Role of ATP supply in limiting reserve cardiac power output

Reserve cardiac power output (CPO) is the additional rate of mechanical work done by the heart in maximal exercise compared to the work rate at resting conditions. Recruitment of cardiac work and cardiac output during exercise requires matching mitochondrial ATP synthesis to increases in ATP consumption. We hypothesize that the physiological maximal capacity of the myocardium to do mechanical work is limited by the maximal capacity of myocardial mitochondria to synthesize ATP at free energy levels necessary to drive cardiac contraction.