Exercise training by interval versus steady-state modus in chronic heart failure: improvement of functional capacity, hemodynamics and quality of life - a controlled study

We conducted a three-week randomized trial comparing the improvement of functional capacity by exercise training in chronic heart failure by the steady-state (EF 27.3%, n=20) and the interval modus (EF 29.3%, n=20) with a control group (EF=26.6%, n=10). Minimal EF was 10%, the lowest maximal oxygen consumption was 9.3 ml/kg/min and the lowest cardiac output was 1.9 l/min; 9 patients had been evaluated for HTX. VO2 at the anaerobic threshold and at maximal exercise increased in the continuous exercise group by 1.4 or 1.6 ml/kg/min, respectively, corresponding to an increase of 13.7% (p<0.05) and 9.3% (p<0.05). In the interval training group the increase was 1.3 and 1.5 ml/kg/min corresponding to 14% (p<0.05) and 8.1% (p<0.05). Continous short-term exercise had no impact to central hemodynamics as pulmonary artery pressure (PA), capillary wedge pressure (pc), cardiac index (CI) or stroke volume index (SVI), whereas after interval training a significant increase at maximal exercise could be seen in CI (p<0.05) and SVI (p<0.01) with a concomitant drop in systemic peripheral resistance (P<0.05) compared to the steady-state modus. Interval training was further characterized by a higher short-term but lower mean work load with a significantly smaller increase in lactate. Quality of life was improved according to the SF-36 questionnaire in both training groups but the psychologic sum factor was three times as high, increasing to 24.2% in the steady-state exercise group. It can be concluded that clinically stable patients with heart failure and even those already having been evaluated for cardiac transplantation profit from short-term physical training. Both training modalities seem equally suited to improve functional capacity. However interval training leads to more pronounced improvement in hemodynamics compared to the steady-state exercise, whereas the later had a greater impact on psychological well-being and quality of life. Patients with heart failure and severe peripheral deconditioning tolerate higher workloads with more peripheral stress by an interval training modus. Long-term training modalities need to be established to further improve and stabilize functional status.