Chronic heart failure (CHF) is a clinical syndrome presented with central, cardiac deterioration as well as peripheral vascular and muscular abnormalities, resulting finally to reduced exercise tolerance, quality of life and mortality rates. Exercise training is a major component of rehabilitation / secondary prevention interventions, inducing significant beneficial changes in mechanisms of pathophysiology, exercise tolerance, functional capacity and quality of life, while a positive impact on hospitalization and mortality reduction should not be also excluded. There has been growing interest in the characteristics and modalities of exercise training able to induce optimal benefits. High intensity and interval mode have been shown to induce greater benefits than moderate intensity and continuous mode regimes. Additionally, there has been sound rationale for the inclusion of strength training, which has been also shown able to yield benefits in terms of exercise capacity and quality of life. However, there haven't been much data on the so called combined regimes, which include both aerobic exercise and strength training. This study aims at investigating the effects of combined high-intensity interval and strength training compared to high-intensity interval exercise alone in CHF.

Inclusion Criteria:

• stable heart failure
• ejection fraction <=45%
• optimal medical treatment
• NYHA class <=III

Exclusion Criteria:

• contraindications for maximal cardiopulmonary exercise testing (CPET)
• moderate to severe COPD
• inability to follow exercise programs due to orthopaedic problems