This study aimed to evaluate the impact of combined carbohydrate and 1,3-butanediol (CHO-BD) supplementation on endurance performance, blood beta-hydroxybutyrate (βHB) concentration, and glycolytic activity, compared to carbohydrate supplementation alone (CHO). Ingested ketogenic agents, such as ketone bodies, have the potential to enhance endurance performance by providing an alternative exogenous and glycogen-sparing fuel source.