Physical Activity Mitigates the Impact of Chronic Stress on BMI growth in Girls from ages 10 through 19: Results from the NHLBI Growth and Health Study

Obesity is a striking contributor to chronic disease development and is emerging earlier in life. Therefore, understanding factors that contribute to obesity in youth is essential for prevention. While lifestyle factors influence obesity trends, chronic stress is emerging as an important feature in body mass index (BMI) changes during childhood. The current study examines whether physical activity moderates stress effects on BMI in girls transitioning to young adulthood. We utilized data from the NHLBI Growth and Health Study, a study with 1,209 black and 1,166 white girls aged 9-10, and followed yearly until age 19. Measures included psychological stress (Perceived Stress Scale, Cohen, 1984), physical activity (Habitual Activity Questionnaire, Ku, 1981), height, and weight. Covariates included parental education, race, and calorie consumption. Results with growth curve modeling indicated significant linear increases in BMI over the course of 10 years. As reported elsewhere, chronic stress over the course of the ten years significantly contributed to BMI growth (p < .001). In the current analyses, chronic stress effects on BMI was significantly mitigated by physical activity (p = .007). High-stressed less active girls increased by 1.98 BMI units every two years, on average, but high-stressed active girls increased by 1.65 units. Low-stressed less active girls increased by 1.76 units, and low-stressed active girls only by 1.41 units. These effects were consistent across race. Our study clearly directs attention to maintaining physical activity regimens during the critical growth period from childhood to adulthood, especially in chronically stressed girls.