The aim of this study was to evaluate the effectiveness of a novel group-based aerobic interval training of high intensity on functional capacity and quality of life in patients with chronic heart failure (CHF) and examine the relation between changes in functional capacity and quality of life. Eighty patients with stable CHF (63 men, 17 women; mean age 70.1 +/- 7.9 [SD] years; left ventricular ejection fraction 30 +/- 8.5%) on optimal medical treatment were randomly assigned to either a 16-week group-based aerobic high-intensity interval training model twice weekly for 65 to 80 minutes/day (n = 40) or a control group (n = 40) that received standard care. Functional capacity was measured using the 6-minute walk test and cycle ergometer test. Quality of life was measured using the Minnesota Living with Heart Failure Questionnaire. After 16 weeks, functional capacity improved significantly in the exercise group compared with the control group measured using the 6-minute walk test (+58 vs -15 meters; p <0.001) and for both workload and time measured using the bicycle ergometer test (+10 vs -1 W; p < 0.001; + 57 vs -8 seconds; p <0.001). Quality of life improved significantly in the exercise group compared with the control group (p = 0.03), and a significant inverse correlation was found between quality of life and functional capacity (r = -0.49, p <0.05). In conclusion, our exercise model significantly improved functional capacity and quality of life compared with the control group in patients with CHF. Improvements in quality of life were significantly related to functional capacity.