Income-based inequalities in self-reported moderate-to-vigorous physical activity among adolescents in England and the United States: a cross-sectional study
Objective: Quantify inequalities in self-reported moderate-to-vigorous physical activity (MVPA) in England and the United States (US). Design: Population-based cross-sectional study. Participants: 4019 adolescents aged 11-15 years in England (Health Survey for England 2008, 2012, 2015) and 4312 aged 12-17 years in the US (National Health and Nutrition Examination Survey 2007-16). Main outcome measures: Three aspects of MVPA: (1) doing any, (2) average min/day (MVPA: including those who did none), and (3) average min/day conditional on participation (MVPA-active). Using hurdle models, we quantified inequalities (average marginal effects: AMEs) using the absolute difference in marginal means. Results: In England, adolescents in high-income households were more likely than those in low-income households to have done any formal sports/exercise in the last seven days (boys: 11%; 95% CI: 4% to 17%; girls: 13%; 95% CI: 6% to 20%); girls in high-income households did more than their low-income counterparts (MVPA: 6 min/day, 95% CI: 2 to 9). Girls in low-income households spent more time in informal activities than girls in high-income households (MVPA: 21 min/day; 95% CI: 10 to 33), whilst boys in low-income versus high-income households spent longer in active travel (MVPA: 21 min/week; 95% CI: 8 to 34). In the US, in a typical week, recreational activity was greater among high-income versus low-income households (boys: 15 min/day; 95% CI: 6 to 24 min/day; girls: 19 min/day; 95% CI: 12 to 27). In contrast, adolescents in low-income versus high-income households were more likely to travel actively (boys: 11%; 95% CI: 3% to 19%; girls: 10%; 95% CI: 3% to 17%) and do more. Conclusions: Policy actions and interventions are required to increase MVPA across all income groups in England and the US. Differences in formal sports/exercise (England) and recreational (US) activities suggest that additional efforts are required to reduce inequalities.