Pulmonary hypertension (PH) refers to a heterogeneous group of diseases characterized by vasoconstriction and structural remodelling of the pulmonary arteries. Increased vascular resistance and elevated pulmonary arterial pressures contribute to right ventricular hypertrophy and eventually lead to heart failure and premature death (Hoeper et al., 2013;Simonneau et al., 2019). Symptoms of PH are progressive and include serious exercise intolerance, reducing the quality of life of patients. Important pathophysiological mechanisms contributing to exercise intolerance and fatigue in PH include right ventricular dysfunction and inflammation, which among other things result in skeletal muscle alterations and dysfunctional energy metabolism (Tran et al., 2018;. Currently, PH is divided into 5 subgroups according to the classification of the World Health Organisation (WHO), European Respiratory Society (ERS) and European Society of Cardiology (ESC). The first subgroup is pulmonary arterial hypertension (PAH), WHO type 2 PH is related to left heart disease, type 3 PH is due to lung disease and hypoxia, type 4 is due to chronic thrombo-embolic pulmonary hypertension (CTEPH) or other pulmonary artery obstructions, while type 5 PH is due to multifactorial mechanisms (Galiè, Humbert, et al., 2015). PAH consists of different subgroups based upon different underlying disorders, such as PAH due to genetic mutations, congenital heart disease, connective tissue disease, liver disease, HIV, and, when the etiology is unknown: idiopathic PAH. In both PAH and CTEPH the disease originates in the pulmonary arteries. Those patients are typically treated with PH-specific therapies in expert centers, whereas other PH patients receive different treatment.