The Effects of Acute Ketone Monoester Supplementation on Exercise Efficiency and the Influence of Dose and Intensity

Diet can alter blood ketone levels and this in turn may affect exercise capacity. This study will determine if the acute ingestion of a ketone supplement alters cycling exercise efficiency. Participants will perform three trials in a randomized order. Each trial will involve an incremental exercise protocol on a stationary cycle ergometer to volitional fatigue. Participants will ingest either a high or low dose of a ketone supplement or a taste-matched placebo drink prior to exercise. Blood samples will be obtained to assess selected metabolic responses. This study will provide information regarding the effect of ketone supplementation on exercise efficiency.

Inclusion Criteria:Be habitually consuming ≥50 g/d of carbohydrate (i.e., not following a ketogenic diet).Be engaged in endurance-type exercise >3h/wk.Have an estimated VO2peak of ≥90% for age and sex as estimated by an online calculator found at www.worldfitnesslevel.org.Exclusion Criteria:Experiencing a condition that might preclude safe participation in physical activity and exercise, as determined by answering "Yes" to any question on Page 1 of the Canadian Society for Exercise Physiology Get Active Questionnaire.