Features of the built environment related to physical activity friendliness and children's obesity and other risk factors.

OBJECTIVES: We investigated the relationships among environmental features of physical activity friendliness, socioeconomic indicators, and prevalence of obesity (BMI status), central adiposity (waist circumference, waist-height ratio), and hypertension. DESIGN AND SAMPLE: The design was cross-sectional; the study was correlational. The sample was 911 kindergarteners through sixth graders from three schools in an urban school district residing in 13 designated neighborhoods. MEASURES: Data from walking environmental community audits, census data for socioeconomic indicators, body mass index, waist circumference, waist-height ratio, and blood pressure were analyzed. A modified Alfonzo's Hierarchy of Walking Needs model was the conceptual framework for environmental features (i.e., accessibility, safety, comfort, and pleasurability) related to physical activity. RESULTS: Accessibility was significantly and negatively correlated with prevalence of obesity and with prevalence of a waist-height ratio >0.50. When neighborhood education was controlled, and when both neighborhood education and poverty were controlled with partial correlational analysis, comfort features of a walking environment were significantly and positively related to prevalence of obesity. When poverty was controlled with partial correlation, accessibility was significantly and negatively correlated with prevalence of waist-height ratio >0.50. CONCLUSIONS: The built environment merits further research to promote physical activity and stem the obesity epidemic in children. Our approach can be a useful framework for future research.

Overweight and central adiposity in school-age children and links with hypertension.

The purpose of this study of school-age children was to estimate prevalence and interrelationships of overweight, central adiposity, and hypertension. It included 1,070 children in kindergarten through sixth grade (67% Hispanic, 26% African American, mean age = 8.9 years). Measures included body mass index (BMI), waist circumference (WC), systolic and/or diastolic hypertension identified by measurements on three separate occasions. Percentage overweight (BMI >or=95th percentile) was 28.7%, 17.9% were at risk of overweight, 28.8% had WC >or=90th percentile, and 9.4% had elevated (>or=90th percentile) systolic and/or diastolic blood pressure (BP). If we had screened only for BMI and examined those with BMI >or=85th percentile or underweight for hypertension, we would have missed 26% of the children with persistently elevated BP. WC explained variance in elevated BP not explained by BMI (p < .001). Measurement of WC is easily incorporated in a school-based screening protocol.

The cost of screening adolescents for overweight and hypertension using a community partnership model.

OBJECTIVES: (1) Determine the prevalence of overweight and high blood pressure (BP) among middle and high school students over a 2-year period and, (2) measure the cost and initial outcomes of screening. DESIGN: Cost and outcome description using a cross-sectional design sample. The target population was 12- to 19-year-old healthy students attending grades 7 through 12 at 3 proximal schools located in a large urban school district in Texas. RESULTS: Of 2,338 students screened, 925 (39.6%) had a body mass index (BMI)>or=85th percentile and 504 (21.6%) had BMIs>or=95th percentile for age and gender. There were 346 students (14.8%) with BMIs>or=85th percentile and systolic blood pressure (SBP)>or=95th percentile for age, gender, and height. The cost of the 2-year screening program was $66,442, and the cost per student was $28. The cost to identify a student with increased BMI or high SBP was $72 and $107, respectively. CONCLUSIONS: This study offered an objective framework to examine the cost and outcomes of screening children for overweight and increased BP. The study has implications for discussion and informed decision making about school-based screening for these conditions.

The relationship of ambulatory blood pressure to physical activity in a tri-ethnic population of obese and nonobese adolescents.

BACKGROUND: The association between physical activity (PA) and ambulatory blood pressure (ABP) is documented in adults. This association and factors that may modify it, such as obesity, have not been reported in adolescents. The aims of this study were to determine the association of PA with ABP in 11- to 16-year-old adolescents, and to examine the modifying effects of obesity and other factors. METHODS: Data on 24-h ABP and PA were obtained from 374 adolescents using the wrist actigraph. Correlations between average PA for every 5-min interval preceding each BP measurement and ABP were calculated during the awake period. Mixed-effects models were used with ABP variables as separate, dependent variables. In addition to PA scores for 5 min preceding each BP, body mass index (BMI) z-score and other variables were added to the models as covariates and as interaction terms with activity. RESULTS: Correlations of PA for 5 min preceding BP measurements were 0.22 and 0.25 for systolic blood pressure (SBP) and diastolic blood pressure (DBP) respectively. In mixed-effects analysis, each 1-unit increase in PA was associated with an increase in SBP of 0.02 mm Hg, in DBP of 0.01 mm Hg, and in HR of 0.02 beat/min (P < .0001). The association of BP with PA was significantly less for those with higher BMI z-scores (SBP, P < .001, DBP, P = .027). The associations of PA with SBP and HR were modified by sexual maturation status of the adolescents. CONCLUSIONS: This study found that PA is associated with ABP measurements. These associations are modified by obesity status and other variables. Recognizing these associations may improve the interpretation of ABP measurements.

Sleep duration and its association with ambulatory blood pressure in a school-based, diverse sample of adolescents.

BACKGROUND: Evidence is accumulating that sleep duration is related to blood pressure (BP) and hypertensive status, but the strength of the association varies by age, and findings are inconsistent for adolescents. This cross-sectional study tested the hypothesis that sleep duration, both during the night and during naps, would be negatively associated with ambulatory systolic BP (SBP) and diastolic BP (DBP) measured over 24 hours in adolescents. METHODS: In this ethnically diverse (37% non-Hispanic black, 31% Hispanic, 29% non-Hispanic white, 3% other), school-based sample of 366 adolescents aged 11-16 years, ambulatory BP was measured every 30 minutes for 24 hours on a school day; actigraphy was used to measure sleep duration. Covariables included demographic factors, anthropometric indices, physical activity, and position and location at the time of each BP measurement. Mixed models were used to test day and night sleep duration as predictors of 24-hour SBP and DBP, controlling for covariables. RESULTS: The mean sleep duration was 6.83 (SD = 1.36) hours at night, and 7.23 (SD = 1.67) hours over 24 hours. Controlling for duration of sleep during the day and covariables, each additional hour of nighttime sleep was associated with lower SBP (-0.57; P < 0.0001); controlling for nighttime sleep duration and covariables, each additional hour of daytime sleep was associated with lower SBP (-0.73; P < 0.001) and lower DBP (-0.50; P < 0.001). CONCLUSIONS: Longer sleep duration was significantly associated with lower ambulatory SBP and DBP in adolescents. The findings have potential implications for cardiovascular health in this age group.