The integrative cardiorespiratory exercise test

The cardiorespiratory incremental maximal exercise test is being used increasingly for clinical evaluation. It is based on the fact that during physical effort the output of the cardiovascular and respiratory systems increase to maintain a higher metabolic rate and stroke volume. Cardiac output increases by increase in both heart rate and stroke volume. Ventilation increases by increase in respiratory rate and tidal volume. All changes are synchronous, so that blood composition and gas partial pressures are constant over a wide range of work intensities. The response of a normal sedentary subject to incremental exercise is presented, as well as the improvement in an athlete's physical performance as a result of training. An obese subject, despite normal maximal oxygen uptake, felt compromised due to the high energy cost of moving his heavy torso. The large normal breathing reserve during exercise was demonstrated in 2 subjects who, despite lung disease, responded normally to the test. It is likely that this test will be widely used for evaluation of patients with heart and lung disease.