Teun Remmers

4 | Chapter 1 Determinants of Physical Activity in Youth Development of effective PA interventions requires knowledge about determinants of PA. Several conceptual frameworks propose that PA is surrounded by individual-level factors and various layers of environmental factors (20). Some frameworks even provide insight into possible pathways by which environmental factors, individual factors or socio- demographical factors might influence PA (21, 22). For example, the Environmental Research framework for weight Gain prevention (EnRG framework) postulates that environmental factors (i.e. in the physical, sociocultural, political or economic domain) are directly related to PA, but also via cognitive mediators such as perceived behavioral control or attitude. In addition, this framework also identifies individual-level cognitive factors (e.g. habit strength, gender, personality traits) that moderate both the direct and indirect pathways between environmental factors and PA (21, 23). Determinants at the Individual Level One of the most consistent factors associated with children's PA is gender. In almost all observational and experimental studies, boys are more active than girls (24-26). Also, there is solid evidence that PA declines with age in the transition from childhood to adolescence (10-15-year-olds) (6, 27, 28). Only a few studies have suggested that lower social-economic status or ethnic background may also be related to PA, potentially via less PA-supportive lower social-economic status neighborhoods (29). Inspired by for example the Theory of Planned Behavior (30) and the Social Cognitive Theory (31), there has been considerable interest in socio-cognitive factors that might explain children's PA intention and self-reported PA behavior (32, 33). Social-cognitive theories describe a merely conscious pathway of reasoned action and planning towards behavior, whereas children's PA is considered spontaneous and intermittent (34, 35). Therefore, these social-cognitive theories explain bigger proportions of variance for intention compared to self-reported behavior (32). Alternatively, the Self Determination Theory describes a spectrum of types regarding quality of motivation. This spectrum describes a continuum of four externally fostered motivational types (i.e. external, introjected, identified and integrated regulation) where the source of motivation can be for example a reward of avoidance of negative affect. At the other end of the spectrum, motivation can be intrinsic when it is fostered from the enjoyment of the activity itself, without discernible reinforcement of reward (36). Generally, results from previous studies showed that more autonomous forms of motivation were related to more PA in physical education and leisure time, but strength of these associations were weak (37). Also, children who are intrinsically motivated experience higher levels of PA enjoyment, and may thus be more likely to be active compared to other children (38). However, based on the idea of Physical Literacy (39), motivation, attitude and self-concept may only be part of a larger multidimensional construct that determines a child's capacity to interact with its environment through physical movement (40). A physical literate child has the physical capacities (e.g. fundamental movement skills), the psychological capacities (e.g. perceived competence and enjoyment) and behavioral capacities (e.g. self-regulatory skills) to interact in various PA-contexts (40).