The purpose of this study is to examine the effect of exogenous ketone body supplementation on carbohydrate metabolism during exercise. In a randomized, crossover, and double-blind study, 20 endurance trained adult males and females aged 18-50 years, will ingest carbohydrates with either a ketone monoester supplement before and throughout a 3-hour exercise session or carbohydrates with a flavour-matched ketone-free placebo. The main aim of this study is to compare the exogenous carbohydrate oxidation rates during exercise between the ketone monoester and placebo conditions.
18-50 years of age
Trained cyclist/triathlete (VO2peak > 55 ml/kg/min for males and >48 ml/mg/min for females)
Healthy as per medical history and investigator's/physician's judgement
Having given written informed consent
Use of medication that could impact study outcomes and/or interfere with the expected mechanism of action of ketone supplements (e.g. Chronic use of gastric acid suppressing medication, statins, corticosteroids)
Smoking
Diagnosed acute or chronic medical conditions that, in the opinion of the investigator, could impact study outcomes (e.g. Diabetes mellitus)
Diagnosed musculoskeletal disorders
Crossover
CHO+KETONE
Dietary supplementSports drink containing glucose and ketone mono-esters
CHO+PLACEBO
Dietary supplementSports drink containing glucose and placebo
Exogenous carbohydrate oxidation rate
Exogenous carbohydrate oxidation rate during exercise measured by 13C enrichment in breath. CHO+KETONE vs CHO+PLACEBO condition
Endogenous carbohydrate disappearance rate
Endogenous carbohydrate disappearance rate during exercise measured by stable isotope tracer methodology. CHO+KETONE vs CHO+PLACEBO condition
Exogenous carbohydrate disappearance rate
Exogenous carbohydrate disappearance rate during exercise measured by stable isotope tracer methodology. CHO+KETONE vs CHO+PLACEBO condition
Total carbohydrate disappearance rate
Total carbohydrate disappearance rate during exercise measured by stable isotope tracer methodology. CHO+KETONE vs CHO+PLACEBO condition
Exogenous carbohydrate appearance rate
Exogenous carbohydrate appearance rate during exercise measured by stable isotope tracer methodology. CHO+KETONE vs CHO+PLACEBO condition
Total carbohydrate oxidation
Total carbohydrate oxidation during exercise, measured indirectly by using traditional stoichiometric calculations of carbohydrate oxidation. CHO+KETONE vs CHO+PLACEBO condition
Blood parameters
Plasma glucose, insulin, glycerol, free fatty acids, and ketone body concentrations (including area under the curve) following drink ingestion. CHO+KETONE vs CHO+PLACEBO condition
Exercise economy during cycling
Exercise economy during the exercise trial. CHO+KETONE vs CHO+PLACEBO condition, will be determined based on the amount of work performed during cycling (workload), and the amount of energy expenditure as measured by indirect calorimetry.
Exercise heart rate
Heart rate during exercise. CHO+KETONE vs CHO+PLACEBO condition
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