The number of purposeful headers female youth soccer players experience during games depends on player age but not player position
Bibliographic record
Abstract
Purpose: The aim of this study was to describe the frequency and characteristics of purposeful soccer heading in youth players based on age, position, and head impact location.Methods: Game video was recorded for three female youth teams [under-13 (U13), under-14 (U14), and under-15 (U15)] for an entire season. Purposeful headers were categorized for these three teams and their opposition.Results: The median number of headers experienced during games was one, and the minimum number of headers was zero. The maximum number of headers performed during a game by a U13 player was eight, and nine for U14 and U15 players. There were statistically significant differences in the number of headers performed in the different age groups (p < 0.05), but no significant differences between player position (p > 0.05). There was no significant association between head impact location and game scenario (p > 0.05).Conclusions: Our study shows that youth players frequently head the ball during games. This information may guide data-driven approaches regarding heading restrictions in youth soccer.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".