Examining the Regulation of Cerebral Blood Velocity and Postural Control Following Acute Exposure to Heading in Women Footballers

Abstract

Background: Repeated heading has been associated with an increased risk of neurodegenerative disease and has been shown to acutely alter cerebrovascular outcomes and postural control. The majority of work investigating heading and these outcomes have utilised heading stimuli which lack ecological validity and recruited almost exclusively males despite suggestions women may suffer greater cerebral white matter alterations following head impacts. This study assessed whether a more ecologically valid heading stimulus alters indices of cerebral blood velocity regulation and postural control in women. Methods: On separate days, nineteen female footballers completed a heading and time-matched non-heading control trial wherein participants remained seated. The heading trial consisted of six headers performed in one hour (one every 10 minutes), with a ball travelling at 40 ± 5 km/h. Cerebrovascular reactivity to hypercapnia and hypocapnia were determined using five repetitions of breath holding and hyperventilation respectively. Dynamic cerebral autoregulation was assessed via analysing the relationship between middle cerebral artery blood velocity and mean arterial pressure during 5 minutes of repeated squat stands performed at 0.05 Hz. Postural control was analysed by the concurrent assessment of objective balance and centre of pressure displacement during double-leg stance. Outcomes were assessed before and one hour after the heading and control trial. Results: No significant time by trial interaction was present for the hypercapnic (P=0.48, ηp2=0.05) or hypocapnic (P=0.47, ηp2=0.06) challenge. Similarly, no interaction effect was present for any metric of dCA (P>0.12, ηp2 <0.16) or postural control (P>0.13 ηp2 <0.01). Conclusion: The cerebral blood velocity response to changes in carbon dioxide and blood pressure, and maintenance of postural control were not changed following a realistic heading stimulus in female footballers. Future study should assess these indices following prolonged exposure.