Many youth today are physically inactive. Considerable evidence documents that nearly 35% of youth in the US fail to meet the minimum physical activity guidelines, and another 14% are completely inactive [1
]. Low levels of physical activity and the failure to meet physical activity recommendations have notable health consequences among children including increased risk of obesity [3
], low bone density [4
], and low physical fitness [5
]. Furthermore, children who are not physically active are denied the positive social and emotional benefits of physical activity including higher self esteem, lower anxiety, and lower stress [6
]. A comprehensive understanding of the determinants of physical activity among youth is essential for the identification of appropriate points of intervention to promote active lifestyles and their associated health benefits. In this paper, we examine environmental influences on children's physical activity. Specifically, we review research assessing the association between attributes of the physical environment and children and adolescents' physical activity.
The physical or built environment has come to the forefront of public health research in the past 5 years, leading to a surge of research on environmental attributes and their associations with physical activity behaviors. A number of reviews have examined links between the physical environment and adults' physical activity [7
]. Much less emphasis has been placed on research specific to children. One cannot assume that associations between the physical environment and physical activity among adults are applicable to children. As highlighted by Krizek, Birnbaum & Levinson [13
], children in contrast to adults, spend large parts of their day at school, have considerable time for recreation, are more likely to accumulate physical activity through play, are not able to drive, and are subject to restrictions placed on them by adults.
Two reviews to date are specific to children. In 2000, Sallis et al. [14
] published a comprehensive review of predictors of physical activity among youth. Studies published between 1970 and 1998 were included in the review. While this review does not focus on the physical environment, a small proportion of the 108 studies reviewed are specific to the physical environment. More recently, in 2005, McMillan [15
] reviewed studies in both planning and public health literatures on urban form and children's trip to school. McMillan outlines policies and programs that may promote walking and cycling to school (e.g., Safe Routes to School) and highlights the lack of focus on children in the transportation literature. In the absence of research on environmental factors that affect children's trips to school, most of the studies reviewed by McMillan focus on adult populations.
In this descriptive review, we build on the work of Sallis et al. and McMillan by reviewing recent studies (published between 1990 and 2006) that examine the association between children's physical activity and environmental attributes (perceived and objectively measured). In particular, we provide specific information on the sample characteristics and design of each study, evaluate consistencies and inconsistencies in the literature, and identify gaps in the current research and possible avenues for future research. In addition, we broaden the set of children's behaviors from their trip to school as outlined by McMillan to physical activity in general. In order to serve both the need for understanding the link the physical environment and physical activity among youth and the implementation of next steps based on these findings, we use an organizing schema that identifies the parties responsible for specific elements in the built environment.