Reducing sedentary behaviour in older adults with mobility limitations.

Sedentary behaviour — time spent sitting or lying while awake — is strongly associated with poor cardiometabolic health, frailty, and early mortality. These risks are especially pronounced for older adults with limited mobility, who may have few opportunities to be physically active and face structural barriers to reducing sitting time. Yet at the time this PhD began, almost no behaviour change trials had specifically targeted sedentary time in this population — research had focused on physical activity in healthier older adults, leaving people with mobility limitations underserved by the evidence base.

The PhD proceeded in three phases: a systematic review of existing interventions; development and measurement work to design a targeted behaviour change programme; and a randomised controlled trial — the INTEREST (INTErvention to REduce Sitting Time) study — which recruited older adults with osteoarthritis from NHS orthopaedic surgery services. I was Chief Investigator of the trial, which ran in complex real-world NHS conditions. The findings are reported in my 2020 thesis and a series of peer-reviewed papers.

The systematic review found no published trials that had specifically targeted sedentary behaviour in older adults with mobility limitations — a gap this PhD was designed to fill.