Cerebral blood flow regulation is not acutely altered after a typical number of headers in women footballers

Abstract

BackgroundThe repeated act of heading has been implicated in the link between football participation and risk of neurodegenerative disease, and acutely alters cerebrovascular outcomes in men. This study assessed whether exposure to a realistic number of headers acutely influences indices of cerebral blood flow regulation in female footballers.MethodsNineteen female players completed a heading trial and seated control trial on two separate days. The heading trial involved six headers in 1 h (one every 10 min), with the ball traveling at 40 ± 5 km/h. Cerebrovascular reactivity to hypercapnia and hypocapnia was determined using serial breath holding and hyperventilation attempts. Dynamic cerebral autoregulation (dCA) was assessed by scrutinizing the relationship between cerebral blood flow and mean arterial blood pressure during 5 min of squat stand maneuvers at 0.05 Hz. Neurovascular coupling (NVC) was quantified as the posterior cerebral artery blood velocity response to a visual search task. These outcomes were assessed before and 1 h after the heading or control trial.ResultsNo significant time by trial interaction was present for the hypercapnic (P = 0.48, ηp2 = 0.05) and hypocapnic (P = 0.47, ηp2 = 0.06) challenge. Similarly, no significant interaction effect was present for any metric of dCA (P > 0.12, ηp2 < 0.16 for all) or NVC (P > 0.14, ηp2 < 0.15 for all).ConclusionThe cerebral blood flow response to changes in carbon dioxide, blood pressure and a visual search task were not altered following six headers in female footballers. Further study is needed to observe whether changes are apparent after more prolonged exposure.

The acute influence of amateur boxing on dynamic cerebral autoregulation and cerebrovascular reactivity to carbon dioxide

“…Typically this is accepted when P ET CO 2 is within ~ 8 mmHg of eucapnia (Coverdale et al 2014 ; Verbree et al 2014 ). As is typical during SSM (Smirl et al 2015 , 2022 ; Burma et al 2020a ; Jack et al 2022 ), this was achieved during our dCA assessment, but was exceeded during the hyperventilation protocol. However, our hyperventilation challenge replicated a protocol known to be sensitive to change in the days following a concussive event (Len et al 2011 ), and we observed similar decreases in P ET CO 2 .…”

“…A decrease in phase has been observed during SSM following a season of contact sports, and the magnitude of this change was also positively associated with the accumulation of head impact accelerations (Wright et al 2018a ). Interestingly, no changes in phase have been observed after 6 headers, despite replicating the study design and dCA methodology (Jack et al 2022 ). The correlation between head impacts received and the change in dCA phase observed here suggests that a greater number of headers may have elicited such alterations.…”

“…Recent evidence demonstrates that heading in football may acutely alter dynamic CA (dCA) during repeated squat-stand transitions (Smirl et al 2022 ) and other metrics of cerebral blood flow regulation (Smirl et al 2020 ). However, our own work, which utilised fewer headers, did not identify any acute changes in dCA during repeated squat-stand manoeuvres, nor CVR–CO 2 to repeated breath holding or hyperventilation challenges (Jack et al 2022 ). Therefore, a dose–response relationship might exist regarding the number of subconcussive head impacts, and acute alterations in brain blood flow regulation.…”

“…This was repeated five times in total, interspersed by 40 s recovery. The CVR–CO 2 to repeated BH was quantified as the percentage increase in the greatest MCAv value above baseline following each breath hold attempt (BH MCAv% ), in line with previous work from our laboratory (Koep et al 2020 , 2021 ; Jack et al 2022 ). To better isolate the reactivity to carbon dioxide and minimise the influence of any changes in MAP or Valsalva manoeuvre on MCAv, individual breath hold attempts were removed from analysis if MAP increased by more than 15 mmHg.…”

“…These data, therefore, cannot be extrapolated to professional boxing, or other martial arts. Previous interventional studies in this field have attempted to standardise the head impacts—for example, launching a football at a designated speed (Jack et al 2022 ; Smirl et al 2022 ). In the absence of this control, the inclusion of instrumented mouth guards would be a valuable addition to better describe the nature of head impacts beyond the total number of blows to the head received (i.e., the magnitude and direction of accelerations).…”