Table 2.

Example of experimental intervention for one week in phase I

Weekday	Intervention at the health promotion centre	Independent training in own environment	Notes to health professionals
Monday	Duration: 90 min Warm-up: short walk in a group to the walking point (either a park or an area near the health promotion centre). Interval Walking Training: every patient does Interval Walking Training with the InterWalk app for a minimum of 30 min. Every patient does the Interval Walking Training by themselves so that the app instructions during the session can be followed. The health professionals guide and facilitate the individual patient if necessary. After the Interval Walking Training everyone goes back to the health promotion centre. Group conversation at the health promotion centre after doing interval walking with all participating patients. Different focus areas are discussed in the group. Everyone sits on a chair and the health professional participates as a facilitators in the group conversation (examples of focus areas: weather conditions, motivation for exercise, social needs when waking, motivation for a physically active everyday life).		Remember to encourage and guide every patient to do Interval Walking Training three times a week either by themselves or together with other patients. Make sure that everyone is active during the walking sessions. If a patient needs to do a new walking test then it is the health professional who should help during the intervention period. Every patient needs a new test every fourth week.
Tuesday	Rest day
Wednesday	Duration: 90 min Warm-up: short walk in a group to the walking point (either a park or an area near the health promotion centre). Interval Walking Training: every patient does Interval Walking Training with the InterWalk app for a minimum of 30 min. Every patient does the Interval Walking Training by themselves so that the app instructions during the session can be followed. The health professionals guide and facilitate individual patient if necessary. After the Interval Walking Training everyone goes back to the health promotion centre. Group conversation at the health promotion centre after doing interval walking with all participating patients. Different focus areas are discussed in the group. Everyone sits on a chair and the health professional participates as a facilitators in the group conversation (examples of focus areas: weather conditions, motivation for exercise, social needs when waking, motivation for a physically active everyday life).
Thursday	Rest day
Friday	Rest day
Saturday		Interval walking using the InterWalk application for 30–60 min. Can be carried out alone or together with other patients.
Sunday	Rest day

Patients allocated to the experimental intervention do interval walking twice a week, 30–60 min per session during phase I at the health promotion centre in small groups of 3–12 patients. A third session is conducted in the patient's everyday life environment.