Socioecological and biological associations of lower levels of physical activity in 8-year-old children: a 2-year prospective study

OBJECTIVES: Evaluate if socioecological and biological factors, at the age of 8 years, are associated with lower level of physical activity (PA) 2 years later. METHOD: In a study cohort of 199 children aged 7.8±0.6 years, we used questionnaires and physical measurements to evaluate biological (eg, sex), social (eg, parental PA) and environmental (eg, school settings) factors. Objective PA was measured 2 years later with accelerometers. General PA (GPA) was defined as mean counts per minute (cpm) and moderate to vigorous PA (MVPA) as min/day >3500 cpm. We used analysis of covariance to evaluate if socioecological factors at age 8 are associated with level of PA 2 years later. RESULTS: Daily GPA was 690.5±216.6 cpm and the children spent 40.9±18.3 min on MVPA. Female sex is associated with −131.1 (−183.4, –78.7) cpm GPA, each 10 cm shorter body height with −48.7 (−94.8, –26.5), each unit higher body mass index (BMI) with −26.0 (−37.5, –14.5) and allocation to 60 min school PA/week with −73.8 (−131.5, –16.2) compared with allocation to 200 min school PA/week. Female sex is associated with −10.3 (−14.8, –5.7) min of MVPA and each unit higher BMI with −1.9 (−2.9, –0.9) min. CONCLUSION: Female sex, shorter body height and higher BMI are at age 8 years associated with lower level of PA 2 years later. It appears possible to increase PA by daily school PA. TRIAL REGISTRATION NUMBER: NCT00633828.