Promoting Physical Activity and a Healthful Diet among Children: Results of a School-Based Intervention Study

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Bruce G. Simons-Morton, EdD, MPH, Guy S. Parcel, PhD, Tom Baranowski, PhD, Ronald Forthofer, PhD, Nancy M. O'Hara, PhD

Introduction Childhood diet and physical activity may lead to increased risk for cardiovascular disease (CVD) in adulthood.! Promoting a healthful diet and regular vigorous physical activity among children is a national public health objective.2 School is an ideal setting in which to promote healthful diet and physical activity because these topics usually are part of the health education curriculum, and federally supported food services and statemandated physical education (PE) are widespread.3 School food services provide nutritious meals for 73.4c,, of all US public school students,4'5 but the high fat and sodium content is a concern.' An estimated 97% of first- through fourth-grade children in US public schools are enrolled in school PE programs for an average of 100 minutes per week.7 However, the frequency and duration of PE classes and the amount of moderate to vigorous physical activity (MVPA) children obtain during PE may be less than recommended.9 This study was designed to influence the school environment in terms of affect on student diet and physical activity at school. The Go For Health (GFH) program included a behaviorally-based health education curriculum, fitness-oriented PE, and lower fat and sodium school lunches. We report the effects of the program on children's dietary intake and physical activity during school.

Methods Design and Study Population The Texas City Independent School District (TCISD) was selected for the study because it is conveniently close to the university, it has an ethnic mix of stu-

dents, and it has curriculum, school lunch, and PE components. The district participated in the US Department of Agriculture school lunch program, and each school had its own on-premises kitchen, cafeteria, and food preparation staff. Third and fourth graders had PE daily, taught by PE specialists. Facilities at each school include a modem gymnasium and large outdoor playground area. The population of students was 62.3% Anglo-American, 20.9% Mexican-American, and 14.8% Afro-American. The ethnic distributions were comparable for both treatment and control conditions. Two of the four elementary schools (kindergarten through fourth grade) were assigned to intervention and two to control conditions. Third and fourth graders were assessed annually during three spring data collection periods.

Intervention Tlhe three GFH intervention components, based on social cognitive theory,"11 were the Go For Health Curriculum, Children's Active Physical Education (CAPE), and the New School Lunch (NSL). I Following the model of Charter Bruce G. Simons-Morton, Guy S. Parcel, Ronald Forthofer, and Nancy M. O'Hara are with the School of Public Health of the University of Texas Health Science Center, Houston, TX. Tom Baranowski is with the Georgia Prevention Institute, Medical College of Georgia, Augusta, Ga. Requests for reprints should be sent to Bruce G. Simons-Morton, EdD, MPH, Center for Health Promotion Research and Development, School of Public Health, University of Texas Health Science Center, PO Box 20186, Houston, TX 77225. This paper was submitted to the journal September 13, 1990, and accepted with revisions April 23, 1991.

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and Jones,12 we employed a four-step approach to program implementation and institutionalization.13 To foster quality implementation, the GFH staff provided ample training, consultation, and technical support to both teachers and food service staff. The purposes of the classroom health education, which consisted of six, behaviorally based modules, were to teach

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knowledge and skills essential to lifelong performance of the target diet and physical activity behaviors and foster the trans-

CAPE, which consisted of five, 6- to 8-week units, was designed to encourage enjoyable MVPA among children during

fer of learning about these behaviors from school to out-of-school environments.'0 The NSLwas designedtoprovide lower-fat, lower-sodiumluncheswithin the context of the existing school lunch program. Food purchasing, menus, recipes, and food preparation practices were modified.

PE classes. Each unit included two or three main cardiovascular fitness activities, such as dancing, running, aerobic games, jump rope, and obstacle courses. Each class session consisted of warmup, fitness development, cool down, and skill development or game activities.

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Total Fat (% Kcal)

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FIGURE 1-Means and 95% Confidence Intervals for Total Fat and Saturated Fat as a Percent of Calories In School Lunches (N = 12 meals per school) In Control and Intervention Schools at Baseline (Pre), after 1 Year (Mid), and after 2 Years (Post).

