Teun Remmers

Investigating moderation between determinants of children's outside play | 69 Background Physical activity (PA) is key to prevent and reverse childhood overweight and obesity, resulting in the incorporation of PA in international guidelines of the World Health Organization (i.e. 60 minutes of daily moderate to vigorously intense PA) (1). Despite the well-known benefits, about half of the children in the U.S. and the Netherlands do not meet this guideline (2-3). Established correlates of children’s PA behavior are male gender, PA enjoyment/preferences, and peer support (4-9). In addition, increasing evidence suggests that attributes of the perceived physical environment such as functionality, traffic safety, attractiveness, and accessibility are also associated with PA (10-13). Evidence for this relationship in children is however mixed (11, 13). This mixed evidence is greatly influenced by differences in the measurement of attributes of the physical environment and PA (objective versus subjective) and a lack of systematic investigation of moderators of environmental influences (14). In addition, several PA domains (e.g. outside play, organized sports, active transport) may have different environmental correlates (e.g. outside play is conceptually matched to playgrounds rather than active transport). Conceptual mismatching of attributes of the physical environment to specific PA domains may be another reason for the mixed evidence in children (15, 16). Outside play (i.e. PA without any given tasks or goals; unstructured free play) is such a PA domain, that has been recommended as most appropriate to increase PA in young children (17). Outside play has been shown to contribute substantially to children’s total PA levels (12, 18-23) also in different specific contexts such as school grounds, sports facilities, urban green space and active transport (24). In addition, outside play is positively associated with children’s social skills as they learn to account for each other (25-27) and provides challenges that foster the development of new motor skills in a self- regulatory way (28). In order to promote outside play effectively, the determinants of this behavior should be examined. Three studies have examined correlates of outside play duration related to the physical and social environment, and have reported that the family environment (e.g. parental rules, parental attitudes regarding outside play) was the strongest construct of variables related to outside play, and that the perceived physical environment was considered promising in fostering PA, but they appear to explain a small proportion of outside play (29-31). Based on several conceptual ecological frameworks and an umbrella review of Ding and colleagues (12-15), it is recommended to include potential moderators in the investigation of the relationship between physical environment and PA behavior (14). The perceived physical environment can directly influence children’s outside play behavior, but the strength of this relationship may depend on activators / inhibitors of the social environment. More specifically, parents may play a crucial role in a child’s relative exposure to the perceived physical environment, and thus also on outside play. Investigating the moderating influence of the social environment on the relationship between the perceived physical environment and outside play is thus a crucial next step in