Exogenous KetosisNCT06965491
The Effects of Exogenous Ketosis on Ultra-endurance Recovery and Performance
A study testing Ketone ester supplement in people with Exogenous Ketosis and Endurance Cycling Performance, run by KU Leuven at 1 site in Belgium.
Trial summary
The study aims to investigate the effects of post-exercise and pre-sleep ketosis via oral ketone ester supplementation on physical and mental recovery during a multi-day cycling stage race. Read more about this study
- Who is it for?
- Ages 18 to 59 yearsHealthy volunteers can take part
- Conditions the study is for
- Exogenous Ketosis, Endurance Cycling Performance, Fatigue; Muscle, Heart
- What is being tested?
- Ketone ester supplement
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 18 participants
- Where
- 1 siteBelgium
- Study dates
- 1 Mar 2024to 30 Oct 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 59 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- have been cycling consistently for at least 1 year before entry into the study
- have been cycling for a minimum of 7 hours per week for the 6 months leading up to the study
- additional for the field study: valid entry to the 2025 edition of the Absa Cape Epic
- non-smoker
Who cannot join
- Do not follow a ketogenic diet or low-carbohydrate diet
- Have any metabolic or auto-immune disease that will influence their metabolism
- Take medication or supplements that is known to affect ketone supplement metabolism
- suffering from a recurring injury or illness from which they have not fully recovered that is a contr-indication to perform high-intensity exercise
- Unable to finish each stage
- Women: if they are pregnant or breastfeeding
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Exploring the Role of Intermittent Exogenous Ketosis on Physical and Mental Fatigue During Ultra-endurance Performance
The study aims to investigate the effects of post-exercise and pre-sleep ketosis via oral ketone ester supplementation on physical and mental recovery during a multi-day cycling stage race.
Read the detailed description
Ultra-endurance events are becoming increasing popular. Participation in the multi-day events adds a lot of physical and mental strain on the body, while the athletes are still required to perform. Without appropriate recovery the athletes are at increased risk of overreaching, injury, or illness.
Therefore, the purpose of the study is to create a better understanding of the exercise fatigue experienced during ultra-endurance performance and the role intermittent exogenous ketosis (IEK) plays in reducing the amount of fatigue to maintain performance during multi-day racing and lower the risk of injury and illness.
Participants will first compete in a 8-day simulated stage race performed on taxc trainers and then we will conduct a field study during the Absa Cape Epic a 8-day mountain bike stage race. Immediately following each stage and 30-mins before bed the participants will consume either a ketone ester and taste-match placebo drink. During the race the following variables will be measured; hydration status, weight change, activity readiness, and nutrition intake. Cognitive function will be assessed on day 2, 4 and 8 of racing. One day before and one day after the race the participants will report to the lab to assess basal metabolic rate, stress via questionnaires, appetite, cognitive function, muscle biopsies, venous blood samples, mechanical efficiency and 30-min Time Trial.
- Being tested
- Placebo Supplement, Ketone ester supplement
- Keywords
- ultra-endurance, cycling, physiological strain, mental fatigue
- Medical subject headings
- Fatigue, Mental Fatigue
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Placebo SupplementDietary supplement
Placebo supplement:
Oral supplement containing: 16.4 grams of medium chained triglycerides, 1mM or sucrose octaacetate and water
Ketone ester supplementDietary supplement
Ketone ester supplement Oral supplement containing: 25 grams of pure (R)-3-hydroxybutyl-(R)-3-hydroxybutyrate ketone monoester drink
| Study group | Role | What they receive |
|---|---|---|
| Control group | Placebo comparator | Intervention: 8-day multistage mountain bike race/simulation Dietary intervention: placebo supplement (oral supplement containing: 16.4 grams of medium chained triglycerides, 1mM of sucrose octaacetate and water) Receives: Dietary Supplement: Placebo Supplement |
| Experimental group | Experimental | Intervention: 8-day multistage mountain bike race/simulation Dietary intervention: ketone ester supplement (25 grams of pure R-(3)-hydroxybutyl-(R)-3-hydroxybutyrate ketone monoester drink) Receives: Dietary Supplement: Ketone ester supplement |
What is being measured
The primary outcome is the main question the study is designed to answer.
Muscle soreness
Visual analog scale (0-10) How sore does you leg muscles feel? The VAS was used as a subjective measure of muscle soreness
Measured: During the intervention
Physical stress
RESTQ-76 sport questionnaire was used to assess the stress-recovery balance
Measured: pre-intervention and 1 day after the intervention
Hydration status
Before every stage, the participants provided a urine sample in a cup. A urine-specific refractometer (Atago) was used to determine their hydration status
Measured: Baseline, During the intervention and 1 day after the intervention
Cognitive function: reaction time
CANTAB test battery reaction time test was used to determine reaction time in milliseconds.