Measures and Procedures Program effects were assessed by analyzing the nutrient contents of lunches, conducting 24-hour dietary recalls, and observing students' physical activity during PE. NutienAnalysis of School Lunches. The identical menu was repeated in March and April each year of the study. At baseline, 12 meals were selected randomly from the March and April menus and analyzed for nutrient content. Recipe analyses, based on detailed interviews with each cook in the intervention schools at baseline and in all four schools at midtest and posttest, were conducted by trained staff nutritionists and analyzed by the Nutrition Coding Center

(NCC).4 Diet Recall. The 24-hour dietary recall interview was administered at posttest to random, cross-sectional subsamples of children, stratified by study school. Interviewers were trained according to NCC procedures and followed the NCC protocol for diet interviews. Each child was interviewed at home in the company of one parent, who was asked about ingredients, food preparation, and other items as needed.

988 American Journal of Public Health

Physical Activity. The time (in minutes) of MVPA performed by children during physical education was assessed by trained observers using the Children's Physical Activity Observation Form (CPAOF).'5 Study schools were observed on randomly selected days over a 2-month period each spring; all third- and fourthgrade classes were observed. Observers recorded on a minute-by-minute basis the type (e.g., basketball, jump rope) and intensity of physical activity. The CPAOF intensity categories have been validated against heart rate,15 and the average heart rate for MVPA was 172.2 (SD = 21.2) beats per minute. Interobserver agreement was 97.0% (n = 57 paired observations).

Analysis For energy and selected nutrients of potential concern in this age group, we calculated the means and 95% confidence intervals (CIs) of the repeated samples of school lunches in each school. For each separate treatment condition, we calculated the mean nutrient intakes from the 24-hour dietary interviews for selected nutrients and examined the contribution of school and bag lunches to total daily nutrient intakes. For each school at each reporting period, we calculated the MVPA means, standard deviations, medians, and 95% CIs for the medians."6 The median is the most appropriate statistic for purposes of comparing treatment effects because increases in the amount of MVPA on the part of only a few students could affect the mean value, obscuring true program effects. Percent of class time is preferable to minutes as an outcome because the scheduled length of PE classes varied somewhat from year to year, and the effective class time available for PE teachers and students, although similar in each school for a given year, varied somewhat from school to school due to local scheduling. The annual surveys are presented separately for each grade because most of one year's third graders became the next year's fourth graders; hence the data for each grade are not independent across years.

Results Diet

Recipe Analysis. Table 1 includes the means and the 95% CIs for total energy (in kilocalories [1 kcal = 4.2 kJ ]) and six nutrients in the 12 meals served in

each study school each year. Baseline values for the control schools, which were not collected directly, were estimated by averaging the values of the two intervention schools. Declines from baseline to posttest in each school for protein, carbohydrates, total fat, cholesterol, and calcium are the product of declines in energy. The decline in calories served in the intervention schools appears to have been due mainly to a reduction in the amount of fat and carbohydrates. Despite the declines in energy, vitamin A and calcium did not decline, and posttest values for all schools exceeded the USDA school lunch requirements for each nutrient. For example, at every reporting the average intake of energy in each school exceeded 33% of the total daily requirement for energy, which is 600 to 700 kcal per meal.'7 Shown in Figure 1 for each school is the average total fat and saturated fat as a percent of kcal served in the sample of 12 lunches. For both intervention schools the upper CIs of the posttest means were less than the pretest means, and in school 3 the upper and lower Cl values did not overlap. The mean percent fat declined in school 3 by 15.5%, from 41.3% to 35.6% of calories, and in school 4 by 10.3%, from 39.7% to 35.6% of calories. Average percent saturated fat declined in school 3 by 31.7%, from 16.1% to 11.0% of calories, and in school 4 by 18.8%, from 13.8% to 11.0% of calories. The means for percent total fat and saturated fat at posttest in the control school were within the imputed pretest 95% CIs. Figure 2 shows that the sodium content in the school food declined from baseline to posttest in school 3 by 53.6% from 2141.1 mg to 993.0 mg, and in school 4 by 40.2%, from 1730.0 mg to 1034.5 mg. These differences remained after controlling for kcals served. Sodium in the control schools did not decline from the imputed baseline value. Dietary RecaUl. Table 2 shows the analysis of the posttest 24-hour recalls for the nutrients of interest. Students in the intervention group, compared with students in the control group, reported fewer calories (2094 vs 2135 [1 calorie = 4.2 J]) and less total fat (77 g vs 90 g), saturated fat (29 g vs 34 g), and sodium (2873 mg vs 3378 mg) for the total day. In comparison with control group students, intervention group students reported consuming less total fat, saturated fat, and sodium in both tray and bag lunches.

