Cycle exercise causes a lower ventilatory response to exercise in chronic heart failure.

P atients with chronic heart failure (CHF) complain of breathlessness and fatigue. Their exercise limitation can be assessed by incremental exercise testing with metabolic gas exchange to derive peak oxygen consumption (pV̇O2). The slope of the relation between ventilation (V̇E) and carbon dioxide production (V̇CO2), V̇E/V̇CO2 can characterise the ventilatory response to exercise. CHF patients have a reduced pV̇O2 and an increased V̇E/V̇CO2 slope. 1 Thus, for a given V̇CO2, the ventilatory response is greater. These two measures are inversely related in patients, but not controls, and both are related to prognosis. The form of exercise undertaken, stationary cycle or treadmill, varies between exercise laboratories. Treadmill based protocols achieve higher values of pV̇O2 and anaerobic threshold than those using a cycle. The effects of the different exercise modes on the V̇E/V̇CO2 slope and the symptoms of breathlessness are unknown. The aim of the present study was to explore the effect of cycle and treadmill exercise on ventilation and symptoms.