Promoting physical activity and a healthful diet among children: results of a school-based intervention study.

BACKGROUND: National health objectives call for improved diet and more regular physical activity among children. We tested the effects of a school-based program to improve students' diet and physical activity behavior at school. METHODS: Two of the four elementary schools in one Texas school district were assigned to intervention and two to control conditions. The three intervention components were classroom health education, vigorous physical education, and lower fat, lower sodium school lunches. Nutrients from school lunches and the total day and the amount of physical activity students obtained during physical education were assessed as outcome. RESULTS: Analysis of school lunches showed declines from base line to posttest in the two intervention schools of 15.5% and 10.4% for total fat, 31.7% and 18.8% for saturated fat, and 40.2% and 53.6% for sodium; posttest values were lower in the intervention schools. Observation of physical activity during physical education classes indicated an increase in the intervention schools from baseline to posttest in the percent of time children engaged in moderate-to-vigorous physical activity from less than 10% of class time at baseline to about 40% of class time at posttest; posttest values were higher in the intervention schools than in the control schools. CONCLUSIONS: This efficacy study demonstrates the feasibility of substantially modifying school lunches and school physical education to improve children's diet and physical activity behavior at school.

Children's frequency of participation in moderate to vigorous physical activities.

Third and fourth grade boys (n = 422) and girls (n = 390) in four Texas elementary schools reported their participation in moderate to vigorous physical activities (MVPAs) over a 3-day period. Students were surveyed during class on successive days. On a subsample (n = 44), the agreement between reported and observed physical activities during physical education or recess was 86.3%. Running, walking fast, games and sports, and bicycling accounted for 70% of Total MVPAs. Of Total MVPAs reported, 47.0% for boys and 44.6% for girls were 10 min or longer in duration (LMVPA). The average number of LMVPAs per day was 1.7 for both boys and girls. Students reported significantly more occurrences of LMVPAs out of school than during school. Significant interaction between grade and gender indicated that third grade boys reported more Total MVPAs and LMVPAs than third grade girls, but fourth grade boys reported fewer Total MVPAs and LMVPAs than fourth grade girls reported fewer Total MVPAs and LMVPAs than fourth grade girls. During the 3-day reporting period, 12.3% of boys and 13.3% of girls reported no LMVPAs, and 35.6% of boys and girls reported fewer than one LMVPAs per day. While the majority of children reported obtaining at least some activity daily, a substantial proportion of children in this sample reported fewer than one LMVPA daily, indicating that many children may not be obtaining adequate amounts of physical activity.

Children's frequency of consumption of foods high in fat and sodium.

We administered a food frequency instrument to third-fifth grade students (n = 943) in four Texas schools. Comparison of foods reported on the food frequency questionnaire and on 24-hour dietary recalls (n = 7) produced a percent agreement of 83.3. The most frequent 25 foods accounted for 64.0% of food choices across all meals, 93.5% of breakfast choices, 76.4% of lunch choices, 70.5% of supper choices, and 76.0% of snack choices. Breads, milk, hamburger or steak, soda pop, tomato sauce or tomatoes, and cheese were the most frequently consumed foods. Fruits and juices accounted for 6.1% of total selections for boys and 6.6% for girls, while vegetables accounted for 15.7% of total selections for boys and 16.2% for girls. Fruit was more likely to be consumed for snacks than for meals, and vegetables were consumed in about the same frequency at lunch and supper and for snacks. We analyzed the total fat, saturated fat, and sodium content of the most frequently consumed foods. Seventeen of the top 25 foods for the total day and 13-16 for each meal or snack exceeded by at least 50% the recommended levels for fat, saturated fat, or sodium. The pattern of consumption was one of frequent consumption of a relatively small number of foods, many of which are high in fat or sodium.

Validity of the observation of children's physical activity.

An observational method for quantifying intensity of activity was validated against min-by-min heart rates during physical education periods. The mean heart rate values increased as the activity points increased. Moderate average correlations were obtained between the min-by-min activity points and heart rates. A time series regression analysis accounted for 72% of the variance in heart rate values with a model combining heart rate in the previous min and activity points. Further work on estimates of average metabolic units for activity categories will enable future investigators to obtain more precise estimates of energy expenditure from this observation system.

School promotion of healthful diet and physical activity: impact on learning outcomes and self-reported behavior.

The Go For Health Program included classroom health education and environmental changes in school lunch and physical education to foster healthful diet and exercise among elementary school children. Interventions were based on social learning theory and implementation was based on an organizational change strategy for school innovations. Two schools were assigned to intervention and two to control conditions. Cognitive measures (behavioral capability, self-efficacy, behavioral expectations) and self-reported diet and exercise behavior were assessed at baseline and following intervention. Data were analyzed by ANOVA using the student and then the school as the unit of analysis. Statistically significant changes were observed for diet behavioral capability, self-efficacy, and behavioral expectations, use of salt, and exercise behavioral capability (fourth grade), self-efficacy (fourth grade) and frequency of participation in aerobic activity. The results provide evidence for program impact on learning outcomes and student behavior.

Implementing organizational changes to promote healthful diet and physical activity at school.

Diet and physical activity patterns appear to be learned at early ages, suggesting the need for school-based intervention. The potential of schools to improve children's diet and physical activity has been offset by countervailing school environments. In the first year of the "Go For Health" health promotion project, organizational change innovations were implemented to facilitate changes in school lunch, physical education, and classroom health education in support of healthful student diet and physical activity. At first follow-up after one year of intervention, the amount of sodium in selected foods served in school lunch was reduced from baseline (1985) to year one (1986) in the experimental schools by 29 and 33%, respectively, and fat was reduced by 28 and 42%, respectively. At first follow-up, students in the experimental schools participated in fitness activities 44.1 and 38.0% of the time, compared with 19.5 and 22.7% in the control schools.

School promotion of healthful diet and exercise behavior: an integration of organizational change and social learning theory interventions.

In the Go For Health project, interventions based on organizational change and social learning theory facilitate changes in diet and exercise behavior by elementary school children. Baseline data documented the need for behavior change. Based on chemical analyses, average per meal amounts of total fat and sodium were higher than national recommendations: total fat was 29.3% higher than U.S. Dietary Goals; sodium was 107.4% greater than recommended levels. Observations of students in physical education class revealed children moved through space 50.1% of the time and moved continuously an average of 2.2 minutes per class period. These findings suggest the need for policy and practice changes in the school environment to enable children to engage in more healthful diet and exercise behavior.