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Children's Diet and Physical Activity

PhysicalActivity Table 3 shows medians, means, and standard deviations for minutes of MVPA for observed students in grades three and four at each study school at baseline, midtest, and posttest. At baseline, mean MVPA for third and fourth graders was less than 3 minutes at each school; medians were 2.0 minutes or lower. At posttest, mean minutes had increased in school 3 to 11.7 (third grade) and 15.0 (fourth grade) and in school 4 to 16.2 (third grade) and 16.1 (fourth grade) per class. Median minutes as a percent of class time and 95% CIs around the medians are shown for third and fourth grade in Figure 3. For both grades, the median percent of class time in MVPA at baseline was zero in three schools and less than 10% in school 3. At posttest, the control school medians were still no greater than 5% of class time. In the intervention schools, however, the posttest medians were substantially higher, 28% of class time for third graders in school 3, and 39% of class time or greater for the other intervention groups. Except for fourth grade in school 3, the upper and lower 95% CI values do not overlap with the baseline means.

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FIGURE 2-Means and 95% Confidence Intervals for Sodium In School Lunches (N = 12 Meals perSchool) In Contol andc Intervention Schools at Baseline (Pre), after 1 Year (Mid), and after 2 Years (Post).

Discussion The results show strong positive program effects on children's diet and physical activity at school. At posttest, school lunches in the intervention schools provided less energy, fat, and sodium compared with baseline and with the control schools, while adequate levels ofother essential nutrients were maintained. Similarly, children's physical activity in the intervention schools was much higher at posttest than at baseline and in comparison with the control schools. Several studies have demonstrated that sodium reductions can be accomplished by intervention directed at school meals.18'19 However, no studies have reported systematic reductions in fat and sodium in school lunches. In the GFH intervention schools, sodium content was reduced to target levels, saturated fat reductions of 31.7% and 18.8% occurred, and posttest values approached the target goal of 10% of kcals served. Total fat reductions were modest, 15.5% and 10.3%, and the target goal of 30% of kcals was not reached, indicating that it is easier, even in institutional settings, to substitute fat type than to reduce the amount of fat. The 24-hour dietary recall data indicate that the changes in nutrients served in

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American Journal of Public Health 989

Sim2ons-Morton et at.

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Physical Actvity (MVPA) In Control and Intervention Schools at Baseline (Pre), after 1 Year (Mid), and after 2 Years (Post); Third and Fourth Grade.

school lunch contributed to improvements in total daily dietary intake of calories, total fat, saturated fat, and sodium. Children did not make up in other meals for reductions of fat and sodium in school lunches. Energy, calcium, and vitamin A remained adequate at posttest in all schools, suggesting that reductions in fat

990 American Journal of Public Health

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can be accomplished without undue reductions in other essential nutrients. Several studies have demonstrated that it is possible to modify PE to improve cardiorespiratory fitness.'' Our results indicate that it is possible to increase time devoted to MVPA from less than 10% to more than 40% of available class time. At posttest, the typical student in the intervention schools obtained about 16 minutes of MVPA per daily PE period, or 80 minutes of MVPA per week. It must be noted that these modest results were obtained after 2 years of intervention that involved one staff person virtually full time in the provision of intensive training of PE teachers. Because PE accounts for nearly half of children's total daily physical activity,23 the extremely low level of MVPA observed in all schools at baseline is a cause for concern, particularly if future research determines that low levels of activity during PE are prevalent in American schools. This is the first US study to demonstrate the potential of altering the school environment to promote a more healthful diet and more vigorous physical activity among children, although at least one successful European study has been reported.' Strengths of the present study include planned implementation of theorybased individual and organizational interventions, two intervention and two control schools within the same district, and objective measures of diet and physical activity. Limitations of the study include the lack of baseline recipe data for the control schools, nonrandom assign-

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ment of schools to treatment conditions, and the small number of study schools. The results of this efficacy study suggest that school is a potentially important site for improving children's diet and physical activity and that such changes are possible. In our experience, however, schools do not change readily, and substantial staff training should accompany policy changes regarding healthful school lunch and vigorous physical education. Before widespread implementation of these changes occurs, effectiveness studies with larger numbers of schools are needed to determine the ability to generalize these approaches and to assess cost effectiveness. El

Acknowledgments This research was funded by NHLBI Grant 33376. We gratefully acknowledge the administrators, teachers, and staff of the Texas City Independent School District for their support and cooperation. Also, we thank Renee Fleishman for data preparation and Iris Huang for statistical analyses. This research was presented at the annual meeting of the American Public Health Association held in New York City September 30 to October 4, 1990.

