title: Relationship between aerobic endurance training and dynamic cerebral blood flow regulation in humans.
abstract: The incidence of orthostatic intolerance is elevated in endurance-trained individuals. We sought to test the hypothesis that aerobic endurance training is associated with an attenuated control of the cerebral vasculature. Endurance trained (ET, n = 13) and age-matched untrained (UT, n = 11) individuals (peak O2 consumption, mean ± SEM; 63 ± 1 vs 42 ± 1 mL/min/kg, P < 0.05) were examined while supine and seated upright. Dynamic cerebral autoregulation (CA) was assessed by calculation of the rate of regulation (RoR) from the arterial blood pressure (ABP) and middle cerebral artery (MCA) mean blood velocity (V mean ) responses to a bilateral thigh cuff release, which evoked a transient hypotension. Cerebral oxygenation (oxyhemoglobin; HbO2 ) was determined with near-infrared spectroscopy. When seated upright, cuff release evoked a greater decrease in ABP (P < 0.001), MCA V mean (P = 0.096) and HbO2 (P < 0.001) in ET compared with UT. However, RoR was similar in ET and UT individuals while seated upright (to 0.193 ± 0.039 vs 0.129 ± 0.029/s, P > 0.05), and there was no significant difference in the relative change in RoR from the supine to upright positions (ΔRoR: -65 ± 7 and -69 ± 7%, for ET and UT, respectively). These findings suggest that aerobic endurance training is not associated with an attenuation in dynamic CA.
authors.affiliation: Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan; Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo-shi, Yamanashi, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Ichikawa
authors.forename: T
authors.initials: T
authors.lastname: Miyazawa
authors.forename: M
authors.initials: M
authors.lastname: Horiuchi
authors.forename: T
authors.initials: T
authors.lastname: Kitama
authors.forename: J P
authors.initials: JP
authors.lastname: Fisher
authors.forename: S
authors.initials: S
authors.lastname: Ogoh
mesh_terms: D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007022:Hypotension / Q000209:etiology*; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D054971:Orthostatic Intolerance / Q000209:etiology*; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D013055:Spectrophotometry, Infrared / Q000295:instrumentation / Q000379:methods; D014463:Ultrasonography; D055815:Young Adult
keywords: middle cerebral artery blood velocity; orthostatic stress; postural effect