Physiological response to a short period of exercise training in patients with chronic heart failure

BACKGROUND AND PURPOSE: Whilst cardiac rehabilitation is regularly offered to patients recovering from a myocardial infarction, people with chronic heart failure are often excluded from exercise training programmes. This study was designed to investigate the effects of eight weeks' exercise training in patients with moderate chronic heart failure. METHOD: Eight male patients entered a 16-week randomized, controlled, crossover study of two months' exercise training versus a control period. They performed supervised training three times a week and measures of indices of aerobic function and exercise tolerance were performed monthly throughout the study period. RESULTS: After training, the time walked on a treadmill during an exercise tolerance test increased from 14.8 min (95% CI; range 10.4-18.1 min) to 15.9 min (range 12.1-15.9 min). Significant changes at peak exercise levels (p < 0.05) were seen in oxygen uptake increasing from 3.4 metabolic equivalents (METs) (95% CI; range 2.6-4.2 METs) to 4.0 METs (range 3.2-4.9 METs), and in cardiac index, improving from 5.0 l/min-1/m-2 (95% CI; range 2.9-8.1 l/min-1/m-2) to 5.5 l/min-1/m-2 (range 3.0-9.4 l/min-1/m-2). Resting heart rate decreased significantly (p < 0.05), from 84 beats/min-1 (95% CI; range 73-105 beats/min-1) to 76 beats/min-1 (range 64-90 beats/min-1). Blood flow measurements by venous occlusion plethysmography showed a 21.5% decrease (range 58.5-238.9%) in resting blood flow to the lower leg and a 31.6% increase (range -7.2% to 52.5%) after submaximal exercise, but these changes were not significant (p > 0.05). All benefits were lost within two months of ceasing regular exercise. CONCLUSION: This study demonstrated that patients with moderate chronic heart failure derived beneficial physiological responses from eight weeks' exercise training, but these were soon lost after cessation of regular exercise.