Associations between daily intentions and physical activity among adolescent girls: the moderating role of multi-level factors

Abstract

Notable decreases in physical activity (PA) occur across adolescence, especially among girls, yet the most developmentally salient determinants of PA among adolescent girls are widely unknown. Although the role of a youth's daily intentions to engage in PA is established, little research has examined how individual, social, and environmental factors, within the context of one another, may influence this association in adolescent girls' daily lives. Adolescent girls ( N = 66; 12–18 years) completed a 28-day daily diary study. Each morning girls reported their PA intentions for that day. Each night girls reported their perceived affect, social support for PA, perceptions of their environment (i.e., safety, aesthetics, PA resources, walkability), and PA for that day. Within- and between-person associations were assessed with multilevel models. On days when girls reported higher positive affect than was typical for them (within-person), the association between intentions and PA was stronger compared to days when they reported lower positive affect than was typical ( B = 0.01, p < 0.05, 95% CI : 0.001, 0.02). On days when girls reported higher social support for PA ( B = 0.78, p < 0.001, 95% CI : 0.55, 1.00) and had more positive perceptions of their environments ( B = 0.44, p < 0.05, 95% CI : 0.14, 0.75) than was typical for them, they tended to report more PA. Results suggest that the association between daily intentions and adolescent girls' PA is influenced by within-person differences in positive affect, above and beyond the influences of daily fluctuations in individual, social, and environmental factors.