Contact events in rugby union and the link to reduced cognition: evidence for impaired redox‐regulation of cerebrovascular function
Bibliographic record
Abstract
New Findings What is the central question of this study? How does recurrent contact incurred across a season of professional rugby union impact molecular, cerebrovascular and cognitive function? What is the main findings and its importance? A single season of professional rugby union increases systemic oxidative–nitrosative stress (OXNOS) confirmed by a free radical‐mediated suppression in nitric oxide bioavailability. Forwards encountered a higher frequency of contact events compared to backs, exhibiting elevated OXNOS and lower cerebrovascular function and cognition. Collectively, these findings provide mechanistic insight into the possible cause of reduced cognition in rugby union subsequent to impairment in the redox regulation of cerebrovascular function. Abstract Contact events in rugby union remain a public health concern. We determined the molecular, cerebrovascular and cognitive consequences of contact events during a season of professional rugby. Twenty‐one male players aged 25 (mean) ± 4 (SD) years were recruited from a professional rugby team comprising forwards ( n = 13) and backs ( n = 8). Data were collected across the season. Pre‐ and post‐season, venous blood was assayed for the ascorbate free radical (A •– , electron paramagnetic resonance spectroscopy) and nitric oxide (NO, reductive ozone‐based chemiluminescence) to quantify oxidative–nitrosative stress (OXNOS). Middle cerebral artery velocity (MCAv, Doppler ultrasound) was measured to assess cerebrovascular reactivity (CVR), and cognition was assessed using the Montreal Cognitive Assessment (MoCA). Notational analysis determined contact events over the season. Forwards incurred more collisions (Mean difference [ M D ] 7.49; 95% CI, 2.58–12.40; P = 0.005), tackles ( M D 3.49; 95% CI, 0.42–6.56; P = 0.028) and jackals ( M D 2.21; 95% CI, 0.18–4.24; P = 0.034). Forwards suffered five concussions while backs suffered one concussion. An increase in systemic OXNOS, confirmed by elevated A •– ( F 2,19 = 10.589, P = 0.004) and corresponding suppression of NO bioavailability ( F 2,19 = 11.492, P = 0.003) was apparent in forwards and backs across the season. This was accompanied by a reduction in cerebral oxygen delivery ( , F 2,19 = 9.440, P = 0.006) and cognition ( F 2,19 = 4.813, P = 0.041). Forwards exhibited a greater decline in the cerebrovascular reactivity range to changes in PET CO2 ( compared to backs ( M D 1.378; 95% CI, 0.74–2.02; P < 0.001).
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| 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".