing by one every two attempts, until two consecutive errors occur. The span is the length of the longest sequence correctly reproduced; higher values indicate better working memory. Participants are familiarized with the task at Visit 1, and a brief rehearsal is performed immediately before testing at each experimental session. Unit: number of blocks
Visit 1 (week 0), familiarization session. Visits 2, 3 and 4 (weeks 3, 4 and 5): 15 minutes after the standardized breakfast, before the first supplement dose; and 5 minutes after the end of exercise.
Inhibitory control: accuracy on No-Go trials
Inhibitory control is assessed with the Go/No-Go task from the PEBL battery. The letters P or R replace a blue star on screen, with 10 practice trials followed by 160 stimuli per block in an 80:20 Go to No-Go ratio, a 500-millisecond stimulus duration and a 1500-millisecond inter-stimulus interval. Accuracy on No-Go trials is reported as the proportion of correctly withheld responses, ranging from 0 to 1, with higher values indicating better inhibitory control. Unit: proportion of correct responses
Visit 1 (week 0), familiarization session. Visits 2, 3 and 4 (weeks 3, 4 and 5): 15 minutes after the standardized breakfast, before the first supplement dose; and 5 minutes after the end of exercise.
Processing speed: reaction time on Go trials
Reaction time on correct Go trials of the Go/No-Go task described above is recorded automatically by the PEBL software and reported as the mean latency in milliseconds. Lower values indicate faster processing speed.
Visit 1 (week 0), familiarization session. Visits 2, 3 and 4 (weeks 3, 4 and 5): 15 minutes after the standardized breakfast, before the first supplement dose; and 5 minutes after the end of exercise.
Cognitive flexibility: Trail Making Test B minus A completion time
Cognitive flexibility is assessed with the Trail Making Test, parts A and B, from the PEBL battery. In part A the participant selects numbered circles from 1 to 26 in ascending order as fast as possible; in part B the participant alternates between numbers and letters. The difference between the completion times of part B and part A is reported, with lower values indicating greater cognitive flexibility. Unit: milliseconds
Visit 1 (week 0), familiarization session. Visits 2, 3 and 4 (weeks 3, 4 and 5): 15 minutes after the standardized breakfast, before the first supplement dose; and 5 minutes after the end of exercise.
Secondary Outcomes (19)
Gastrointestinal symptom severity
Visits 2, 3 and 4 (weeks 3, 4 and 5): immediately before breakfast; immediately before exercise; 40, 100 and 160 minutes after exercise onset; immediately after exercise; and 60 minutes after exercise.
Serum intestinal fatty acid-binding protein concentration
Visits 2, 3 and 4 (weeks 3, 4 and 5): baseline on arrival after an 8 to 12 hour overnight fast, and 60 minutes after the end of exercise.
Protein expression of kynurenine pathway, endoplasmic reticulum stress, autophagy and oxidative stress markers in PBMCs
Visits 2, 3 and 4 (weeks 3, 4 and 5): baseline on arrival after an 8 to 12 hour overnight fasting, and 60 minutes after the end of exercise.
Sleep difficulty score on the Athlete Sleep Screening Questionnaire
Sleep during the 7 days preceding each assessment. Assessed at Visit 1 (week 0) and at Visits 2, 3 and 4 (weeks 3, 4 and 5). At the experimental sessions the questionnaire is administered immediately after the standardized breakfast.
Fatigue and vigour subscale scores on the Brunel Mood Scale
Visit 1 (week 0). Visits 2, 3 and 4 (weeks 3, 4 and 5): immediately after the baseline cognitive battery, 45 minutes before exercise; and immediately after the post-exercise cognitive battery, 40 minutes after exercise.
- +14 more secondary outcomes
Other Outcomes (1)
Total work produced during the final 20 minutes of maximal effort
Visits 2, 3 and 4 (weeks 3, 4 and 5): final 20 minutes of exercise.
Study Arms (3)
Carbohydrate (CHO)
ACTIVE COMPARATORParticipants receive a non-caloric, flavour-matched placebo before exercise, at 45 and 5 minutes before the start of the cycling protocol, and a carbohydrate beverage during exercise. Interventions administered in this arm: standardized evening meal, standardized breakfast, pre-exercise non-caloric placebo, and carbohydrate beverage.
Placebo (PLA)
PLACEBO COMPARATORParticipants receive a non-caloric, flavour-matched placebo before exercise, at 45 and 5 minutes before the start of the cycling protocol, and a non-caloric placebo beverage during exercise. No carbohydrate and no ketone precursor are provided after the standardized breakfast. Interventions administered in this arm: standardized evening meal, standardized breakfast, pre-exercise non-caloric placebo, and during-exercise non-caloric placebo.
Carbohydrate plus ketone (CHO-KET)
EXPERIMENTALParticipants receive (R)-1,3-butanediol before exercise, at 1.0 g/kg body mass 45 minutes before the start of the cycling protocol and a further 0.5 g/kg 5 minutes before the start, and the same carbohydrate beverage as the CHO arm during exercise. Interventions administered in this arm: standardized evening meal, standardized breakfast, (R)-1,3-butanediol, and carbohydrate beverage.
Interventions
Participants ingest 210 mL of a \~15% carbohydrate solution, providing 30 g of carbohydrate per dose, every 20 minutes from the start of the 155-minute fixed-intensity phase, with the final dose taken immediately before the start of the 20-minute maximal effort block. No beverage is provided during the maximal effort. The solution combines sucrose and dextrose so that glucose and fructose are absorbed through separate intestinal transporters. All doses are supplied in opaque, coded bottles prepared by a researcher not involved in the assessments, so that treatments cannot be identified visually.
