From my own reading, there are three ways used by the body to produce energy:
Alactic anaerobic (direct degradation of ATP and creatine phosphate for regeneration of ATP)
Lactic anaerobic (breakdown of muscle glycogen with lactic acid production)
Aerobic (breakdown of carbohydrates and fats primarily and secondarily of proteins)
My questions are:
1) Knowing that the anaerobic mechanisms (alactic and lactic) are triggered when the effort is intense and / or greater than body oxygenation capacity, it seems logical, at rest, the body uses mainly aerobic way for producing energy. Am I right?
2) If 1) is true, what are the conditions (trigger elements, trigger events) which lead to muscle catabolism (so protein degradation) in order to produce energy? ? Is it well the last resort used by the body to produce energy that is to say after degradation of total carbohydrates and lipids?