Pulmonary hypertension (PH) is defined as a mean pulmonary arterial pressure ≥25 mmHg. PH is often diagnosed at an advanced stage (WHO functional class III-IV) with a massive increase of the mean pulmonary arterial pressure. A crucial parameter determining the symptoms and prognosis of the patients is the cardiac reserve. This parameter is defined by the pulmonary vascular resistance and the right ventricular adaptation. Severe PH is characterized by a decreased cardiac output at rest, an increased afterload and consecutive cor pulmonale.

Within the last years there has been a huge progress in the scientific fields of genetics, pathogenesis, pathophysiology and therapy of PH. This has also been documented in the PH world conferences. New disease-targeted medication has been developed such as endothelin receptor antagonists (bosentan, ambrisentan, sitaxentan, macitentan), prostacyclin derivates (inhaled and intravenous iloprost, epoprostenol, treprostinil), phosphodiesterase-5-inhibitors (sildenafil, tadalafil) and the soluble guanylate cyclase inhibitor riociguat. Despite these advances in treatment, the disease may not be treated causally or even be cured. In most cases however, disease progression may be slowed down. The use of PH-targeted treatment and supporting therapies such as anticoagulation and diuretics improve the symptoms and impede the progression of the disease. Nevertheless, the prognosis of the patients remains impaired. The first randomized controlled study investigating the effect of exercise training in PH showed a significant improvement of exercise capacity and quality of life. Further uncontrolled trials using a low-dose exercise and respiratory therapy in different etiologies of PH showed an improvement in exercise capacity, quality of life, muscle function and further prognostic parameters. A recent randomized controlled study could support these findings. Studies also showed an improvement in muscle capillarization of the quadriceps muscle.

The training program consists of interval ergometer training, respiratory therapy, muscle training and mental gait training. The interval ergometer training allows performing aerobic exercise training with a low cardio-circulatory stress. In patients with left heart insufficiency, this training has been successfully implemented. Respiratory therapy has been established in the rehabilitation of patients with lung disease within the last years. The different techniques aim to improve ventilation, strengthen the respiratory muscles, mobilize the thorax and enhance secretolysis. The training program also contains mental (gait) training. This training was adapted from mental imagery techniques used by sport psychologists in professional athletes. Mental imagery techniques have shown to improve physical and cognitive functions.

Due to the beneficial results, exercise training and rehabilitation has received a 1A recommendation at the PH world symposium in Nice in 2013. This decision was mainly based on three randomized controlled trials that investigated a limited number of patients. To unequivocally demonstrate safety and positive effects of exercise training in different settings large multicenter RCTs are essential. An exercise program has not yet been implemented in most European countries, partly due to limited access to rehabilitation programs and institutions.

The aim of this large, multicenter, prospective, randomized controlled trial is to investigate the effect of exercise training and rehabilitation on physical exercise capacity across different European countries. Physical exercise capacity will be measured by exercise induced change of 6-minute walking distance (6-MWD) compared to baseline and the control group without training. As inpatient settings are not available in all healthcare systems the training program will be adapted from the specific training program for PH patients developed in Heidelberg in a system, which is feasible for the local participating centres. Another objective of this study is to assess if the adopted training program specified for each participating centre and country is still safe and effective.