The ketone body beta-hydroxybutyrate is produced during prolonged fasting or exercise and can be used as an alternative fuel source. Exogenous beta-hydroxybutyrate, in the form of a ketone salt, is proposed to have ergogenic potential for high-intensity exercise performance but this has not been adequately studied. The purpose of this study is to determine whether supplementing with an acute dose of ketone salts can alter fuel use during exercise and improve exercise performance.