Comparison of Changes in Body Mass Index and Cardiopulmonary Fitness Between Normal Weight vs. Overweight and Obese Fourth Grade Students After a School-Based Physical Activity Program: A Non-Randomized Intervention Study Open Access

Moon, Rena C (Summer 2018)

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Background: Approximately one in five children aged 6-11 are obese nationwide. Although obesity is associated with many negative health consequences, improving cardiopulmonary fitness can create a better health outcome. In order to improve cardiopulmonary fitness among children, many school-based physical activity (PA) programs have been implemented. Nevertheless, the outcomes of school-based PA interventions are often not stratified by baseline weight status, and how the intervention improves the health of overweight and obese children is not well established.

Aims: To evaluate whether overweight/obese children had similar changes in body mass index (BMI) and cardiopulmonary fitness as with normal weight children after a school-based PA intervention (Health Empowers You!), controlling for sex, race/ethnicity, and socioeconomic status

Methods: Using convenience sampling method at the school-level, 21 intervention and 7 control schools in Atlanta, GA were included in the study during 2015-2016 academic year. At the student-level, sample sizes were 2,341 for BMI analysis, and 1,799 for Progressive Cardiovascular Endurance Run (PACER) test analysis. Two sample t-tests and two-way ANOVA of the mean differences between pre- and post-intervention for BMI and PACER were conducted, stratified by pre-intervention weight status.  Multiple linear regression models were fit for each subject.

Results: Normal weight, overweight, and obese students did not show changes in BMI after the intervention. However, being overweight or obese was significantly associated with the decrease in raw BMI, holding intervention status fixed (p<0.01 and p<0.01, respectively). Normal weight students showed a significant improvement in PACER test (p<0.01), while overweight and obese students did not show changes in PACER test after the intervention (p=0.94 and p=0.25, respectively). In other words, normal weight students had a better improvement in PACER test than overweight or obese students with the intervention.

In the control group, changes in PACER test were not different for overweight and obese vs. normal weight group (p=0.86 and 0.68, respectively). In the intervention group, overweight and obese students showed significantly less improvement in PACER test (by 1.61 laps and 2.12 laps, respectively) than normal weight students (p=0.03 and p=0.02, respectively).      

Conclusion: This analysis contributes to the literature on how overweight and obese children are affected differently by school-based PA intervention from normal weight children. Different approaches for overweight and obese children may be needed to achieve improvements in cardiopulmonary fitness.

Table of Contents

I...... Introduction. 1


A.   Importance of Being Metabolically Healthy. 1


B.   Benefits of Cardiopulmonary Fitness and Physical Activity. 1


C.   School-Based Efforts to Increase Physical Activity in Children. 2


D.   Necessity of Additional Analysis for School-Based Physical Activity Programs 3


E.   Gaps in the Literature. 4


II..... Goals and Objectives 6


III.... Methods 7


A.   Study Design and Population. 7


B.   Description of Health Empowers You! Intervention. 8


C.   Data Sources 9




2. Department of Education. 11


D.   Data Measures 11


1.  Exposure Variables 11


2. Outcome Variables 12


3.  Covariates 12


E.   Data Analysis 13


Missing Data. 14


IV.... Results 15


A.   Descriptive Statistics 15


B.   Changes in Raw BMI 15


C.   Changes in PACER test 16


D.   Multiple Regression Model 17


E.   Sensitivity Analyses 20


V..... Discussion. 21


Strengths and Limitations 23


VI.... Future Directions 26


Implications 26


VII... Tables 28


VIII.. Figures 32


IX.... References 33


X..... Appendices 38

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