A randomized, non-blinded prospective intervention trial. Patients randomized to exercise intervention will undergo supervised aerobic training on ergometer cycle for 12 weeks whilst control group receives standard care. Before and after the intervention, all participants will undergo cardiac magnetic resonance imaging (cardiac MR) examinations, Ventilation/Perfusion Single Photon Emission Computed Tomography (V/P SPECT), Cardiopulmonary exercise tests, muscle biopsies and blood sampling.
The objective of this study is to assess by what physiological mechanisms patients with heart failure benefit from exercise. Effects of an exercise intervention will be assessed for both central (heart and lungs) and peripheral (muscle fiber and mitochondria) factors.