Liiiisa Dear Liiiisa, You're on the right track, but athletes' protein, carbohydrate, fat, and calorie requirements can vary, depending on many factors. Let's talk about endurance athletes first. They train aerobically for an hour or more at a time, which requires a lot of energy. Since muscles prefer to burn carbohydrates for fuel, serious aerobic exercisers need plenty of these.
Muscles utilize glycogen for fuel during exercise.
When glycogen runs low, the body may resort to burning protein for energy. When this happens, endurance athletes' protein needs increase. These levels can remain low if people exercise day after day without eating enough carbs to replenish their supply. In either case, their bodies resort to utilizing protein for energy during workouts. Adding carbohydrates to your overall eating plan prevents this from happening.