• Difference in change over time between the rehabilitation and the control group in SF-36 [ Time Frame: Baseline, 4 weeks, 15 weeks ]
  Health related quality of life (HRQoL) will be measured by the extensively validated generic HRQoL questionnaire, the 36-Item Short Form Survey Instrument (SF-36). This questionnaire includes two main scores with a physical component and an emotional component scale and eight subscales. The score ranges between 0 and 100, higher scores indicate a better quality of life. The questionnaire is self-administered and will be completed on paper
• Difference in change over time between the rehabilitation and the control group in EmPHasis-10. [ Time Frame: Baseline, 4 weeks, 15 weeks ]
  Health related quality of life (HRQoL) will be measured the EmPHasis-10 questionnaire, measuring the impact of PH on health related quality of life. The score ranges between 0 and 50, higher scores indicate worse quality of life.
• Change from baseline to 15 weeks between the rehabilitation and the control group in WHO functional class [ Time Frame: Baseline, 15 weeks ]
  The WHO functional classification ranges from class I (patients with PH but without resting limitation of physical activity) to class IV (patients with PH with inability to carry out any physical activity without symptoms). The WHO functional class is a powerful predictor of survival in patients with PH.
• Difference in change over time between the rehabilitation and the control group in Borgscale at the end of the 6MWD test [ Time Frame: Baseline, 4 weeks, 15 weeks ]
  Borg (0-10) scale reporting on dyspnea and fatigue will be administered at the end of the six-minutes walk test. The score ranges between 0 and 10, a higher score means more symptoms of dyspnea / fatigue.
• Change from baseline to 15 weeks between the rehabilitation and the control group in maximal exercise capacity [ Time Frame: Baseline, 15 weeks ]
  Maximal exercise capacity will be assessed by a maximal incremental cycling test. After a 2-min resting period and 3 minutes of unloaded cycling, the patients will start at 20 W and cycle until symptom limitation at an incremental workload of 10 W/min. Oxygen consumption, carbon dioxide output and ventilation will be measured breath by breath (Vmax series, SensorMedics, Anaheim, CA). Heart rate and oxygen saturation will be registered continuously. Peak workload, oxygen consumption (VO2 max), heart rate, blood pressure, oxygen saturation, ventilation and VE/VCO2 slope will be retrieved.
• Difference in change over time between the rehabilitation and the control group in Objectively measured physical activity [ Time Frame: Baseline, 4 weeks, 15 weeks ]
  At every time point, physical activity will be measured for 1 week, using a physical activity monitor validated to be used in patients with respiratory disease. Patients will be asked to wear the monitor during waking hours. The mean number of steps per day and time spent in activities of at least moderate intensity will be retrieved as outcomes.
• Difference in change over time between the rehabilitation and the control group in symptoms of anxiety and depression (HADs questionnaire) [ Time Frame: Baseline, 4 weeks, 15 weeks ]
  Symptoms of anxiety and depression will be assessed by the Depression, Anxiety, and Stress Scale. This questionnaires is self-administered and will be completed on paper. Higher scores indicate more symptoms of anxiety / depression.
• Difference in change over time between the rehabilitation and the control group in Isometric quadriceps force [ Time Frame: Baseline, 4 wekes, 15 weeks ]
  An isometric maximal volitional contraction of the right quadriceps muscle be performed using the Biodex dynamometer with the patient seated with a 90° hip and 60° knee flexion. The best of 3 reproducible measurements will be retrieved as a measure of quadriceps force.
• Change from baseline to 15 weeks between the rehabilitation and the control group in hemodynamics measured by echocardiography [ Time Frame: Baseline, 15 weeks ]
  Hemodynamics measured by echocardiography at rest and during a symptom limiting exercise test. The following outcomes will be investigated: Change in tricuspid annular plane systolic excursion, Change in tissue Doppler imaging, Change in left ventricular pump function, Change in right ventricular pump function , Change in thickness of interventricular septum, Change insize of inferior vena cava, Change in systolic pulmonary arterial pressure, Change in left ventricular eccentricity index, Change in Tei index , Change in right ventricular area, Change in right atrial area
• Change from baseline to 15 weeks between the rehabilitation and the control group in proportion of patients who exceeded the MID in 6MWD [ Time Frame: Baseline, 15 weeks ]
  MID will be defined as an increase of at least 30m
• Change from baseline to 15 weeks between the rehabilitation and the control group in heart function as measured by MRI (optional) [ Time Frame: Baseline, 15 weeks ]
  MRI scan at rest and during exercise combined with right heart catherization and blood sampling before and after the exercise protocol.
• adverse events [ Time Frame: 15 weeks ]
  Patients will be asked about visits to general practitioner and hospitalizations due to any medical reasons in order to control the occurrence of adverse events. In a semi-structured way,, occurrence of exercise related and non-exercise related adverse events will be collected.

• Experimental: Rehabilitation group
  15 weeks pulmonary rehabilitation program consisting of 2 weeks inpatient, 2 weeks outpatient and 11 weeks home-based rehabilitation.
  Intervention: Other: Pulmonary rehabilitation
• No Intervention: Control group
  Usual care

Inclusion Criteria:

• Female and male patients ≥ 18 years
• Pulmonary arterial hypertension (PAH, Group 1 of Nice classification) and chronic thromboembolic pulmonary hypertension (CTEPH, group 4)
• WHO functional class II-III

• PH diagnosed by right heart catheter showing:

  1. Baseline mean pulmonary arterial pressure (mPAP) ≥ 25 mmHg
  2. Baseline pulmonary vascular resistance (PVR) ≥ 240dyn x s x cm-5
  3. Baseline pulmonary capillary wedge pressure (PCWP) ≤ 15 mmHgg
• Patients receiving optimized conventional PH therapy including intensified treatment with diuretics and who have been stable for 2 months before entering the study.
• Except for diuretics, medical treatment should not be expected to change during the entire 15-week study period.
• Negative pregnancy test (β-HCG) at the start of the trial and appropriate contraception throughout the study for women with child- bearing potential
• Able to understand and willing to sign the Informed Consent Form

Exclusion Criteria:

• PH of any cause other than permitted in the entry criteria, e.g. concomitantly to portal hypertension, complex congenital heart disease, reversed shunt, HIV infection, suspected pulmonary veno-occlusive disease based on pulmonary edema during a previous vasoreactivity test or on abnormal findings compatible with this diagnosis (septal lines or pulmonary edema at high resolution computer tomography), congenital or acquired valvular defects with clinically relevant myocardial function disorders not related to pulmonary hypertension or unclear diagnosis
• Patients with signs of right heart decompensation
• Walking disability
• Acute infection, pyrexia
• Any change in disease-targeted therapy within the last 2 months
• Any subject who is scheduled to receive an investigational drug during the course of this study
• Severe lung disease: FEV1/FVC <0.5 and total lung capacity <70% of the normal value
• Active myocarditis, instable angina pectoris, exercise induced ventricular arrhythmias, decompensated heart failure, active liver disease, porphyria or elevations of serum transaminases >3 x ULN (upper limit of normal) or bilirubin >1.5 x ULN
• Hemoglobin concentration of less than 75% of the lower limit of normal
• Systolic blood pressure <85 mmHg
• History or suspicion of inability to cooperate adequately