Socio-ecological predictors of non-organized physical activity participation and decline between childhood and adolescence.

Physical activity (PA) tends to decline during late childhood and adolescence. In Australia, this decline has been shown to particularly occur non-organized PA (e.g., active play, informal sport). This study aimed to explore predictors of non-organized PA at 13y; and decline between 11y and 13y. Data were sourced from the Longitudinal Study of Australian Children. Non-organized PA was measured using time-use diaries. Analyses included Cragg hurdle and binary logistic regressions. The likelihood of non-organized PA at 13y was predicted by PA enjoyment (OR = 1.36, p = 0.007), number of siblings (OR = 1.11, p < 0.001), sex (females) (OR = 0.66, p < 0.001) and home computer use at 11y (OR = 0.98, p = 0.002) (n = 3,193). Females also engaged in less non-organized PA at 13y (β = -77.77, p = 0.048) (n = 3,193). Significant predictors of decline in non-organized PA were socioeconomic position (OR = 0.92, p = 0.047) and sugary drink consumption at 11y (OR = 1.06, p = 0.033) (n = 3,222). Strategies to promote non-organized PA may include targeting females and those of lower socioeconomic position, and focusing on types of PA that may replace the perceived benefits of computer use.