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Cerebral blood flow (CBF) will increase from rest to ∼60% of peak oxygen uptake (VO(2peak)) and thereafter decreases in the direction of baseline resulting from hyperventilation-induced hypocapnia and subsequent cerebral vasoconstriction. It is unknown what happens to CBF in older adults (OA), who expertise a decline in CBF at relaxation coupled with a blunted ventilatory response during VO(2peak). In 14 OA (71 ± 10 12 months) and 21 younger controls (YA; 23 ± 4 years), we hypothesized that OA would experience much less hyperventilation-induced cerebral vasoconstriction and due to this fact an attenuated discount in CBF at VO(2peak). Incremental exercise was carried out on a cycle ergometer, whilst bilateral center cerebral artery blood flow velocity (MCA V (imply); transcranial Doppler ultrasound), heart charge (HR; ECG) and end-tidal PCO(2) (P(ET)CO(2)) have been monitored repeatedly. Blood pressure (BP) was monitored intermittently. From relaxation to 50% of VO(2peak), despite larger elevations in BP in OA, the change in MCA V(imply) was better in YA in comparison with OA (28% vs. 15%, respectively; P 70% of VO(2peak), the hyperventilation-induced declines in both P(ET)CO(2) (14 mmHg (YA) vs.
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