Methods
Study Participants and Method of Selection
For this cross-sectional descriptive study, a school-based health screening was performed on 1,284 students in grades five through eight from ten schools in three different school districts in rural northern California. Participating schools represent a variety of ethnicities reflective of the ethnic make-up of the geographical area. Only those students who returned a signed parental permission slip were able to participate. This research was approved by the California State University, Chico Human Subjects Committee.
Data Collection Instrument and Procedures
A lifelong eating and activity patterns questionnaire was used to collect information on gender, ethnicity, and date of birth, as well as several questions and Likert statements concerning dietary consumption and physical activity levels. The survey questionnaire was field-tested for face and content validity and refined based on the results of this field-test. Trained researchers provided assistance and clarification to the students during the completion of the lifelong eating and activity patterns questionnaire when needed.
Height and weight were measured by trained researchers for each student and BMI (kg/ht2) was then calculated. The scale used was a standard medically approved dial scale with weight measured to the nearest whole pound. Height was measured with a standiometer and reported in inches to the nearest quarter inch. BMI percentile, age and gender specific, was determined using the most current pediatric anthropometric reference data (Kuczmarski, Ogden, Grummer-Strawn, 2000). Overweight is defined by the CDC as BMI-for-age >95th percentile and at-risk for overweight is defined as BMI-for-age >85th percentile.
A trained researcher or school nurse took blood pressure measurements. Blood pressure was taken while the participants were seated and after the completion of the questionnaire to assure that heart rate was at a resting rate. Three different sized cuffs were available for use, with the appropriate sized cuff being utilized for each participant. If the blood pressure reading was elevated, the measurement was repeated a second time. HTN is defined as systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) >95th percentile for age, gender, and height measured on three distinct occasions. Pre-HTN is defined as SBP and/or DBP between the 90th and 95th percentiles for age, gender, and height (NHLBI, 2004).
Statistical Analysis
Data were analyzed using the Statistical Package for the Social Sciences (version 11.0, 2001, SPSS, Inc, Chicago, IL). Descriptive statistics are presented as counts, percentages, and means + standard deviations. Chi square was used to examine differences between groups for a variety of selected variables. An independent samples t -test was used to assess for significant differences in mean BMI for students consuming greater than two sodas per day vs. those consuming less than two sodas per day. Analysis of variance (ANOVA) was used to test for differences in BMI and blood pressure based on fruit, vegetable, and soda consumption and physical activity patterns. Pearson