healthscotland.com

Sedentary behaviour among Scottish youth: prevalence and determinants

Summary

1. There is a great deal of concern about young people’s overweight and obesity. Sedentary lifestyles are thought to be particularly important in weight gain yet it is common in the popular media and academic literature to simplify matters by stating that electronic media, such as the television and computer games, are primarily the cause of a ‘couch kids’ culture.
2. Project STIL (‘Sedentary Teenagers and Inactive Lifestyles’) at Loughborough University is research focusing on a wide range of sedentary and physically active behaviours. Project STIL (Scotland) investigated a Scottish sample with the dual purpose of a) obtaining estimates for the prevalence of sedentary behaviour in Scottish youth, and b) investigating factors associated with sedentary behaviour.
3. The principal data collection instrument was a self-report diary of “free-time” behaviours that school students completed outside of school hours (3 weekdays and 1 weekend day). The diary asked the participants to write down what they were doing at 15-minute time intervals. In addition, they recorded where they were. Demographic variables were also assessed.
4. Assessment took place in 27 schools from 14 local education authorities. Data were collected in two phases: October-November 2002 and February-May 2003 with school Years S2-S4 (ages 13-15 yrs). The final sample comprised 396 boys and 620 girls (total n=1016).
5. Boys averaged just over 2hrs TV viewing per day during the week and 3hr and 15mins at weekends; boys in Year S4 watched less TV than those in Years S3 and S2. Girls averaged just under 2hrs of TV viewing per day during the week and 2hr and 39mins at weekends; girls in Year S2 watched more TV than those in Years S3 and S4.
6. Other prominent sedentary behaviours included motorised travel, computer use, homework, and ‘hanging out’ with friends.
7. Boys were markedly more active than girls in sports and exercise
8. Results were minimally affected by ethnicity and socio-economic status.
9. Relationships between TV viewing and physically active behaviours were very small.
10. After school, there was a slight shift in likelihood of behaviour from motorised to active travel compared to before school, suggesting that active travel is possible for some children who use motorised means of travel to school.
11. The greatest likelihood of playing sport and exercise during the school week was in the early evening, whereas the likelihood of watching TV peaked later, suggesting some temporal displacement between the two behaviours.
12. There was never a time during the week when sports and exercise were more likely than TV viewing, but sports and exercise were more likely during periods of the weekend day for boys.
13. TV viewing was no greater for those with TV sets in their bedroom than those without, although for those with TVs in their bedroom, there was a 26% chance of watching TV, when in the bedroom, for girls and 35% for boys during the week, and at weekends 40% for boys and 29% for girls.
14. Physical activity was an inverse predictor of a cluster of sedentary behaviours, and the prediction was enhanced by accounting for the time young people spent outside. Interventions should focus on increasing opportunities for time outside of the house, requiring a mix of initiatives, ranging from structured activities, such as some sports, to environmental modifications based on attractiveness, accessibility, and safety.
15. While high and low TV viewing groups do differ in the amount of sports and exercise and time outside, the effect sizes are small-to-moderate.
16. When considering high and low sedentary groups, the amount of sports and exercise and time outside show much greater differences, all revealing large effect sizes. This confirms our view that while TV viewing is a prevalent sedentary behaviour, it is a not a good marker of total sedentary behaviour. Interventions might be better targeted at a profile of several sedentary behaviours rather than TV alone, as well as time spent outside.
17. Using cluster analysis, diverse groupings across sedentary and active behaviours were found for both boys and girls. This suggests that no one sedentary behaviour is likely to be an effective intervention target for the majority of adolescents. In addition, the clusters confirmed that TV viewing is not necessarily in opposition to sports and exercise.