Measured: Pre-intervention, day 2, 4 and 8 of the intervention
Cognitive function: rapid visual processing
CANTAB test battery rapid visual processing test was used to assess their susceptibility to false alarms
Measured: Pre-intervention, day 2, 4 and 8 of the intervention
Cognitive function: swm
CANTAB spatial working memory test was used to access executive function; the main outcome measure used was the number of errors
Measured: Pre-intervention, day 2, 4 and 8 of the intervention
Sleep Duration
Fitbit inspire 3 was used to measure sleep duration (hours:minutes:seconds)
Measured: 1 week prior to racing and during the race
Sleep: REM
The Fitbit Inspire 3 was used to measure the total duration of rapid eye motion (REM)sleep during each night for the duration of the study. The REM sleep phase will be analysed in minutes
Measured: 1 week prior to racing and during the race
Sleep: Non-REM
The Fitbit Inspire 3 will be used to determine the NON-REM sleep phase for each night in minutes
Measured: 1 week prior to racing and during the race
Sleep: WASO
The FITBIT inspire 3 will be used to measure wake after sleep onset in minutes for each night
Measured: 1 week prior to racing and during the race
Secondary outcomes (7)
Mechanical efficiency
Mechanical efficiency will be determined during three constant load (100 watts, 150 watts, and 200 watts) cycling bouts of 5 minutes on a calibrated ergometer (Avantronic Cyclus II). Throughout the test, gas exchange will continuously be measured using calibrated metabolic analyzer with a face mask (Cortex, Metalyzer IIIb). VO2 and VCO2 data of the final minute of each workload will be used to calculate gross efficiency (%).
Measured: pre-intervention and 1 day after the intervention
Time trial performance
The participants will perform a 30-minute time trial. The average power output (watts) achieved will be used as the outcome measure.
Measured: pre-intervention and 1 day after the intervention
Appetite
Appetite will be assessed with a Likert visual analog scale (0-10) using the following four questions:
"How hungry do you feel?" "How full do you feel?" "How satisfied do you feel?" "How much do you think you could eat now?"
Measured: pre-intervention, during the intervention, 1 day after the intervention
Macronutrient intake
Participants will complete a food diary using the Mijnetemeter application on their phone. Total fat, protein and carbohydrate intake will be determined in grams for each day.
Measured: baseline, during the intervention
Total energy intake
Participants will complete a food diary, using the Mijnetemeter application on their phones. total energy intake (kilojoules) will be calculated for each day.
Measured: baseline, during the intervention
Racing intensity
hear rate zones during racing
Measured: during each stage
Body weight change
Body mass was measured using a SECA, model 813 electrical scale, before and after each stage as a secondary method to assess hydration status. Body mass was measured to the nearest 0.1 kilogram
Measured: During the intervention
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 May 2025
- Study start1 Mar 2024
- Primary completion27 Mar 2025
- Study completion30 Oct 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Exogenous KetosisStudies of the same condition, open and under way.
- More trials run by KU LeuvenThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Riders will be paired matched and randomly assigned to either the ketone ester supplementation (KE) group or the control group (CON) which will receive an isocaloric taste-matched placebo
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 18 participants (actual)
Sponsor and investigators
- Lead sponsor
- KU Leuven
- Sponsor type
- University, hospital or other
- Collaborators
- University of Stellenbosch
- Responsible party
- Principal investigator, Chiel Poffé, KU Leuven
- Investigators
- Chiel Poffé, Principal investigator, KU Leuven
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06965491
- Sponsor's protocol ID
- S68178
- Status last verified
- May 2025
- First submitted
- 4 Oct 2024
- Last updated
- 20 Feb 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 20 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Exploring the Role of Intermittent Exogenous Ketosis on Physical and Mental Fatigue During Ultra-endurance Performance
- ClinicalTrials.gov ID
- NCT06965491
- Acronym / sponsor ID
- S68178
- Keywords
- ultra-endurance, cycling, physiological strain, mental fatigue
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 18 participants (actual)
- Lead sponsor
- KU LeuvenUniversity, hospital or other
- Collaborators
- University of Stellenbosch
- Study start
- 1 Mar 2024 (actual)
- Primary completion
- 27 Mar 2025 (actual)
- Study completion
- 30 Oct 2025 (actual)
- First posted
- 11 May 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The study aims to investigate the effects of post-exercise and pre-sleep ketosis via oral ketone ester supplementation on physical and mental recovery during a multi-day cycling stage race.
Detailed description
Ultra-endurance events are becoming increasing popular. Participation in the multi-day events adds a lot of physical and mental strain on the body, while the athletes are still required to perform. Without appropriate recovery the athletes are at increased risk of overreaching, injury, or illness.
Therefore, the purpose of the study is to create a better understanding of the exercise fatigue experienced during ultra-endurance performance and the role intermittent exogenous ketosis (IEK) plays in reducing the amount of fatigue to maintain performance during multi-day racing and lower the risk of injury and illness.
