Age, Physical Activity Motivation and Perceived Stress in Minority Girls.

Background: Physical activity in childhood and adolescence helps support physical and emotional health.

Purpose: The study aimed to investigate if age was related to motivation for physical activity in minority girls, and whether the relationship may be potentially mediated by psychological or physiological stress.

Methods: This cross-sectional observational study recruited Latino and African American girls ages 8 - 12 years (n = 79) in Tanner stage 1 or 2 via purposive sampling. Intrinsic motivation and perceived stress were measured by self-report survey; morning salivary cortisol samples were taken to calculate cortisol awakening response to estimate biological stress reactivity.

Results: Increased age was related to higher intrinsic motivation to engage in physical activity. Lower perceived stress and lower awakening cortisol response were associated with higher intrinsic motivation. Bootstrapped mediation results indicated perceived stress may be a pathway through which age impacts intrinsic motivation for physical activity.

Conclusion: While motivation to engage in physical activity may increase with age, perceived stress may dampen this motivation, resulting in decreased physical activity. Interventions to help increase pre-adolescent girls' engagement in active behaviors may benefit from reducing children's perceptions of stress.