Increasing inequality in physical activity among Minnesota secondary schools, 2001-2010

Two Healthy People goals are to increase physical activity (PA) and to reduce disparities in physical activity among adolescents.  PA promotion in secondary schools has been a focus of national efforts.  We examine self-reported PA among 540,709 students attending 1,365 regular secondary schools in Minnesota for the period 2001-2010 from the Minnesota Student Survey (MSS).  Student responses were linked to school demographic data from the National Center for Educational Statistics, and at a subset of schools in each year school policies and practices from the Minnesota School Health Profiles study. We estimated random-effects regression models to account for the same schools over time.  Overall, students who met PA standards increased from 63.2% in 2001 to 66.8% in 2010 (p<0.001).  However, the gains in PA occurred at lower FRPL schools (<20% - 62.9% in 2001 to 70.0% in 2010, p<0.001; 20-50% - 64.1% in 2001 to 67.4% in 2010, p<0.001) while high FRPL schools remained the same (< 50% - 61.6% in 2001 and 61.7% in 2010).  High FRPL schools were primarily located in urban areas and enrolled racial/ethnic minority students. A large increase in school-level FRPL occurred over time (30.3% in 2001 to 39.8% in 2010, p<0.001).  Changes associated with FRPL were independent of individual characteristics and school policy and practice.  Strengths of this study include the large number of schools and consistency in data collection methodology.  Limitations include measurement imprecision and lack of fit with current activity recommendations.