Assessing the effect of exercise training in men with heart failure - Comparison of maximal, submaximal and endurance exercise protocols

Aims No consensus exists regarding the most appropriate exercise testing pr otocol 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 he art failure in NYHA class III (mean ejection fraction 32 +/- 5%) were evalu ated prior to and following exercise training. A maximal exercise cycle tes t with gas exchange measurements, a submaximal 6 min walk test and an endur ance treadmill test with blood lactate sampling were used to evaluate exerc ise capacity after 12 weeks of exercise training. There was a 44.6% (P<0.00 1) increase in work performed during the maximal cycle test, with no signif icant increase in peak VO2. The distance covered by the submaximal 6 min wa lk test increased by 8.1% (P<0.001). Lactate measured as area under the cur ve during the matched work intensity treadmill endurance test was reduced b y 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 sensit ive and appropriate when assessing the efficacy of intervention in this pop ulation. Specifically, demonstration of reduced lactate production at match ed work intensities suggests more efficient work and decreased dependence o n 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.