Introduction The effects of carbohydrate supplementation on endurance performance and the associated changes in substrate oxidation during normoxia are well researched (Coyle et al., 1986; Hargreaves et al., 1984; Jeukendrup et al., 1999; King et al., 2018; Smith et al., 2013; Tsintzas et al., 1996). Current guidelines promote the ingestion of ‘multiple transportable carbohydrate’ during prolonged exercise to maximize substrate oxidation (Baur & Saunders, 2021).