Application of the Social Cognitive theory to predict stages of change in exercise for Brazilian adolescents

Resumen

Adolescence is characterized by a peak decline in physical activity levels. Psychological theories, such as Social Cognitive Theory and the Transtheoretical Model have been applied in order to explain the regularity of youth physical activity adherence. These theories, however, are rarely applied to study physical activity behavior in Brazilian adolescents. Therefore, the purpose of the present study was to examine personal, behavioral and environmental characteristics associated with different stages of exercise behavior among a sample of Brazilian adolescents. The participants were 488 high-school students (57.5% boys) with ages ranging from 14 to 17 years. Valid and reliable instruments were used to measure self-reported physical activity, social cognitive variables and also stages of change in exercise behavior. Multivariate discriminant analyses and One-Way ANOVA were performed to identify associations among these variables and stages of change. Self-efficacy was a significant predictor (p<0.001) for boys and girls while family social support was a predictor only for boys (p<0.001). Moderate to vigorous physical activity was consistently associated with stages of change in boys and girls (p<0.001). There was an irregular pattern of centroid differences which indicated that girls move from pre-contemplation to maintenance stage in a clearer pattern than boys and boys move along fewer stages compared to girls. Although social cognitive variables predicted stages of change in exercise behavior, the source of social support differed for boys and girls.