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Neurovascular coupling response is maintained despite exposure to repetitive sub-concussive head trauma over the course of one contact-sport season
  1. Jonathan D Smirl1,
  2. Alexander D Wright1,2,3,4,
  3. Kevin Bouilane1,
  4. Kelsey Bryk1,
  5. Michael Jakovac3,
  6. Paul van Donkelaar4
  1. 1School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, Canada
  2. 2MD/PhD Program, University of British Columbia, Vancouver, Canada
  3. 3Southern Medical Program, University of British Columbia Okanagan, Kelowna, Canada
  4. 4Department of Experimental Medicine, University of British Columbia, Vancouver, Canada

Abstract

Objective To examine how head-impact exposures affect the elevation in cerebral blood velocity (CBV) in the posterior cerebral artery (PCA) during visual tasks.

Design Prospective Cohort.

Setting Laboratory.

Participants To date: 40 male contact-sport athletes (19.4±1.2 years) and 3 cross-country athletes (20.0±1.0 years) have completed testing (non-contact controls).

Intervention Transcranial Doppler ultrasound indexed PCA CBV during visual tasks. Participants closed their eyes (20-seconds), and when prompted, opened them and completed a visual task (40-seconds). Testing occurred prior-to and upon-completion-of the competitive athletic season. Raw traces from each trial were averaged to enhance the signal-to-noise ratio of outcome measurements. Independent variable tested was time (2).

Outcome Eyes-closed CBV (cm/s), peak elevation in CBV (cm/s), relative change in CBV (%) and total activation during the first 30 seconds of the task (indexed via area under the curve-AUC). Head-impact exposure was characterised in a subset of contact-sport athletes (n=29) using the xPatch (X2 Biosystems).

Main results RM-ANOVA indicated the contact-sport season had no effects on any outcome metrics: Eyes-closed CBV (p=0.181), peak CBV (p=0.117),% CBV elevation (p=0.252) and AUC (p=0.366), despite experiencing cumulative peak linear accelerations of 8147.2±6215.5 g, and cumulative peak rotational accelerations of 34.5×106 ± 59.0×106 rad/?s2.

Conclusions The results from this study suggest neurovascular coupling metrics are maintained throughout a contact-sport season. This indicates nutrient delivery is maintained for neurocognitive challenges despite possible impairments in cerebrovasculature’s ability to buffer blood pressure challenges associated elevations in rotational accelerations experienced during a contact-sport season.

Competing interests None.

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