Table 2.

Domain concepts and descriptions developed from expert, child and parent input integrated with systematic literature review.

Domain	Description
Physical Activity	Physical Activity refers to one's level of bodily movement and performance of activities that require physical actions, ranging from simple static behaviors with minimal muscle activity to more complex activities that require dynamic or sustained muscle activity and greater movement of the body. The Physical Activity item pool should consist of a range of items that estimate the amount of complex physical movements and behaviors and the contexts in which they occur. The underlying hierarchical factor is relative energy expenditure. Thenon-hierarchical context characteristics reflect the purpose of the activity (e.g. self-care, sports, school, and recreation), physical environment (e.g. school home, community) and social situations (e.g. alone, family, peers).
Sedentary Behaviors	Sedentary Behaviors are behaviors that require minimal effort and reflect a high level of inactivity that can be characterized by duration, temporal (time of day) and contextual coverage of purpose (screen time, transportation, socializing, work/school (non-discretionary), environment and social situations.
Strength Behaviors	Strength Behaviorsreflect the capacity of individuals to perform functional activities of daily living that require significant amount of muscle force generation. Items may includea phrase (e.g. “were you strong enough to…”) providing attribution of the functional capacity to one’s strength.