Reliability and validity of a single-item physical activity measure for adolescents

Aims: The aim of this study was to examine the test-retest reliability and concurrent validity of an adolescent single-item physical activity measure by comparing it with the existing Oxford Physical Activity Questionnaire (OPAQ) and accelerometer output. Methods: Participants were 123 adolescents (14.7 +/- 0.5 years) from three secondary schools in New South Wales, Australia. To determine reliability, participants completed both questionnaires on two occasions separated by 2 weeks. To assess validity, participants wore Actigraph GT3X+ accelerometers for a 7-day monitoring period and completed both physical activity questionnaires. Bivariate correlations between self-reported moderate-to-vigorous physical activity (MVPA) and accelerometer MVPA min/day were calculated. Results: The single-item (intra-class correlation coefficient (ICC) = 0.75, 95% confidence interval (CI) = 0.64-0.83, P < 0.001)) and the OPAQ (ICC = 0.79, 95% CI = 0.69-0.86, P < 0.001) were both found to have moderate-to-strong reliability. Correlations between self-reported and objectively measured MVPA were similar for the single-item measure (r = 0.44, 95% CI = 0.24-0.63, P < 0.001) and the OPAQ (r = 0.50, 95% CI = 0.30-0.65, P < 0.001). Conclusions: These findings suggest the single-item measure can provide a reliable and valid assessment of youth physical activity.