THE CORRELATION OF YOUTH PHYSICAL ACTIVITY WITH STATE POLICIES

Childhood overweight has risen dramatically in the United States during the past three decades. The search for policy solutions is limited by a lack of evidence regarding the effectiveness of state policies for increasing physical activity among youths. This paper estimates the correlation of student physical activity with a variety of state policies. We study nationwide data on high school students from the Youth Risk Behavior Surveillance System for 1999, 2001, and 2003 merged with data on state policies from several sources. We control for a variety of characteristics of states and students to mitigate bias due to the endogenous selection of policies, but we conservatively interpret our results as correlations, not causal impacts. Two policies are positively correlated with participation in physical education (PE) class for both boys and girls: a binding PE unit requirement and a state PE curriculum. We also find that state spending on parks and recreation is positively correlated with two measures of girls' overall physical activity. (JEL 118, 128) 1. INTRODUCTION Over the past three decades, the prevalence of overweight among American youth has risen dramatically. The Centers for Disease Control and Prevention (CDC) defines childhood overweight (1) as a body mass index (2) (BMI) above the 95th percentile for children of the same age and gender (benchmarked against the historic BMI distribution).(3) Since 1970, the fraction overweight has almost quadrupled among adolescents aged 12-19 yr (Ogden et al.. 2002). As of 1999-2002, 16% of children aged 6-19 yr are clinically overweight, a figure three times greater than the Healthy People 2010 (4) goal System of 5% (Hedley et al., 2004; IOM, 2005; U.S. Department of Health and Human Services, 2000). The increasing prevalence of overweight children is a major public health concern because of its implications for physical health (Ebbeling, Pawlak, and Ludwig, 2002; Kimm and Obarzanek, 2002), mental health (Puhl and Obarzanek, 2002; Strauss, 2000), and medical care costs (Johnson, Mclnnes, and Shinogle, 2006; Wang and Dietz, 2002). The amount of physical activity that youths engage in is important for several reasons. First, overweight is the result of energy imbalance--more calories consumed than expended--so increasing physical activity while keeping caloric intake constant decreases the risk of overweight (Institute of Medicine, 2005). Second, even controlling for body weight, those who engage in more physical activity tend to be in better health; in particular, they have improved cardiovascular functioning, stronger musculoskeletal systems, improved mental health and emotional well-being, and decreased risk of developing chronic disease such as type 2 diabetes and hypertension (Institute of Medicine, 2005; U.S. Department of Health and Human Services, 1996). As a result, current recommendations are for youths to engage in a minimum of 60 min of moderate to vigorous physical activity daily (Institute of Medicine, 2005; National Association for Sport & Physical Education, 2004). There is little convincing evidence regarding the cost effectiveness of programs to increase physical activity or otherwise reduce or prevent childhood overweight (Cawley, 2007). The Institute of Medicine's (2005) report Preventing Childhood Obesity: Health in the Balance concludes: The research literature is at a much earlier stage of determining which programs work at all (Cawley, 2007). Two years after the Institute of Medicine (IOM) report on preventing childhood obesity, a follow-up IOM report concluded that an essential priority action for the near future remains "learning what works and what does not work and broadly sharing that information" (Institute of Medicine, 2007, p. 410). Most of the studies that have been conducted are based on randomized experiments of particular school-based interventions to modify physical education (PE) curriculum or improve school meals (Doak et al. …