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The purpose of this study was to describe the relationships between Social Cognitive Theory (SCT) variables and frequency of moderate-vigorous physical activity in a sample of high school students. Days of moderate and vigorous physical activity were assessed using a previously validated one-day recall instrument administered on seven consecutive days. The SCT variables tested were: self-regulation, social situation, social outcome expectations, physical appearance outcome expectations, general health outcome expectations, negative outcome expectations, self-efficacy for ability, and self-efficacy for barriers. The SCT variables studied are potentially modifiable via educational interventions. Results revealed that 15 % of the subjects reported 3 or more days of physical activity. Four of the SCT were retained in the regression model accounting for 31 % of the variance in days or moderate-vigorous physical activity. SCT is useful for understanding frequency of moderate-vigorous physical activity among adolescents.

Obesity is a major health problem in the U.S., especially for Hispanic youth. Because maximal/peak oxygen consumption (V.O (2)peak) is one predictor of future weight gain in children, valid field-based methods for determining V.O (2)peak in Hispanic children are needed. The purpose of this study was to validate a field-based aerobic fitness test, the 20-m shuttle test (20-MST), in Hispanic boys (n = 58) and girls (n = 67), 10 - 12 years old (mean age +/- SD, 10.7 +/- 0.6 y). Measured V.O (2)peak was determined during a maximal, graded treadmill test using the Bruce protocol. The 20-MST was administered per a standard protocol. Maximal speed attained on the 20-MST and age were used to estimate V.O (2)peak. An intraclass coefficient of 0.82 was obtained on 35 students (16 boys; r = 0.85 and 19 girls; r = 0.79) who completed the 20-MST twice, 1-wk apart. Estimated (44.3 ml x kg (-1) x min (-1) ) and measured (45.1 ml x kg (-1) x min (-1)) V.O (2)peak were not significantly different (p = 0.33). The correlation between the two V.O (2)peak parameters was r = 0.62; p < 0.001, the standard error of the estimate (SEE) was 3.91 ml x kg (-1) x min (-1), and 85.5 % of the measured V.O (2)peak values fell within 5.9 ml x kg (-1) x min (-1) of estimated V.O (2)peak. The weight status of the child did not significantly change these results. The 20-MST combined with the Leger et al. equation is a valid method for predicting V.O (2)peak in Hispanic youth. The test can be used to provide valuable information for intervention design and disease prevention.

OBJECTIVE: To describe the problem of obesity in Mexican American children and provide a method for identifying Mexican American children at risk for obesity. DESIGN: Cross-sectional and retrospective cohort study. SUBJECTS: Mexican American children, ages 5 ± 11 (kindergarten (K) ± 5th grade) were studied in cross-sectional (girls 463, boys 448) and retrospective (girls 124, boys 92) samples. MEASUREMENTS: Weights (kg) and heights (cm) were extracted from each child's school medical records. Measurements were made by the school nurses (one nurse per school). Body mass index (BMI [wah 2 ]) was calculated from obtained weights and heights. RESULTS: The prevalence of obesity in the cross-sectional sample was 27.4% for girls and 23.0% for boys. The highest prevalence was noted in 4th grade for both the girls (32.4%) and boys (43.4%). The 5 year incidence rates derived from the retrospective sample were 17.7% for girls and 21.1% for boys. The largest increase in the number of girls becoming obese was observed between K and 1st grade (15.6%). The largest increase for boys was found between the 1st and 2nd grades (13.2%). Logistic regression parameters were calculated to estimate the probability of becoming obese in 5th grade given a child's K BMI. Using the generated equation, BMIs in K equal to 16.5, 20.9, and 23.7 would have a 21.0%, 70.0%, and 91.0% probability of being obese by 5th grade. CONCLUSION: This study provides schools with a simple procedure for identifying Mexican American children at risk for obesity. This procedure may assist in the development and implementation of interventions aimed at averting the onset of obesity in this population.

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