Participants ingest (R)-1,3-butanediol at 1.0 g/kg body mass 45 minutes before the start of the cycling protocol and a further 0.5 g/kg 5 minutes before the start, for a total dose of 1.5 g/kg body mass. The dose was selected to sustain blood beta-hydroxybutyrate at approximately 2 mmol/L throughout the session, a range compatible with nutritional ketosis and without risk to participants. Doses are supplied in opaque, coded bottles prepared by a researcher not involved in the assessments.
Participants ingest a non-caloric placebo beverage at 45 and 5 minutes before the start of the cycling protocol, at the same time points at which the (R)-1,3-butanediol is administered in the CHO-KET arm. The placebo is matched to the ketone beverage for volume, appearance and flavour, and provides no energy. Doses are supplied in opaque, coded bottles prepared by a researcher not involved in the assessments.
Participants ingest 210 mL of a non-caloric placebo beverage every 20 minutes from the start of the 155-minute fixed-intensity phase, with the final dose taken immediately before the start of the 20-minute maximal effort block. No beverage is provided during the maximal effort. The placebo is water with the same flavouring used in the carbohydrate beverage, matched for volume, appearance and ingestion schedule, and provides no energy. Doses are supplied in opaque, coded bottles prepared by a researcher not involved in the assessments.
On the evening before each experimental session, participants consume a standardized meal providing 1.5 g of carbohydrate per kg of body mass. The same meal is provided before all three experimental sessions and is followed by an overnight fast of 8 to 12 hours.
Each experimental session comprises 5 minutes of warm-up at 100 W, 155 minutes at 55% of maximal power output (Wmax) with the cycle ergometer set in hyperbolic mode, and a final 20 minutes of maximal self-paced effort in linear mode, followed by 5 minutes of low-load cool-down. The same protocol is applied in all three conditions, with load individually prescribed from the maximal incremental test performed at the pre-experimental visit.
On the morning of each experimental session, after the baseline venous blood draw and following an overnight fast of 8 to 12 hours, participants consume a standardized breakfast providing 1.5 g of carbohydrate per kg of body mass, 40 g of protein and 7 g of fat. Participants are instructed to consume the entire meal. The same breakfast is provided before all three experimental sessions.
Eligibility Criteria
You may qualify if:
- Amateur male cyclists;
- At least 2 years of cycling experience;
- At least 5 hours of endurance cycling training per week;
- VO2max of at least 50 mL/kg/min.
You may not qualify if:
- Confirmed diagnosis of COVID-19 by PCR or rapid antigen test within the last 12 months;
- Symptoms compatible with COVID-19 within the last six months;
- Smokers;
- Alcoholics;
- Presence of neurological, immune, or muscular diseases;
- Use of psychoactive medications in the last year;
- Use of any acute medication prior three days each visit that possible could affect the experiment such as stool-altering medications and non-steroidal anti-inflammatory drugs;
- Confirmed gastrointestinal infections, diseases, or disorders (e.g., coeliac disease, inflammatory bowel disease, irritable bowel syndrome, diverticular disease, gastroesophageal reflux disease);
- Medical history of gastrointestinal surgery, or any other self-reported gastrointestinal issues;
- Within the previous three months, if they had consumed substances that could affect gastrointestinal integrity or followed gastrointestinal-targeted dietary regimes;
- Participants with any food allergy should be excluded of this study.
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (1)
School of Physical Education and Sport of Ribeirão Preto - University of São Paulo
Ribeirão Preto, São Paulo, 14040-900, Brazil
MeSH Terms
Conditions
Interventions
Condition Hierarchy (Ancestors)
Study Officials
- PRINCIPAL INVESTIGATOR
Joao P Floriano
University of Sao Paulo
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- not applicable
- Allocation
- RANDOMIZED
- Masking
- QUADRUPLE
- Who Masked
- PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
- Masking Details
- All supplement doses are prepared by a researcher not involved in the administration of the protocol or in any assessment, and are supplied in opaque, coded bottles matched for volume, appearance and flavour across conditions, so that treatments cannot be identified visually. The randomization sequence is generated and held by a researcher external to the study team. At the end of each session participants are asked which supplement they believe they received, as a manipulation check on blinding.
- Purpose
- BASIC SCIENCE
- Intervention Model
- CROSSOVER
- Sponsor Type
- OTHER
- Responsible Party
- PRINCIPAL INVESTIGATOR
- PI Title
- Professor
Study Record Dates
First Submitted
May 6, 2026
First Posted
August 28, 2026
Study Start
December 18, 2025
Primary Completion (Estimated)
January 1, 2028
Study Completion (Estimated)
January 1, 2029
Last Updated
August 28, 2026
Record last verified: 2026-08
Data Sharing
- IPD Sharing
- Will share
- Shared Documents
- STUDY PROTOCOL, SAP, ICF, CSR
- Time Frame
- Data will be available beginning 6 months after publication of the primary results and will remain available for a period of 5 years. Supporting documents will be available within the same timeframe.
- Access Criteria
- Access will be granted to qualified researchers who provide a methodologically sound research proposal. Requests must include study objectives, analysis plan, and evidence of institutional affiliation. Data will be shared under a data use agreement that prohibits re-identification of participants and limits use to the approved research purposes. Requests should be directed to the principal investigator. Data will be provided in a de-identified format via secure data transfer
De-identified individual participant data (IPD) underlying the results reported in this study will be shared. This includes metabolic variables (e.g., blood lactate, glucose, ketone concentrations), physiological responses (e.g., VO₂, VCO₂, heart rate), performance outcomes, perceptual measures (RPE and gastrointestinal symptoms), and cognitive test results. All data will be fully anonymized, with removal of direct and indirect identifiers, ensuring that participants cannot be re-identified. Data dictionaries and variable descriptions will be provided to facilitate interpretation and reuse.