Changes in Canadian Adolescent Time Use and Movement Guidelines During the Early COVID-19 Outbreak: A Longitudinal Prospective Natural Experiment Design
Bibliographic record
Abstract
BACKGROUND: Comprehensive, prospective, longitudinal data are lacking on the effects of the COVID-19 outbreak on adolescents' movement behaviors (moderate to vigorous physical activity [MVPA], sleep, recreational screen use, and strengthening exercises). The purpose was to compare movement behavior changes among adolescents affected by the pandemic with controls. METHODS: Survey data from 10,659 students at 82 Canadian secondary schools (aged 12-19 y) during the 2018-2019 and 2019-2020 school years were analyzed. One-year change in time spent in movement behaviors and likelihood of meeting Canadian 24-hour movement guidelines was compared between preoutbreak controls (October 2019-March 2020) and early outbreak respondents (May-July 2020) after controlling for sociodemographic factors. RESULTS: Compared with controls, the early outbreak group reported a greater decrease in time spent in MVPA and greater increases in time spent in sleep and recreational screen use. The early outbreak group was less likely to meet MVPA and recreational screen time guidelines but more likely to meet guidelines for strengthening exercises and sleep duration. CONCLUSIONS: Findings for MVPA and screen time changes were in the same direction as retrospective reports from children and youth samples. Sleep adherence may have improved due to no longer having to commute to school. Strengthening exercises may represent physical activity that is easier to do in the home with minimal equipment leading to improved adherence during restrictions.
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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 | 0.008 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".