Composition of objectively measured physical activity and sedentary behaviour participation across the school-day, influence of gender and weight status: cross-sectional analyses among disadvantaged Victorian school children.
The after-school period has been described as the 'critical window' for physical activity (PA) participation. However, little is known about the importance of this window compared with the before and during-school period among socioeconomically disadvantaged children, and influence of gender and weight status.



39 out of 156 (RR=25%) invited primary schools across 26 local government areas in Victoria, Australia, consented to participate with 856 children (RR=36%) participating in the wider study. The analysis sample included 298 Grade 4 and Grade 6 children (mean age: 11.2±1.1; 44% male) whom met minimum accelerometry wear-time criteria and had complete height, weight and health-behaviours questionnaire data. Accelerometry measured duration in daily light-intensity PA (LPA), moderate-to-vigorous PA (MVPA) and sedentary time (ST) was calculated for before-school=8-8:59, during-school=9:00-15:29 and after-school=15:30-18:00. Bivariate and multivariable linear regression analyses were conducted.



During-school represented the greatest accumulation of LPA and MVPA compared with the before and after-school periods. Boys engaged in 102 min/day of LPA (95% CI 98.5 to 104.9) and 62 min/day of MVPA (95% CI 58.9 to 64.7) during-school; girls engaged in 103 min/day of LPA (95% CI 99.7 to 106.5) and 45 min/day of MVPA (95% CI 42.9 to 47.4). Linear regression models indicated that girls with overweight or obesity engaged in significantly less LPA, MVPA and more time in ST during-school.



This study highlights the importance of in-school PA compared with after-school PA among socioeconomically disadvantage children whom may have fewer resources to participate in after-school PA.
World Health Organization's Collaborating Centre for Obesity Prevention, Deakin Population Health, Deakin University, Geelong, Victoria, Australia.
Claudia
C
Strugnell
Nuffield Department of Population Health, British Heart Foundation Centre on Population Approaches for Non-Communicable Disease Prevention, University of Oxford, Oxford, Oxfordshire, UK.
Kyle
K
Turner
World Health Organization's Collaborating Centre for Obesity Prevention, Deakin Population Health, Deakin University, Geelong, Victoria, Australia.
Mary
M
Malakellis
World Health Organization's Collaborating Centre for Obesity Prevention, Deakin Population Health, Deakin University, Geelong, Victoria, Australia.
Josh
J
Hayward
Nuffield Department of Population Health, British Heart Foundation Centre on Population Approaches for Non-Communicable Disease Prevention, University of Oxford, Oxford, Oxfordshire, UK.
Charlie
C
Foster
World Health Organization's Collaborating Centre for Obesity Prevention, Deakin Population Health, Deakin University, Geelong, Victoria, Australia School of Health and Social Development, Deakin University, Geelong, Victoria, Australia.
Lynne
L
Millar
World Health Organization's Collaborating Centre for Obesity Prevention, Deakin Population Health, Deakin University, Geelong, Victoria, Australia School of Health and Social Development, Deakin University, Geelong, Victoria, Australia.
Steve
S
Allender
D061725:Accelerometry; D001835:Body Weight; D002648:Child; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D016014:Linear Models; D008297:Male; D050177:Overweight / Q000453:epidemiology; D063766:Pediatric Obesity / Q000453:epidemiology; D012574:Schools; D057185:Sedentary Behavior; D057566:Self Report; D012737:Sex Factors; D013997:Time Factors; D014739:Victoria / Q000453:epidemiology; D035862:Vulnerable Populations / Q000706:statistics & numerical data*
disadvantaged; obesity; physical activity