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

This study will determine if the acute ingestion of a ketone supplement alters cycling exercise efficiency. Trained participants with cycling experience will be recruited. Participants will perform three trials in a randomized order. Each trial will involve a 3-minute warm-up followed by an incremental ramp test. The ramp will initially consist of three, 5-minute stages performed at relative workloads corresponding to 75%, 100%, and 125% of individual ventilatory threshold intensity. This will be followed by a further incremental ramp test 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 using a randomized, double-blind crossover design. Diet prior to exercise will be standardized between trials for a given participant. 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.