Influence of School Beverage Environment on the Association of Beverage Consumption With Physical Education Participation Among US Adolescents

摘要

Objectives. We examined the association of adolescents’ beverage consumption with physical activity and studied how their school beverage environment influences the association. Methods. We used nationally representative data from the 2007 Early Childhood Longitudinal Study—Kindergarten Cohort (n?=?8850). We examined nonlinear associations of eighth graders’ self-report of beverage consumption (milk, 100% juices, soft drinks) with moderate to vigorous physical activity and physical education (PE) participation using piecewise linear regression models. Results. We found a nonlinear association of participation in PE class with beverage consumption, especially in schools with vending machines and those selling soft drinks. For students participating in PE less than 3 days per week, beverage consumption was not significantly associated with participation in PE class frequency. For students participating in PE 3 to 5 days per week, 1 more day of participation in PE class was associated with 0.43 (SE?=?0.14; P =?.002) more times per week of soft drink consumption and 0.41 (SE?=?0.17; P =?.021) fewer glasses per week of milk consumption. Conclusions. The more soft drink and less milk consumption related to high participation in PE class might be prevented by improving the beverage environment in schools. Systematic environmental interventions are needed to prevent such potential unintended consequences of promoting physical activity. More than 30% of US children are overweight or obese. 1,2 Because most children spend more than half their waking time in school, there are 2 widely espoused strategies to fight the obesity epidemic: to eliminate competitive foods and to promote physical activity in school. 3,4 An increasing number of states and school districts has established policies requiring students’ regular physical education (PE) participation 5,6 to promote physical activity, although observational studies have not found the school physical activity–related environment to influence schoolchildren’s body weight status. 7–10 In the meantime, US parents are aware of the availability of unhealthy foods and beverages in children’s sports settings. 11 It is unknown whether sports and physical activity prevent childhood obesity, especially in an obesogenic food environment. Youths’ sports participation has been associated with more consumption of both healthier (e.g., milk and 100% fruit juice) and less healthy (e.g., sugar-sweetened) beverages. 12 A 2004–2005 survey in Texas of 11th graders showed that boys who are more active consume sugar-sweetened flavored and sports drinks more frequently than do less active boys. Their physical activity decreased with more frequent soda consumption, but physical activity increased among boys having the highest soda consumption. 13 This is likely attributable to the fact that children who are more physically active have greater fluid intake 14 because of their increased need to rehydrate. However, to our knowledge, this nonlinear relationship between physical activity and beverage consumption has not been examined in previous research. Furthermore, availability of beverages in the environment may affect the association of physical activity with beverage consumption, resulting in the nonlinear finding in the Texas survey. More than 50% of US middle school students can buy soft drinks at their schools, regardless of the state-level policies restricting soft drinks on campus. 15–17 As US adolescents’ weekly frequency of participation in PE class has been increasing in the past decade, 18 how promoting physical activity in schools with available soft drinks influences children’s beverage consumption needs closer examination. We hypothesized that US adolescents’ physical activity and participation in PE class would be associated with milk and soft drink consumption in a nonlinear fashion. Furthermore, we hypothesized that the associations may be modified by the school food environment (i.e., availability of soft drinks and vending machines). We examined these hypotheses using nationally representative survey data of US eighth-grade adolescents from the Early Childhood Longitudinal Study—Kindergarten (ECLS-K) cohort.