Background & Significance: The role of a healthy diet and physical activity in obesity prevention is well-established, but the importance of different constructs of sedentary behaviours is uncertain. This study sought to investigate relationships between volume, patterns and types of sedentary behaviour and adiposity in children.
Methods: An observational case-control study of obese and healthy-weight 10-13 year olds (130 male, 104 female) recruited via media advertisements was conducted. Adiposity was quantified using percent body fat measured using dual-energy X-ray absorptiometry and waist-to-height ratio (WHtR). Use-of-time was assessed using accelerometry and the Multimedia Activity Recall for Children and Adolescents (MARCA). Time (volume), type (television, videogame, computer, eating, passive transport) and bout length (patterns) of sedentary behaviours were measured. Moderate-to-vigorous physical activity, total daily energy expenditure, sleep, age, average annual household income and Tanner stage were included as covariates in partial least squares analyses, stratified by gender.
Major Findings: Television time ranked as the most important type of sedentary behaviour, demonstrating positive associations with adiposity in both genders. Prolonged bouts of sedentary behavior and time playing computer/video games were positively correlated with adiposity, but only in boys. In girls, non-screen sedentary behaviour was inversely associated with adiposity. Total sedentary time was only inconsistently linked with fatness after appropriate adjustments.
Concluding statement: These data confirm that limiting television time is an important target for childhood obesity interventions. Furthermore, other characteristics of sedentary behaviour beyond total volume also show sex-specific associations with adiposity. Therefore, further research is needed to inform current volume-based sedentary behaviour guidelines.
Funding: Grant from the Physiotherapy Research Foundation. Dr Tsiros also received an Australian Post Graduate Award.