Inclusion Criteria:  in World Health Organisation (WHO) Functional Class II or III have a diagnosis of PH have started on PH drug therapy in the preceding 18 months showing no signs of worsening breathlessness or heart failure on an unchanged PH therapeutic regime for at least 6 months prior to inclusion.  Exclusion Criteria:  have an active infection or acute exacerbation of lung disease have participated in a clinical study involving another investigation of drug, device or exercise within the previous 6 months are on a surgical or other pathway of care that has pre-determined physiotherapy or activity regimes or restrictions have any additional medical conditions that may adversely affect the safety of the subject or severely limit the lifespan of the subject have participated in rehabilitation in the last 12 months.