Correlates of intensity-specific physical activity in children aged 9-11 years: a multilevel analysis of UK data from the International Study of Childhood Obesity, Lifestyle and the Environment.

OBJECTIVES: Physical activity (PA) can provide numerous physical and psychological health gains, yet a low proportion of children in England are sufficiently active to accrue benefit. Analysing the correlates of PA from a socioecological perspective may help to identify factors that promote versus discourage PA. The purpose of the present study was to: (1) assess the relationships between a wide range of potential correlates and intensity-specific PA and (2) explore which correlates are associated with meeting government PA guidelines. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional study on children aged 9-11 years from the South West of England (n=425; 183 males). OUTCOME MEASURES: A mixture of self-reported and objective measures (eg, body mass index (BMI), accelerometer-derived PA, self-reported sport participation, etc) were collected from child participants, parents and school teachers. After adjusting for covariates (ie, age, sex and accelerometer wear time), multilevel modelling techniques were employed to examine the relationships between potential correlates and light-intensity, moderate-intensity and vigorous-intensity PA, as measured with an ActiGraph GT3X+ accelerometer. Generalised linear mixed modelling was used to analyse the correlates associated with government-recommended levels of PA. RESULTS: Computer use shared a negative association whereas parent support for PA showed a positive relationship with light-intensity PA. In terms of moderate-intensity PA, computer use and BMI z-score shared a negative association whereas positive relationships were found for sport participation, active transport and for outdoor time after school. Children at schools with 25%-49% of pupils attending school sport/PA clubs did more moderate-intensity PA than those attending schools with lower participation rates. For vigorous-intensity PA, a negative relationship was observed for BMI z-score, and positive associations for self-efficacy, active transport, parent support and the presence of crossing guards on routes to school. Correlates associated with meeting the PA guidelines were BMI z-score (negative), sport participation, active transport and outdoor time after school (all positive). CONCLUSION: Results demonstrate that factors pertaining to the individual, home and school environment may play an important role in understanding the correlates of differing PA intensities in children. TRIAL REGISTRATION NUMBER: NCT01722500.