Carbohydrates become the predominant fuel source during high-intensity exercise. This is because carbohydrate oxidation can produce ATP more rapidly than fat oxidation, supporting the quick energy demands of intense efforts. Key points:
- At rest and during low to moderate intensities, fat is a major energy contributor, but as intensity increases, the demand for ATP rises and carbohydrate becomes increasingly important. During high-intensity exercise, carbohydrate oxidation supplies the majority of ATP needed, often approaching or exceeding two-thirds of total energy, with glycolysis providing rapid ATP both aerobically and anaerobically. This shift reflects the faster rate of ATP production from carbohydrate metabolism compared to fat metabolism.
- The dependence on carbohydrate is evident across common sources: muscle glycogen and blood glucose are the primary carbohydrate substrates fueling high-intensity activity. Fat oxidation rates are insufficient alone to meet the energy demands at high intensity, leading to a predominant CHO role.
- Practical takeaway: for athletes or activities requiring sustained high-intensity output, ensuring adequate carbohydrate availability through diet or fueling strategies is crucial to maintain performance, delay fatigue, and support repeated high-intensity efforts.
If you’d like, I can tailor this to a particular sport or provide an ultra- brief summary for a slide or handout.
