ABSTRACT
AIMS: No consensus exists regarding the most appropriate exercise testing protocol for patients with congestive heart failure. This study describes the effect of exercise training on performance using three different protocols (maximal, submaximal and endurance testing) in patients with heart failure. METHODS AND RESULTS: Thirty men (mean age 67+/-8 years) with congestive heart failure in NYHA class III (mean ejection fraction 32+/-5%) were evaluated prior to and following exercise training. A maximal exercise cycle test with gas exchange measurements, a submaximal 6 min walk test and an endurance treadmill test with blood lactate sampling were used to evaluate exercise capacity after 12 weeks of exercise training. There was a 44.6% (P<0.001) increase in work performed during the maximal cycle test, with no significant increase in peak VO(2). The distance covered by the submaximal 6 min walk test increased by 8.1% (P<0.001). Lactate measured as area under the curve during the matched work intensity treadmill endurance test was reduced by 19.5% (P<0.005). CONCLUSION: We demonstrated a significant improvement in maximal, submaximal and endurance exercise capacity following 12 weeks of exercise training in patients with congestive heart failure. Endurance tests may be more sensitive and appropriate when assessing the efficacy of intervention in this population. Specifically, demonstration of reduced lactate production at matched work intensities suggests more efficient work and decreased dependence on anaerobic metabolism following training. Although maximal cycle tests are commonly used in clinical work, submaximal and endurance testing might be preferable for evaluating new treatment regimens in this population as they are easy to perform, are reproducible, and reflect daily tasks better than the maximal cycle test in this population.
