Exercise Snacks Enabled by an mHealth Intervention Delivered in General Practice to Promote a Sustainable Active Lifestyle in Adults With Obesity

Adults with obesity gain as much from regular physical activity as anyone else, but structured exercise programmes are hard to sustain once the programme ends. This trial tests a different approach, built around exercise snacks, that is short bouts of activity of a few minutes at a time, spread through an ordinary day. Physically inactive adults aged 18 to 65 with obesity are invited by their own general practitioner. Everyone who takes part receives a wrist-worn activity tracker and keeps it at the end of the study. Participants are allocated at random in two steps. At the start, two out of every three take part in a six-month programme of supervised group exercise sessions and individual counselling based on motivational interviewing. The remaining third receives the tracker together with brief standardised advice on physical activity. After six months, everyone who took part in the programme is allocated at random a second time, half and half: one half receives an automated conversational agent that supports them by message for the following twelve months, and the other half receives no further support. The trial asks two questions. First, whether the six-month programme increases physical activity compared with the tracker and brief advice alone. Second, whether the automated conversational agent helps participants sustain their activity over the following year. Physical activity is measured with a research-grade accelerometer worn on the wrist for one week at the start, at six months and at eighteen months. Aerobic fitness, cardiometabolic blood markers, physical function and wellbeing are measured at the same three visits.