Effects of body mass and body image on exercise motives in adolescence

Abstract

Objective. The objective was to examine age and gender differences in the effects of body mass and body image on exercise motives in adolescents. It was specifically predicted that weight management motive would be explained by body mass index in males, and by body size discrepancy in females, but this pattern would be less pronounced in younger than in older adolescents. Design. The design was a cross-sectional comparative study. Method. Participants comprised younger (11–13 years) and older (17–19 years) males and females (N=180). They completed measures of exercise participation, exercise motives, and perceived and ideal body size. Height and weight were also measured. Hierarchical regression analyses were conducted, separately for younger males, younger females, older males and older females. In each analysis, the dependent variable was an exercise motive, and the independent variables were, in order of entry, exercise level, body mass index, perceived body size, and ideal body size. Results. Weight management motive was positively predicted by body mass index in older males, and by perceived and ideal body size in older females. Other, more intrinsic, motives were negatively predicted by body mass index or perceived body size in older males or females. Such relationships were not significant in younger adolescents. Conclusion. Effects of body mass and body image on exercise motives emerge in adolescence, with gender differences. Such effects may influence exercise adherence and should be taken into account in exercise promotion programmes.