Data collection
Participants were given the option of face-to-face, telephone or video conference calls at a mutually convenient time, but all opted for telephone interviews. All interviews were audio-recorded and participants provided recorded verbal consent after being read a consent form. Participants were sent a £20 gift voucher to thank them for their time.All interviews were conducted by MB, a male consultant physiotherapist who has qualitative research training. The interviewer was not known to the participants but they were aware that he was the chief investigator for the OPTimisE pilot and feasibility trial. Participants were encouraged to speak freely about their opinions, whether positive or negative.Interviews were semi-structured, using a topic guide developed by MB and BS (see 
