Examining The Role Of Physical Activity, Cardiovascular Fitness, And Neighborhood Stress On BMI And Waist Circumference

Abstract

Childhood obesity is a significant risk factor for a number of common health conditions that may persist into adulthood. Neighborhood stress is associated with decreased physical activity (PA) and adiposity. PA is a potential health behavior protector that may attenuate the effects of chronic stress. However, the moderating effect of PA and/or cardiovascular fitness (CVF) on the relationship between stress and adiposity is not clearly defined. PURPOSE: To examine the effect of PA and/or CVF on the relationship between stress, BMI, and waist circumference among adolescent females. METHODS: Baseline data were obtained from ninth grade girls (n=213, 83% African American, 14% Caucasian) enrolled in a randomized PA intervention trial. PA was assessed using an interviewer-administered 7-day physical activity recall to calculate relative daily caloric expenditure. CVF was estimated from a three stage progressive step test. Mean heart rates from Stage 1 of the fitness test were analyzed. Height and weight were measured to assess BMI (kg/m2). Abdominal adiposity was estimated through waist circumference (WC) measurement. Perceived neighborhood stress was assessed via a 36-item, City Stress Inventory (CSI) and mother's education level was used as a surrogate measure to assess SES. RESULTS: 45% of participants (25.07+ 6.8) were classified as overweight or obese, according to Cole et al. BMI cutoff points. 15.4% of African American (69.3+11.2) and 22.6% of Caucasian (69.6+9.5) girls were above the 75th percentile for WC. In order to control for age, ethnicity and SES, hierarchical regression analysis was conducted. Results of the analysis revealed significant main effects for CSI on WC (ΔR2=.02, p=.048) and BMI (ΔR2=.03, p=.023) as well as significant main effects for PA and CVF on WC (ΔR2=.76, p<.01) and BMI (ΔR2=.86, p<.01). However, interactions between PA, CVF, and CSI were not significant. CONCLUSIONS: CSI is significantly associated with BMI and waist circumference but PA or fitness does not appear to moderate this association. Additional work is needed to determine cause and effect relationships and how this association may be attenuated. This study was supported by RO1 HL63861