Brooks & Mercier 1994, Balance of carbohydrate and lipid utilization during exercise: the “crossover” concept

Journal of Applied Physiology 76(6):2253-2261. Theoretical framework for how exercise intensity and prior endurance training set the balance of carbohydrate and fat oxidation. The “crossover point” is the power output at which carbohydrate-derived energy comes to predominate over lipid; raising intensity beyond it shifts the mix further towards carbohydrate, while endurance training moves the crossover to a higher power output (more fat used at a given absolute intensity). Foundational and widely cited; moderate.