Background As we get older, our risk of disability increases. Disability affects quality of life and increases health and social care costs. Preventing disability is therefore important, and identifying an effective intervention should improve the lives of many older people. Evidence suggests physical activity may reduce the risk of age-related disability, however it is unclear what approach is most cost-effective in changing long-term physical activity behaviour in older adults. A new theory-driven behavioural intervention has been developed, with the aim of increasing physical activity in the lives of older adults at risk of disability. This study tests the feasibility and acceptability of delivering the intervention to older adults.

Methods Using postal invitations and opportunistic waiting room recruitment, participants were recruited from primary care practices around Bristol during 2014–15. Patients were eligible to participate if they were aged over 65, inactive, not disabled, and were at risk of developing disability in the future (Short Physical Performance Battery score <10/12).

Enrolled participants were randomised to intervention or control arms. Those randomised to the intervention arm received face-to-face and telephone support sessions with a trained Physical Activity Facilitator (PAF), delivering an intervention based on self-determination theory over six months. Control participants receive a booklet on healthy ageing.

Following completion of the PAF intervention, or six months after enrolment, all participants were asked to attend a follow-up clinic where outcome measures were taken. The main outcomes of interest in the pilot study are recruitment, adherence, retention and acceptability. Data were also collected on: self-report and accelerometer-recorded physical activity; physical performance; depression; wellbeing; cognitive function; social support; quality of life, healthcare use, and adverse events.

A mixed-methods process evaluation was run alongside the RCT, including qualitative interviews with participants and PAFs, and questionnaires measuring the theoretical components of the intervention.

Results Out of 1875 postal invitations sent out by practices 1317 (70%) of patients responded with 349 (26%) expressing an interest in the study. 192 (55%) fitted the initial eligibility criteria and were invited to a clinical screening appointment.

51 patients (26%) fitted the full eligibility criteria and were enrolled. All participants were randomised (2:1 ratio) to either intervention (n = 34) or control (n = 17). Data on key outcome measures and qualitative findings will be presented.

Discussion If cost-effective, this intervention could improve quality of life for older adults. Before proceeding to a full-scale trial this study is necessary to ensure intervention feasibility and acceptability, and to explore whether the intervention shows evidence of promise.