500 BO04 – Down three: video-suspected injuries in youth tackle football following a reduction in number of players on-field
Bibliographic record
Abstract
Musculoskeletal (MSK) injuries and concussions (SRC) are of concern in tackle football, and youth are understudied compared to elite athletes. Policy change is of interest as a means to improve player safety. A reduction in number of players on-field may reduce the number of collisions and subsequently injuries within this population, potentially aiding in future injury prevention strategies. To compare video-suspected (VS) concussion and non-concussion injury rates in a modified 9-on-9 13–15 years old Canadian football season to a traditional 12-on-12 season using video-analysis. Prospective cohort Youth tackle football (Calgary, Canada). Football players aged 13–15 years included 384 players (n=18 teams) participating in 2020 and 500 players (n=12 teams) in 2022. Video data were anonymized. In 2020, in accordance with provincial COVID-19 cohort restrictions, there was a reduction in the number of on-field players (9-on-9) and field-dimensions (150x50 yards). The 2021 season returned to 12-on-12 with field dimensions of 150x65 yards. Independent variables included cohort (9-on-9, 12-on-12) and team unit (offense, defense, kicking team, receiving team). Twenty regular season games (10 in each season) were analyzed. Using previously validated criteria, VS-concussion and non-concussion injuries were identified via Dartfish video software. Using negative binomial regression, VS injury rates (/100 player-plays and/10 gameplay-minutes) and incidence rate ratios (IRR) with 95% confidence intervals were estimated to examine differences between years. In total, 10 VS-concussions and 40 VS non-concussion injuries were identified. No significant differences were identified between 2020 and 2021 seasons for VS concussions [IRRPlays (offense): 0.38; 95% CI: 0.08, 1.85] nor non-concussions [IRRPlays (offense): 0.61; 95% CI: 0.27, 1.38]. No injury or concussion rate differences were identified with a reduced number of players on a smaller field. Future research may benefit from combining video-analysis with injury surveillance and accelerometry data to improve prevention efforts.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".