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Segmented School Physical Activity and Weight Status in Children: Application of Compositional Data Analysis
Ryan Donald Burns1, Timothy A Brusseau1, Yang Bai1
1Department of Health & Kinesiology, University of Utah, Salt Lake City, UT 84112, USA.
Summary
Promoting physical activity during school physical education and recess is linked to lower body mass index (BMI) z-scores in children. Reallocating steps from lunch to these activities showed significant weight-related benefits.
Area of Science:
- Pedometrics
- Child Health
- Epidemiology
Background:
- Childhood obesity is a significant public health concern.
- Understanding the impact of physical activity patterns during the school day is crucial for developing effective interventions.
- Previous research has often analyzed total daily physical activity, but segment-specific analysis within schools offers novel insights.
Purpose of the Study:
- To apply compositional data analysis (CoDA) to segmented school step counts.
- To associate step count composition during school hours with body mass index (BMI) z-scores in children.
- To determine the impact of reallocating steps between different school segments on BMI z-scores.
Main Methods:
- Utilized piezoelectric pedometers to collect step count data during physical education, recess, lunch, and academic classes in 855 fourth and fifth graders.
- Employed a multi-level mixed effects model to associate step count composition with BMI z-scores.
- Applied compositional isotemporal substitution to quantify changes in BMI z-scores resulting from step reallocation between school segments.
Main Results:
- A higher proportion of steps accumulated during physical education and recess, relative to other segments, was significantly associated with lower BMI z-scores.
- Reallocating 5% to 15% of steps from lunchtime to physical education or recess resulted in a decrease in BMI z-scores ranging from -0.07 to -0.25 standard deviation units.
- The findings highlight the relative importance of specific school activity periods for weight management.
Conclusions:
- School-based physical activity promotion strategies should prioritize physical education and recess for their impact on children's weight status.
- Targeting step reallocation from less active periods (e.g., lunch) to more active periods (physical education, recess) can contribute to reducing BMI z-scores.
- Compositional data analysis provides a valuable framework for understanding the nuanced relationship between physical activity patterns and health outcomes in children.
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