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NCT Number: NCT07063732

Ketone Monoester Supplements, High Altitude, and Brain Blood Flow During Exercise

The purpose of this trial is to investigate the effect of acute ketone monoester ingestion (0.6 g KME/kg body weight) on the occurrence of the ventilatory threshold and the subsequent response of blood velocity in cerebral arteries during a maximal exercise test at low altitude and high altitude.

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Key information

Conditions

High Altitude Hypoxia Behavior Exercise Motor Activity

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Guelph, Guelph, Ontario, Canada

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Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Must be a member of the research expedition team travelling to the Barcroft Research Station in White Mountain California

Exclusion criteria

  • BMI > 30
  • No prescribed medications (oral contraceptives excluded)
  • History of smoking
  • Currently following a ketogenic diet or consuming exogenous ketogenic supplements
  • History of heart, lung, blood vessel, or kidney disease
  • Currently pregnant

Treatment and study plan

Ketone Monoester (KME)

Dietary Supplement

0.6 g KME per kg body mass; [R]-3-hydroxybutyl [R]-3-hydroxybutyrate. (Delta G Ketone, TΔS, Oxford).

Placebo

Dietary Supplement

Inert, calorie-free placebo drink that is taste-matched to the ketone monoester supplement

Primary outcomes

  1. Cerebral Blood Velocity

    Time frame: 3 hours

    Transcranial Doppler ultrasound will be used to measure blood velocity in the middle cerebral artery and posterior cerebral artery. Location of measurements will remain consistent within participants.

Secondary outcomes

  1. Cardiac Output

    Time frame: 3 hours

    Cardiac output (L/min) will be measured using a non-invasive cardiac output monitor (Physioflow). The monitor uses signal morphology impedance cardiography to determine cardiac output.

  2. Blood Pressure

    Time frame: 3 hours

    Mean arterial pressure (mmHg) will be measured via a brachial cuff placed on the upper arm.

  3. Ventilatory Threshold

    Time frame: 3 hours

    Ventilatory threshold (VT) will be calculated based on previously described methods (Gaskill et al., 2001).

  4. End-Tidal Gases

    Time frame: 3 hours

    End-tidal oxygen (PETO2) (mmHg) and carbon dioxide (PETCO2) (mmHg) will be collected using a metabolic cart.

  5. Rate of Oxygen Consumption and Carbon Dioxide Production

    Time frame: 3 hours

    Rate of oxygen consumption (VO2) (mL/min) and carbon dioxide production (VCO2) (mL/min) will be collected using a metabolic cart.

  6. Ventilation

    Time frame: 3 hours

    Ventilation (Ve) (L/min) will be collected using a metabolic cart.

  7. Blood Lactate and Beta-Hydroxybutyrate

    Time frame: 3 hours

    Capillary blood will be obtained via finger prick using a lancing device to measure concentrations of blood lactate (mmol/L) and beta-hydroxybutyrate (mmol/L) using a handheld metabolite analyzer.

  8. Peak Work Rate (Maximal Exercise Test)

    Time frame: 3 hours

    The maximum wattage (W) achieved by the participant during the maximal exercise test will be recorded.

Sponsors and collaborators

Lead sponsor

McMaster University

Other

Registry information

Official study title

The Effect of Ketone Monoester Supplementation and High Altitude on Exercising Cerebral Blood Flow

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Jul 14, 2025
Registry last updated
Jul 14, 2025

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

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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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