Repeatability of self-report measures of physical activity, sedentary and travel behaviour in Hong Kong adolescents for the iHealt(H) and IPEN - Adolescent studies.

Background: Physical activity and sedentary behaviour are important contributors to adolescents' health. These behaviours may be affected by the school and neighbourhood built environments. However, current evidence on such effects is mainly limited to Western countries. The International Physical Activity and the Environment Network (IPEN)-Adolescent study aims to examine associations of the built environment with adolescent physical activity and sedentary behaviour across five continents.We report on the repeatability of measures of in-school and out-of school physical activity, plus measures of out-of-school sedentary and travel behaviours adopted by the IPEN - Adolescent study and adapted for Chinese-speaking Hong Kong adolescents participating in the international Healthy environments and active living in teenagers-(Hong Kong) [iHealt(H)] study, which is part of IPEN-Adolescent.

Methods: Items gauging in-school physical activity and out-of-school physical activity, and out-of-school sedentary and travel behaviours developed for the IPEN - Adolescent study were translated from English into Chinese, adapted, and pilot tested. Sixty-eight Chinese-speaking 12-17 year old secondary school students (36 boys; 32 girls) residing in areas of Hong Kong differing in transport-related walkability were recruited. They self-completed the survey items twice, 8-16 days apart. Test-retest reliability was assessed for the whole sample and by gender using one-way random effects intra-class correlation coefficients (ICC). Test-retest reliability of items with restricted variability was assessed using percentage agreement.

Results: Overall test-retest reliability of items and scales was moderate to excellent (ICC = 0.47-0.92). Items with restricted variability in responses had a high percentage agreement (92%-100%). Test-retest reliability was similar in girls and boys, with the exception of daily hours of homework (reliability higher in girls) and number of school-based sports teams or after-school physical activity classes (reliability higher in boys).

Conclusions: The translated and adapted self-report measures of physical activity, sedentary and travel behaviours used in the iHealt(H) study are sufficiently reliable. Levels of reliability are comparable or slightly higher than those observed for the original measures.