References 1. Hetzel BS, Berenson GS. Cardiovascular Risk Factors in Chldhood Epidemiology and Prevention. New York: Elsevier Science Publishers; 1987. 2. Public Health Service. Promoting Health! Preventing Disease: Year 2000 Objectives for the NatiorL Washington, DC: US Dept of Health and Human Services; 1991. DHHS Publication II (PHS) 91-50213. 3. Pigg RM Jr. The contribution of school

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Children's Diet and Physical Activity

health programs to the broader goals of public health: the American experience. J Sch Health. 1989;59:25-30. 4. RadzikowskiJ, Gale SKI Requirements for the national evaluation of school nutrition programs. Am J Clin Nutr. 1984; 40(suppl):365-367. 5. Hanes S, Vermeersch J, Gale S. The national evaluation of school nutrition programs: program impact on dietary intake. Am J Clin Nutr. 1984;40(suppl):390-413. 6. Frank G. Primary prevention in the school arena: a dietary approach. Health Values. 1983;7:14-21. 7. Ross JG, Pate RR, Corbin CB, Delpy LA, Gold RS. The National Children and Youth Fitness Study II: What is going on in the elementary physical education program? J Phys Ed Rec Dance. 1987;58:78-84. 8. National Association for Sport and Physical Education. NASPE 1988: a year in review. NASPE News. 1989;24:1. 9. Simons-Morton BG, Parcel GS, O'Hara NM, Blair SN, Pate RR. Health related physical fitness in childhood: status and recommendations. Annu Rev Public Health. 1988;9:403-425. 10. Parcel GS, Simons-Morton BG, O'Hara NM, Baranowski T, Wilson B. School promotion of healthful diet and physical activity: impact on learning outcomes and self-

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reported behavior. Health Educ Q. 1989;16:181-199. BanduraA. SocialFoundations ofThought and Action. Englewood Cliffs, NJ: Prentice-Hall, Inc; 1986. Charter WW, Jones JE. On the risk of appraising non-events in program evaluation. EducRes. 1973;2:5-7. Parcel GS, Simons-Morton BG, Kolbe LU. School health promotion: integrating organizational change and student learning strategies. Health Educ Q. 1988;15:435450. Dennis B, Ernst N, Hjortland N, Tillotson J, Grambsch VB. The NHLBI nutrition data system. J Am Diet Assoc. 1980;77: 641-645. O'Hara N, Baranowski T, Simons-Morton BG, Wilson B, Parcel GS. Validity of the observation of children's physical activity. Res Q Exrcise Sport. 1989;60:42-47. Walsh JE. Nonparametric confidence intervals and tolerance regions. In: Sarhan AE, Greenberg BG, eds. Conttibutions to Order Statistics. New York: John Wiley; 1962:136-143. National Academy of Sciences: Recommended Dietary Allowances, 10th ed. Washington, DC: National Academy of Sciences; 1989.

18. Frank G, White M. Application of a sodium-modified recipe program in school lunch. SchFoodServResRev. 1983;7:2-4. 19. Ellison RC, Capper AL, Goldberg RG, Witshi JDC, Stare FJ. The environmental component: changing school food service to promote cardiovascular health. Health Educ Q. 1989;16:285-297. 20. Dwyer T, Coohan W, Leitch 0, et al. An investigation of the effect of daily physical activity on the health of primary school students in South Australia. Int J EpidemioL 1983;12:308-313. 21. Duncan B, Boyce T, Itami R, Paffenbarger N. A controlled trial of physical fitness programs for fifth grade students. J Sch Health. 1983;53:467-471. 22. Coates TJ, Jeffery RW, Slinkard LA. Heart healthy eating and exercise: introducing and maintaining changes in health behaviors. Am JPublic Health. 1981;71:15-23. 23. Simons-Morton, BG, O'Hara NM, Simons-Morton DG, Parcel GS. Children and fitness: a public health perspective. Res Q Exercise Sport. 1987;58:295-303. 24. Grafner L, Heinrich J, Knappe J, Holtz H. Atherosclerosis precursors in school children-results of a two-year intervention study. Cor Vasa 1987;29:421-427.

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