Participants will first compete in a 8-day simulated stage race performed on taxc trainers and then we will conduct a field study during the Absa Cape Epic a 8-day mountain bike stage race. Immediately following each stage and 30-mins before bed the participants will consume either a ketone ester and taste-match placebo drink. During the race the following variables will be measured; hydration status, weight change, activity readiness, and nutrition intake. Cognitive function will be assessed on day 2, 4 and 8 of racing. One day before and one day after the race the participants will report to the lab to assess basal metabolic rate, stress via questionnaires, appetite, cognitive function, muscle biopsies, venous blood samples, mechanical efficiency and 30-min Time Trial.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
- Model description
- Riders will be paired matched and randomly assigned to either the ketone ester supplementation (KE) group or the control group (CON) which will receive an isocaloric taste-matched placebo
| Arm | Type | Receives |
|---|---|---|
| Control group | Placebo comparator | Dietary Supplement: Placebo SupplementIntervention: 8-day multistage mountain bike race/simulation Dietary intervention: placebo supplement (oral supplement containing: 16.4 grams of medium chained triglycerides, 1mM of sucrose octaacetate and water) |
| Experimental group | Experimental | Dietary Supplement: Ketone ester supplementIntervention: 8-day multistage mountain bike race/simulation Dietary intervention: ketone ester supplement (25 grams of pure R-(3)-hydroxybutyl-(R)-3-hydroxybutyrate ketone monoester drink) |
Who may qualify
- Ages
- 18 to 59 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- have been cycling consistently for at least 1 year before entry into the study
- have been cycling for a minimum of 7 hours per week for the 6 months leading up to the study
- additional for the field study: valid entry to the 2025 edition of the Absa Cape Epic
- non-smoker
Key exclusion criteria (6 listed)
- Do not follow a ketogenic diet or low-carbohydrate diet
- Have any metabolic or auto-immune disease that will influence their metabolism
- Take medication or supplements that is known to affect ketone supplement metabolism
- suffering from a recurring injury or illness from which they have not fully recovered that is a contr-indication to perform high-intensity exercise
- Unable to finish each stage
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Placebo SupplementPlacebo supplement: Oral supplement containing: 16.4 grams of medium chained triglycerides, 1mM or sucrose octaacetate and water | Dietary supplement | Control group |
| Ketone ester supplementKetone ester supplement Oral supplement containing: 25 grams of pure (R)-3-hydroxybutyl-(R)-3-hydroxybutyrate ketone monoester drink | Dietary supplement | Experimental group |
Primary outcome
Muscle soreness
Time frame: During the intervention
Visual analog scale (0-10) How sore does you leg muscles feel? The VAS was used as a subjective measure of muscle soreness
Physical stress
Time frame: pre-intervention and 1 day after the intervention
RESTQ-76 sport questionnaire was used to assess the stress-recovery balance
Hydration status
Time frame: Baseline, During the intervention and 1 day after the intervention
Before every stage, the participants provided a urine sample in a cup. A urine-specific refractometer (Atago) was used to determine their hydration status
Cognitive function: reaction time
Time frame: Pre-intervention, day 2, 4 and 8 of the intervention
CANTAB test battery reaction time test was used to determine reaction time in milliseconds.
Cognitive function: rapid visual processing
Time frame: Pre-intervention, day 2, 4 and 8 of the intervention
CANTAB test battery rapid visual processing test was used to assess their susceptibility to false alarms
Cognitive function: swm
Time frame: Pre-intervention, day 2, 4 and 8 of the intervention
CANTAB spatial working memory test was used to access executive function; the main outcome measure used was the number of errors
Sleep Duration
Time frame: 1 week prior to racing and during the race
Fitbit inspire 3 was used to measure sleep duration (hours:minutes:seconds)
Sleep: REM
Time frame: 1 week prior to racing and during the race
The Fitbit Inspire 3 was used to measure the total duration of rapid eye motion (REM)sleep during each night for the duration of the study. The REM sleep phase will be analysed in minutes
Sleep: Non-REM
Time frame: 1 week prior to racing and during the race
The Fitbit Inspire 3 will be used to determine the NON-REM sleep phase for each night in minutes
Sleep: WASO
Time frame: 1 week prior to racing and during the race
The FITBIT inspire 3 will be used to measure wake after sleep onset in minutes for each night
7 secondary outcomes
Mechanical efficiency
Time frame: pre-intervention and 1 day after the intervention
Time trial performance
Time frame: pre-intervention and 1 day after the intervention
Appetite
Time frame: pre-intervention, during the intervention, 1 day after the intervention
Macronutrient intake
Time frame: baseline, during the intervention
Total energy intake
Time frame: baseline, during the intervention
Racing intensity
Time frame: during each stage
Body weight change
Time frame: During the intervention
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 Feb 2026.
Related trials for Exogenous Ketosis
Not yet recruitingEarly Phase 1
The Effects of Ketone Supplements With Carbohydrates on Cycling Performance Above Lactate Threshold
Exogenous Ketosis
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Chiel Poffé principal investigator
KU Leuven
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Ketone ester supplement in people with Exogenous Ketosis and Endurance Cycling Performance, run by KU Leuven at 1 site in Belgium.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 20 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Belgium. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Muscle soreness (time frame: During the intervention). The study lists 10 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 Feb 2026; AzTrials last refreshed its copy on 8 Nov 2026.