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BackgroundAccumulative excessive physical load elevates central arterial stiffness and smooth muscular tone of peripheral vascular beds in endurance athletes. The aim of this study was to test the hypothesis that a brief series of soccer matches would increase central arterial stiffness and arterial wave reflection from the periphery in young female football players.MethodsFifteen subjects (17.2 ± 0.7 years, mean ± SD) participated in four matches over five consecutive days (one match per day, with two consecutive days of matches followed by one rest day, repeated twice) in the Youth Girls Soccer Tournament, either as starters or substitutes. Heart rate, blood pressure (BP), and the second derivative of the photoplethysmogram (SDPTG) were assessed the night before and 4 h after each match. The ratios of the first and second descending waves to the first ascending wave of SDPTG (B/A ratio and D/A ratio) were calculated as indices of central arterial stiffness and peripheral wave reflection, respectively. The intra-individual relationship among interest variables was evaluated using the repeated-measures correlation analysis (rmcorr).ResultsPost-match D/A ratio, systolic and diastolic BP were lower compared to the pre-match value, while the B/A ratio did not change significantly. Heart rate was higher post-than pre-match. Rmcorr demonstrated significant intra-individual correlations of the D/A ratio with diastolic BP (rrm = 0.259, P = 0.008) and heart rate (rrm = −0.380, P< 0.001).ConclusionContrary to our hypothesis, a brief series of matches did not increase central arterial stiffness in young female football players. Instead, the matches induced a repeated, temporary attenuation of arterial wave reflection. This attenuated arterial wave reflection from the periphery appeared to be associated with reduced diastolic BP and a compensatory increase in heart rate.

Cerebrovascular reactivity (CVR) to changes in the partial pressure of arterial carbon dioxide (PaCO2) is an important mechanism that maintains CO2 or pH homeostasis in the brain. To what extent this is influenced by gravitational stress and corresponding implications for the regulation of cerebral blood flow (CBF) remain unclear. The present study examined the onset responses of pulmonary ventilation (V̇E) and anterior middle (MCA) and posterior (PCA) cerebral artery mean blood velocity (Vmean) responses to acute hypercapnia (5% CO2) to infer dynamic changes in the central respiratory chemoreflex and cerebrovascular reactivity (CVR), in supine and 50° head-up tilt (HUT) positions. Each onset response was evaluated using a single-exponential regression model consisting of the response time latency [CO2-response delay (t0)] and time constant (τ). Onset response of V̇E and PCA Vmean to changes in CO2 was unchanged during 50° HUT compared with supine (τ: V̇E, p = 0.707; PCA Vmean, p = 0.071 vs. supine) but the MCA Vmean onset response was faster during supine than during 50° HUT (τ: p = 0.003 vs. supine). These data indicate that gravitational stress selectively impaired dynamic CVR in the anterior cerebral circulation, whereas the posterior circulation was preserved, independent of any changes to the central respiratory chemoreflex. Collectively, our findings highlight the regional heterogeneity underlying CBF regulation that may have translational implications for the microgravity (and hypercapnia) associated with deep-space flight notwithstanding terrestrial orthostatic diseases that have been linked to accelerated cognitive decline and neurodegeneration.