Temporal trends in the cardiorespiratory fitness of children and adolescents representing 19 high-income and upper middle-income countries between 1981 and 2014
Bibliographic record
Abstract
OBJECTIVE: To estimate international and national temporal trends in the cardiorespiratory fitness (CRF) of children and adolescents and to examine relationships between temporal trends in CRF and temporal trends in broad socioeconomic and health-related indicators across countries. METHODS: Data were obtained from a systematic search of studies that explicitly reported 20 m shuttle run test (a validated measure of CRF) descriptive data on apparently healthy individuals aged 9-17 years. Following the estimation of relative peak oxygen uptake (mL/kg/min) as a measure of CRF, sample-weighted temporal trends were estimated at the country-sex-age level using best-fitting linear or polynomial regression models relating the year of testing to mean CRF. Poststratified population-weighted mean changes in absolute and per cent CRF were estimated. Pearson's correlations were used to describe the association between linear temporal trends in CRF and linear temporal trends in broad socioeconomic and health-related indicators. RESULTS: Temporal trends were estimated from 965 264 children and adolescents from 19 high-income and upper middle-income countries between 1981 and 2014, using data from 137 studies. Collectively, there was a moderate decline in CRF of 3.3 mL/kg/min (95% CI -3.5 to -3.1), equivalent to a decline of 7.3% (95% CI -7.8% to -6.7%) over the 33-year time period. This international decline diminished with each decade and stabilised near zero around 2000. The decline was larger for boys than girls and was similar for children and adolescents. Trends also differed in magnitude and direction between countries, with most showing declines. There was a strong negative association between country-specific trends in income inequality (Gini index) and trends in CRF across 18 countries; meaning, countries approaching income equality had more favourable trends in CRF. CONCLUSIONS: There has been a substantial decline in CRF since 1981, which is suggestive of a meaningful decline in population health. However, the international trend in CRF has not followed the anticipated trajectory, diminishing and stabilising with negligible change since 2000. CRF data are needed from children in low-income and middle-income countries to more confidently determine true international trends and determine whether temporal trends are similar to those observed in high-income and upper middle-income countries.
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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 | 0.003 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.003 | 0.005 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".