In recent years, evidence has emerged that exercise, carefully prescribed, can be safely used in PH patients and can significantly improve symptoms and enhance quality of life. To date, PH exercise programmes have involved a preparatory 3-week induction period to educate and empower the patients in exercise and lifestyle, familiarize them with the exercises and personalize the programme. This phase is followed by a 12-week home-based exercise programme. In Germany, patients attend the induction period as inpatients, whereas in Scotland they make daily outpatient visits, availing of hotel accommodation. This study aims to assess the feasibility, acceptability and safety of a 12-week home-based exercise programme, preceded by a new 3-week induction process with 2-day meetings each week. Participants will complete tests and questionnaires to measure physical, clinical and psychological outcomes at the beginning of the study, 13 weeks later (control phase) prior to induction, and following the completion of the 12-week programme (week 27). The 12-week control phase will allow participants with PH to act as their own controls and ensure that they are stable prior to exercise training commencement. My research project will only evaluate the baseline aerobic fitness, physical activity levels, muscle strength, pulmonary function and QOL of the participants. The research study is a collaboration between the School of Health and Human Performance at DCU and consultant physicians in the Pulmonary Hypertension Unit at the Mater Misericordiae University Hospital, Dublin.