Slow-SPEED UK: A Double-Blind Randomised Feasibility Trial

Slow-SPEED UK is an 18-month randomised, double-blind feasibility trial evaluating the delivery, adherence, and acceptability of a digitally supported physical activity programme in community-dwelling adults aged 40 and over with objectively confirmed hyposmia (reduced sense of smell) and low baseline physical activity. Participants are randomly assigned 1:1 to either a full-dose activity-support programme (targeting a 100% increase in daily step count) or a very low-dose active control (targeting a 10% increase). Both arms are delivered via a smartphone application linked to a wearable activity monitor (Fitbit Charge 6), with personalised weekly goals expressed as relative percentages to maintain blinding. The study is not designed to test clinical efficacy.