Introduction: Moderate-intensity endurance-training is known to reduce symptoms, increase exercise tolerance, and improve quality of life in patients with chronic heart failure. The training benefits have mainly been attributed to adaptations in the peripheral circulation and skeletal muscle rather than to adaptations in cardiac performance. However attenuation of left ventricular (LV) remodelling has been documented in some studies. The effects of high- vs. moderate exercise-intensity on LV-remodelling and endothelial function in patients with post-infarction heart failure are not definitively established and were studied in the present study.

Methods: Patients with post-infarction heart failure (45-87 yrs, 22-males, 5-females, all received b-blockers and ACE-inhibitors, EF 29%, peak oxygen uptake 13 ml/kg/min) were randomized to 12-weeks, 2-3 times per week, of either moderate exercise-intensity (70% of peak heart rate), high-intensity interval-training (95% of peak heart rate) or to a control group that received advise from their regular doctors. Patients in the two exercise-groups covered similar distance on the treadmill at each exercise-session so that only exercise-intensity differed; i.e. the duration of exercise was longer in the moderate-intensity group. Ultrasound was used to assess LV-dimension and function (including Tissue Doppler Imaging, TDI) and endothelial function in the brachial-artery.

Inclusion Criteria:

Post-infarction heart failure and optimal treatment (ACE-inhibitors, Beta-blockade)

Exclusion Criteria:

Not able to walk on a treadmill, unstable angina, participating in another experiment, serious arrhythmia