Older females but not males exhibit increases in cerebral blood velocity, despite similar pulsatility increases after high-intensity resistance exercise.

Abstract

Sex differences in resting cerebral hemodynamics decline with aging. Acute resistance exercise (RE) is a hypertensive challenge that might reveal sex-dependent abnormalities in cerebral hemodynamics. Thus, we hypothesized cerebral blood velocity and pulsatility responses to RE would be sex-dependent in older adults. Fourteen older females and 11 males [50-68 years] completed a high-intensity unilateral isokinetic knee flexion/extension exercise. Measurements were collected at baseline, immediately, 5-and 30-min post-RE. Blood pressure was measured via finger photoplethysmography. Mean middle cerebral artery blood velocity (MCAv) and pulsatility were assessed via transcranial Doppler ultrasound. Carotid pulsatility was obtained via duplex ultrasound. MCAv increased immediately after RE in older females (mean difference (d)= 6.02, 95% CI: 1.66 to 10.39 cm. s-1, p<0.001) but not in males (d= -0.72, 95% CI: -3.83 to 5.27 cm.s-1, p=0.99). Followed by similar reductions 5-min post-RE in older females (d= -4.40, 95% CI: -8.81 to -0.10 cm.s-1, p=0.045) and males (d= -6.41, 95% CI: -11.19 to -1.62 cm.s-1, p=0.003). MCAv pulsatility increased similarly in older females (d= 0.24, 95% CI: 0.11 to 0.40, p<0.001) and males (d=0.38, 95% CI: 0.20 to 0.53, p<0.001), persisting 5-min post-RE. Older females showed smaller increases in carotid pulsatility immediately after RE (d= 0.18, 95% CI: 0.03 to 0.38, p=0.01) than males (d=0.48, 95% CI: 0.26 to 0.68, p<0.001). An exercise-mediated hypertensive stimulus revealed differential sex responses in MCAv and carotid pulsatility but not in cerebral pulsatility. Cerebral pulsatility findings suggests a similar sex susceptibility to cerebrovascular abnormalities following an exercise-mediated hypertensive stimulus in older adults.