Physical Activity Awareness of British Adolescents.

OBJECTIVE To assess adolescent PA awareness and investigate associations with biological and psychosocial factors. DESIGN Cross-sectional from November 2005 to July 2007 (ROOTS study). SETTING Population-based sample recruited via Cambridgeshire and Suffolk schools (UK). PARTICIPANTS N=799 (44% male, 14.5±0.5 years). MAIN EXPOSURES Self-rated PA perception, self-reported psychosocial factors, measured anthropometry. OUTCOME MEASURE PA measured using accelerometry over five days. 'Inactive' defined as accelerometry-measured <60 min/day of at least moderate PA (MVPA). Associations between awareness (agreement between self-rated and accelerometry-measured active/inactive) and potential correlates investigated using multinomial logistic regression. RESULTS 70% of adolescents were inactive (81% of girls, 56% of boys, OR(95% CI) 3.41(2.41, 4.82)). 53% of all girls (63% of inactive girls) and 34% of all boys (60% of inactive boys) inaccurately rated themselves as active (over-estimators). Compared to girls accurately describing themselves as inactive (29%), girl over-estimators had lower fat mass (OR(95% CI) 0.84(0.70, 0.99)), higher SES (high vs. low 2.4(1.07, 5.32)), reported more parent-support (1.57(1.12, 2.22)) and better family relationships (0.25(0.09, 0.67)). Amongst boys accurately describing themselves as inactive (22%), over-estimators had lower fat mass (0.86(0.77, 0.96)) reported more peer-support (1.75(1.32, 2.30)) and less teasing (0.75(0.61, 0.92)). CONCLUSIONS A substantial number of adolescents believe themselves to be more physically active than they really are. They maybe unaware of potential health risks, and may be unlikely to participate in PA promotion programs. Increasing information of PA health benefits beyond weight control might help encourage behavior change.