Targeting change in physical activity and screen time behaviours within the HEalth In Adolescents (HEIA) intervention study: A mediating framework approach

Abstract

During the 1990’s and early 2000’s there has been an increase in prevalence of overweight (including obesity) in European children and adolescents. This is a public health challenge as overweight and obesity are associated with adverse psychosocial and physiological health effects, both in youth and adulthood. School-based interventions to promote physical activity, improve dietary and reduce sedentary behaviours have been recommended for weight regulation. However, only modest and mixed effects of obesity prevention initiatives have been seen so far. This may, however, be due to ineffective targeting of potentially mediating variables of the behaviours assumed to influence weight development or insufficient implementation of the interventions. Aim The overall goal of the HEalth in Adolescents (HEIA) study was to design, implement and evaluate a comprehensive intervention programme to promote healthy weight development among young adolescents (11 to 13 year-olds). Change in weight development was targeted through change in physical activity, sedentary and dietary behaviours. This thesis investigates: 1) modifiable correlates of moderate-to-vigorous physical activity (MVPA) at baseline; 2) intervention effect on targeted determinants hypothesized to mediate change in physical activity and screen time behaviours; 3) how adolescents’ reported “dose received” of the intervention was related to change in these determinants, and 4) mediating effects of the targeted determinants on physical activity and screen time behaviour change, as well as main effect on screen time behaviours. In addition, moderation effects of gender, weight status, and parental education status were explored.

Paper Ia: Tatt ut av filen i Brage p.g.a. copyright-restriksjoner. / Not in the file in Brage because of copyright issues.

Paper Ib: Bergh IH, Grydeland M, Bjelland M, Lien N, Andersen LF, Klepp K-I, Anderssen SA, Ommundsen Y. Personal and social-environmental correlates of objectively measured physical activity in Norwegian pre-adolescent children. Scandinavian Journal of Medicine & Science in Sports 2011.

Paper II: Bergh IH, Bjelland M, Grydeland M, Lien N, Andersen LF, Klepp K-I, Anderssen SA, Ommundsen Y. Mid-way and post-intervention effects on potential determinants of physical activity and sedentary behavior, results of the HEIA study - a multi-component school-based randomized trial. International Journal of Behavioral Nutrition and Physical Activity 2012, 9:63.

Paper III: Bergh IH, van Stralen MM, Grydeland M, Bjelland M, Lien N, Andersen LF, Anderssen SA, Ommundsen Y. Exploring mediators of accelerometer assessed physical activity in young adolescents in the HEalth In Adolescents study – a group randomized controlled trial. BMC Public Health 2012, 12:814.

Paper IV: Bergh IH, van Stralen MM, Bjelland M, Grydeland M, Lien N, Klepp K-I, Anderssen S, Ommundsen Y. Post-intervention effects on screen behaviours and mediating effect of VIII parental regulation: the Health in Adolescents (HEIA) - a multi-component school-based randomized trial (BMC Public Health, submitted)