Intervention delivery
In the verbal advice group, the GP verbally advised patients to increase their daily physical activity using the following standardised wording: “Try to do at least 15 min of brisk walking or another activity that makes you breathe faster than normal every day of the week”. The GP repeated this advice every three months during scheduled follow-up consultations if the patient was still judged as being insufficiently active.In the PPIL group, the GP wrote a personalised physical activity prescription stating the number of daily steps to be taken and provided a pedometer (Omron HJ-321-E, a compact tri-axial pedometer to be carried in a pocket or a bag), information about the benefits of physical activity, and a logbook to keep daily physical activity records. The GP and participant agreed on an achievable target number of steps to be taken each day above the participant’s baseline activity level. This was then indicated on the written prescription. For example, “4000 steps above your usual number of steps”. The GP encouraged the participant to try reaching the prescribed target over a three-month period by setting intermediate weekly goals.The first week, participants continued their normal daily routine and recorded their average daily step count. The second week, the intermediate weekly goal was set by adding a mutually agreed number of steps to their normal average step count. This continued until the target was reached. Activities not logged by the pedometer such as swimming, cycling, and gardening, could be recorded in the logbook using the included conversion table. Participants were asked to bring their logbook to each follow-up consultation at study month 3, 6, and 9 during which the participant and GP reassessed the target step number together.At study month 3 and 12, participants received the self-assessment kit containing the accelerometer to wear for seven consecutive days and the self-administered questionnaires (IPAQ, SF-36, and Determinants of Physical Activity Questionnaire (DPAQ)). After seven days, they returned the kits for centralised treatment.