The impact of social influence on physical activity among adolescents - a longitudinal study

Objectives: The purpose of the current study was to examine the impact of social support and negative social influence from various contexts on adolescents' current and intended physical activity (C&IPA) two years later. In addition, social influence related to C&IPA at baseline (1617 years old) is compared to follow-up (1819 years old). Methods: Questionnaire data was obtained from 404 students at the age of 1617 and again at the age of 1819. Relationships among variables were examined with structural equation modelling (SEM). Results: Social influence experienced by high-school students at 1617 years of age had a direct suppressing effect and an indirect positive effect on their C&IPA two years later. Social support for physical activity was more complex and related to positive as well as negative relations at the age of 1617 compared to two years later. Conclusions: The results imply that social support to adolescents should be offered over a longer period of time, with increased focus on its significance as a link from an initially external regulation to a more internal regulation of physical activity as students get older. Closer examination of maintaining, pro-activating and intervening effects of social support could enhance our understanding of direct and indirect effects of social support on physical activity.