MUSCLE PHYSIOLOGY

Detailed explanation-1: -In some situations, however, such as when we eat too few calories daily or not enough carbohydrate, as well as during latter stages of endurance exercise, when glycogen reserves are depleted, skeletal muscle is broken down and used as fuel.

Detailed explanation-2: -In a high-intensity workout, although your body uses your glycogen stores first for ‘fast energy’, it depletes the glycogen stores rapidly enough to force your body to tap on the fat storage. This means that high-intensity workouts are more efficient in burning way more total calories – both glycogen and fat calories.