Quick fact. Ready?
When one becomes more aerobically fit, such as with prolonged endurance activities, one’s body becomes more efficient at burning fat, as supposed to carbs, over a wider range of intensity outputs. This helps to preserve muscle glycogen, and thus helps to combat fatigue.
I see you've been getting a lot of vet asks an questions. So here's a non-vet ask: herbivorous dragons, around what is the maximum size do you think they could attain? I'm thinking something along the lines of an enormous iguana or beardie. Also, could they muster up enough metabolic energy to fuel flight? Assuming in this instance that dragons are cold-blooded, but may have some specialized adaptations for circulating body heat to where it's most needed, like white sharks do.