Metabolism of Exercise States 100 meter sprint energy source used pre-synthesized ATP creatine phosphate anaerobic glycolysis 100 meters to 1 kilometer energy source used oxidative phosphorylation 1 kilometer to a marathon energy source used glycogen β-oxidation of fatty acids Metabolism of Exercise States Absorptive state immediately after eating insulin in control insulin-sensitive tissues login to view 3 more bullets pathways favored by insulin login to view 4 more bullets insulin-resistant tissues login to view 2 more bullets Post-absorptive state between meals epinephrine/glucagon in control glucagon-sensitive tissues login to view 2 more bullets pathways favored by glucagon login to view 4 more bullets glucagon-resistant tissues login to view 2 more bullets Starvation days 1-3 main source of energy for body login to view 1 more bullet main source of energy for brain login to view 1 more bullet > 3 days main source of energy for body login to view 1 more bullet main source of energy for brain login to view 1 more bullet > several weeks main source of energy login to view 2 more bullets main source of energy for brain login to view 2 more bullets note: RBCs are always dependent on glucose