New Findings What is the central question of this study? Does habitual resistance and endurance exercise modify dynamic cerebral autoregulation? What is the main finding and its importance? To the authors` knowledge, this is the first study to directly assess dynamic cerebral autoregulation in resistance-trained individuals, and potential differences between exercise training modalities. Forced oscillations in blood pressure were induced by repeated squat-stands, from which dynamic cerebral autoregulation was assessed using transfer function analysis. These data indicate that dynamic cerebral autoregulatory function is largely unaffected by habitual exercise type, and further document the systemic circulatory effects of regular exercise. Abstract Regular endurance and resistance exercise produce differential but desirable physiological adaptations in both healthy and clinical populations. The chronic effect of these different exercise modalities on cerebral vessels` ability to respond to rapid changes in blood pressure (BP) had not been examined. We examined dynamic cerebral autoregulation (dCA) in 12 resistance-trained (mean±SD, 25 ± 6 y), 12 endurance-trained (28 ± 9 y), and 12 sedentary (26 ± 6 y) volunteers. The dCA was assessed using transfer function analysis of forced oscillations in BP versus middle cerebral artery blood velocity (MCAv), induced via repeated squat-stands at 0.05 and 0.10 Hz. Resting BP and MCAv were similar between groups (interaction: both P=0.544). The partial pressure of end-tidal carbon dioxide (PETCO2) was unchanged (P = 0.561) across squat-stand manoeuvres (grouped mean for absolute change +0.6 ± 2.3 mm Hg). Gain and normalised gain were similar between groups across all frequencies (both P=0.261). Phase showed a frequency-specific effect between groups (P = 0.043), tending to be lower in resistance trained (0.63 ± 0.21 radians) than in endurance trained (0.90 ± 0.41, P = 0.052) and untrained (0.85 ± 0.38, P = 0.081) at slower frequency (0.05 Hz) oscillations. Squat-stands induced MAP perturbations differed between groups (interaction: P = 0.031), with greater changes in resistance (P < 0.001) and endurance (P = 0.001) compared with sedentary at 0.05 Hz (56 ± 13 and 49 ± 11 vs. 35 ± 11 mm Hg, respectively). The differences persisted at 0.1 Hz between resistance and sedentary (49 ± 12 vs. 33 ± 7 mmHg, P < 0.001). These results indicate that dCA remains largely unaltered by habitual endurance and resistance exercise with a trend for phase to be lower in the resistance exercise group at lower fequencies.
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