The relationship between physical activity and body composition changes over time in children
Bibliographic record
Abstract
Physical inactivity is a risk factor for chronic disease and obesity. The objective of this three year longitudinal study was to determine how body composition and physical activity (PA) change over time. Body fat (Slaughter equation) and body mass index (BMI) were determined for children (8 to10 years) over one year (n=41) and 2 years (n=15). Triaxial accelerometry assessed daily PA (kcal/kg/d). Physical activity increased by 1.78 ±0.68 kcal/kg/d (P=0.007) over one year, while PA increased by 2.69±1.07 kcal/kg/d over two years (P=0.025). There was no change in body fat over one year (P=0.204) or two years (P=0.425). When controlling for initial body fat and sex, there was a relationship between changes in body fat and final PA (r 2 =0.302, P=0.017). Height (P<0.0001) and mass (P<0.012) significantly increased over the one and two year periods. While BMI increased over one year (P=0.001) but not over two years (P=0.416). Body mass index did not significantly change over time after adjusting for changes expected due to growth. When controlling for initial BMI and sex, there was no relationship between changes in BMI and final PA (r 2 =0.157, P=0.726). Thus, changes in body fat, but not BMI are predicted by the final level of PA achieved by children. Supported by Manitoba Institute of Child Health.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".