Exercise intensity and duration are the main factors that influence the contribution of carbohydrates vs. fats as fuel to make ATP. Exercise intensity increase cells use a higher ratio of carbohydrate to make ATP.
ATP obtained from lipid oxidation is over twice the amount obtained from carbohydrate and amino acid. During the high intensity exercise , carbohydrate are the major fuel source. During low intensity exercise fat is the primary source of fuel your body uses.
Oxidation reactions in the cytoplasm and mitochondria of cell produced ATP and carbohydrate , proteins and fats undergo a series of metabolic reactions collectively called cellular respiration.
