Content of the intervention
FMS
FMS
The aim of the intervention was to improve father-child co-PA, and consequently the objectively measured PA levels of both. Secondary aims of the intervention were to target (co-) sedentary behaviour (SB), body mass index (BMI), family health climate regarding PA and the quality of father-child relationship. The Behaviour Change Wheel (BCW) was used as a theoretical framework to systematically develop the intervention [In brief, the intervention was implemented over 14 weeks, including two components: (1) a practical component in which six (inter)active sessions were given face-to-face to the fathers and children, of 120 min each, and (2) an eHealth component which was implemented throughout the entire 14-week intervention period (for a timeline, see Fig. For the intervention, participants were randomly assigned to a group, each containing about 12 father-child days. These groups received the same sessions, on a different evening in the same week. The main facilitator was always the same for the three groups, the supporting 2 facilitators were different for the three different groups, minimizing the change of a clustering effect due to participating in the same groups for the entire study duration. The face-to-face sessions took place at the same elementary school in Ghent, East-Flanders (Belgium). Each face-to-face session consisted of a 40-minutes education component and a 60-minute practical component part (see Fig. 
Overview of the Run Daddy Run themes across the six sessionsAfter the education component, goals were set by the fathers and children on co-PA. In the subsequent practical component, several exercises were performed with each session focusing on specific fundamental movement skills (FMS) (see Table Second, the eHealth component consisted of a website (
Timeline of the Run Daddy Run intervention under normal circumstances
Timeline of one practical father-child session