If muscle work is anaerobic what cannot serve as fuel?

If muscle work is anaerobic, oxygen cannot serve as fuel. During anaerobic exercise, the body relies on energy sources that do not require oxygen, such as stored ATP and creatine phosphate, as well as anaerobic glycolysis that breaks down glucose into lactic acid. Consequently, fats and carbohydrates that require oxygen for efficient metabolism cannot be utilized effectively in this energy system.