Exercise training in patients with chronic heart failure delays ventilatory anaerobic threshold and improves submaximal exercise performance. Circulation

We have recently demonstrated that exercise training can induce important hemodynamic and metabolic adaptations in patients with chronic heart failure due to severe left ventricular dysfunction. This study examines the accompanying changes in submaximal exercise perfor-mance and the ventilatory response to exercise in these patients. Before and after 16-24 weeks of exercise training, subjects underwent two symptom-limited bicycle exercise tests, one with an incremental graded workload, and one vwith a constant workload that represented 79±11 % of the pretraining peak oxygen consumption. Breath-by-breath expired gas analysis was per-formed continuously during each test, and central hemodynamic, leg blood flow, and blood lactate measurements were obtained during the incremental protocol. The ventilatory anaerobic threshold was determined during the incremental exercise study from coplotted breath-by-breath ventilatory data with standard criteria by observers who were unaware of patient identity or training status. As previously reported, exercise training increased peak oxygen consumption by 23 % from 16.8±3.8 to 20.6±4.7 ml/kg/min and reduced blood lactate levels during submaximal exercise. The training-induced decrease in lactate accumulation was accompanied by a decrease in carbon dioxide production, respiratory exchange ratio, an