Obesity and Physical Fitness in California School Children

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Obesity and Physical Fitness in California School Children

Methods


In 1996, the CDE designated a Physical Fitness Test (PFT) called the "Fitnessgram" as the required physical performance test to be administered to all 5th, 7th, and 9th graders in California on an annual basis to assess the prevalence and development of overweight, obesity, and overall physical fitness in school children. The Fitnessgram was developed by the Cooper Institute for Aerobics Research in Dallas, Texas, and endorsed by the American Alliance for Health, Physical Education, Recreation, and Dance. The Fitnessgram was designed to assess different fitness categories such as cardiovascular fitness, body composition, muscle strength, muscle endurance, and flexibility.

In 2004, a multidisciplinary commission on Childhood Obesity, Type 2 Diabetes, and Cardiovascular Disease was appointed by the superintendent of the CDE to review Fitnessgram data and consider recommendations. These recommendations were incorporated into the CDE code. Subsequently, legislation was introduced in the California Senate (SB12 and 965) and became law in 2005.

As a result, the following task force recommendations were implemented in all public schools in California: (1) Increase physical exercise to a minimum of 200 minutes for grades K to 5 and 400 minutes for grades 6 to 12 averaged over 10 days. (2) Increase health education to promote healthful eating and physical activity. (3) Ensure the serving of healthy foods and beverages at school and prohibit high-fat, high-sugar foods and beverages. Regular audits to ensure that schools complied with the above-mentioned requirements were scheduled. The annual Fitnessgram performed by all 5th, 7th, and 9th graders would then serve to monitor any changes in obesity and fitness associated with the implementations of the task force, CDE code, and state law changes.

The Fitnessgram test is comprised of the following 6 major fitness areas with one or more performance task options for each area, so that all students, including those with special needs, have the opportunity to participate in the tests. The "healthy fitness zones" (HFZs) as defined in the Fitnessgram are age-adjusted research-based standards for body composition, aerobic capacity, muscular strength, and flexibility.

Body Composition


Skin Fold Measurements Skin fold measurements on the back of the upper right arm and the inside of the right calf are taken using a skin fold caliper. Measurements are converted to percentages of body fat by using a body composition (BC) conversion chart provided in the Fitnessgram Test Administration Manual.

Body Mass Index This test provides an indication of a student's weight relative to his or her height. Although not as accurate an indicator of BC as the skin fold measurements, schools find this measurement less of a parent concern than skin fold measurements.

Bioelectric Impedance Analyzer The bioelectric impedance analyzer (BIA) measures resistance to the flow of an electrical signal in the body. The resistance, along with other values such as height, weight, age, and gender, is then used to estimate body fat.

Aerobic Capacity


Progressive Aerobic Cardiovascular Endurance Run This is a multistage fitness test set to music, which provides a valid alternative to the customary distance run. Students run as long as possible back and forth across a 20-meter distance at a specified pace that gets faster each minute.

One-mile Run Students walk and/or run a distance of one mile at the fastest pace possible. Walking is permitted for students who cannot run the total distance. The time taken to complete the run is recorded in minutes and seconds.

Walk Test Students walk a distance of one mile as quickly as possible while maintaining a constant walking pace for the entire distance. This test is only for students who are 13 years and older.

Abdominal Strength


Curl-up As many curl-ups as possible up to a maximum of 75 have to be completed at Fitnessgram-recorded cadences.

Trunk Extensor Strength


Trunk Lift The upper body has to be lifted from a prone position to a maximum of 12 inches off the floor using the muscles of the back.

Upper Body Strength


Push-up As many push-ups as possible have to be completed at Fitnessgram-recorded cadences.

Pull-up Students are required to correctly complete as many pull-ups as possible.

Modified Pull-up As many modified pull-ups as possible have to be performed. The modified pull-up is different from a pull-up in that students perform the test by lying on their back directly under a bar and grasping the bar to pull-up.

Flexed-arm Hang The students hang by the arms with the chin above a bar as long as possible.

Flexibility


Back-saver Sit and Reach The test assesses the flexibility of the lower back and posterior thigh.

Shoulder Stretch Upper body flexibility is tested by trying to touch the fingertips of both hands together behind the back by reaching over both the right and left shoulder and under the elbow.

Pauses and rest periods are not allowed while taking any of the exercise fitness tests.

The Fitnessgram uses age-adjusted, criterion-referenced standards to evaluate fitness performance. These standards were established to represent a level of fitness that offers some degree of protection against diseases that result from sedentary lifestyle. The reliability and validity of the measurements used in the Fitnessgram have been described in detail.

Performance levels for each of the Fitnessgram tests were classified as "in Healthy Fitness Zone" (HFZ) or "needs improvement." The desired performance goal for each fitness area test was in the HFZ. For each student, the number of fitness areas in which the HFZ had been achieved was summed to provide an overall composite score (0–6).

The Fitnessgram was administered by specially trained employees of the school district (teachers, or employees from the county office of education). Every school district designated a Fitnessgram coordinator to supervise and transfer the collection of all data in the school district to the state Fitnessgram contractor.

Statistical Analysis


Individual data from every student was requested from the CDE for statistical analysis at the student level between 2003 and 2008.Our preliminary analysis was targeted to reveal changes in BC, aerobic capacity (AC), abdominal strength (AS), upper body strength (UBS), trunk extensor strength (TES), and flexibility over the last 5 years. The general linear model for analysis of variance was used for subgroup comparison of changes in body mass index (BMI) over time. We applied CDC (Center for Disease Control) age-adjusted standards to identify if a student was overweight or obese, and used a multivariable logistic model to identify marginal effects of gender, grade, and race/ethnicity controlling for the year of test performed.

The fitness data analysis was restricted to students who completed all fitness tests. For each fitness indicator as the response variable, we created a HFZ measure for fitness using an all-or-none approach. This defined students as in HFZ for each of the 6 fitness indicators. We applied the Cochran-Armitage trend test to examine if the statewide changes in proportion of students in HFZ were statistically significant over time between 2003 and 2008 and serially within each entrance class. Student gender, grade (5th, 7, and 9th), race/ethnicity, and region were used for a classification of subgroups, and the same trend test was performed separately for each subgroup. Differences were considered significant if P < .05. Multivariable logistic regression models were developed for each indicator of physical fitness and the composite HFZ measure to identify the impact of region, gender, grades, race/ethnicity, median county-wide income, and county-wide employment rates while controlling for the year of tests performed. Overall composite HFZ (0–6 fitness criteria) was evaluated between 2003 and 2008.

All data analyses were conducted using SAS version 9.2 (SAS Institute, Cary, NC).

The authors are solely responsible for all study analyses, the drafting and editing of the paper and its final contents. No extramural funding was used to support this work.

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