83 Heart rate recovery changes following repetitive head impacts in Canadian football athletes
Bibliographic record
Abstract
Purpose Subconcussive head impacts during contact sports are challenging to identify and their consequences remain elusive. Impaired autonomic nervous system responses involving altered cardiac dynamics have been reported following mild traumatic brain injury but remain underexplored in contact sports. This study monitored online effects of head impact exposure on athletes’ cardiovascular function during a Varsity Canadian football season.Methods Heart rate recovery (HRR) segments (n=225) were extracted from 11 skill players (median [IQR] age: 23 [2] years; body mass index: 26 [1] kg/m²) equipped with two wearable sensors recording accelerations, heart rate, velocity, estimated metabolic energy expenditure, and fast head acceleration events (HAE). The heart signal derivative was used to detect HRR segments which were then matched with the number and intensity of HAE previously sustained during the game.Results Following a single HAE above 40 g, the median HRR (ΔHR/Δt=0.461 bpm/s, n=23 segments) decreased of 19% (p=0.005) compared to segments prior to the event (ΔHR/Δt=0.569 bpm/s, n=182 segments). This reduction was also observed with HAE as low as 20 g (0.474 bpm/s, n=42 segments; 30% reduction; p= 4.30e-08, figure 1). These were neither correlated with metabolic energy expenditure (R²=0.009, p=0.541) nor with peak running velocity reached before HAE (R²=4e-04, p=0.896).Abstract 83 Figure 1Heart rate recovery rates for segments binned by upper bounds for peak linear acceleration of 10 g (i.e., no head acceleration event – HAE –, leftmost), up to 20 g (second box), up to 30 g (third box), up to 40 g (fourth box) and 40 g and up (last box on the right). Significance test: Kruskal-Wallis rank sum test relative to the «no impacts» sample, thresholds: * = 0.05, ** = 0.01, *** = 0.001Conclusion This demonstrates a possible direct relationship between HAE starting at 20 g and disturbed cardiac response. Given the repetitive nature of subconcussive hits beyond this ≥ 20 g threshold, there is an urgent need to investigate whether or how altered heart rate kinetics could influence severity of head injury in contact sports.
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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 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".