The Effects of Aging and Sex on Cerebral Blood Velocity in Response to Acute Resistance Exercise.

Total brain (i.e. cerebral) blood flow (BF) decreases with age, while blood pressure and the pulsatility of cerebral BF increases, which leads to greater prevalence of brain lesions, disability and cognitive impairment. Sex-related differences have also been observed in cerebral BF characteristics and blood pressure regulation throughout the aging process. The objective of our study was to examine the effects of age and sex on systemic vascular and cerebrovascular function following acute resistance exercise (RE). Young and older adults performed three sets of 10 repetitions of single leg flexion/extension exercise to induce a high-pressure stimulus. Systemic and cerebrovascular function was measured at rest, immediately, 5-, and 30-minutes post-RE. Our data indicates potential cerebrovascular dysfunction with aging, in that the older adults had a greater increase in pulsatility of cerebral BF. Furthermore, it also appears that more of this pulsatile energy is likely transmitted from systemic circulation through to the brain immediately following the high-pressure stimulus in older adults compared to young adults. While the older group had greater pulsatility in their BF response, they also had a lower overall response in cerebral BF (specifically-velocity of the BF) immediately after the stimulus. This may seem to be an impairment, but it could also be viewed as resiliency of the older brain, due to the larger increase in cerebral resistance, which may protect the cerebral tissue from hyperperfusion. Additionally, our findings suggest possible sex differences in the transmission of pulsatile velocity to the brain following an acute hypertensive stress. Older females appeared able to regulate cerebral circulation more efficiently compared to their age-matched male counterparts. This suggests that loss of estrogen with age may not contribute to disruptions in cerebral hemodynamics and regulation of cerebral BF in older females. This study is important as it contributes to the gap in our understanding of how age and sex both effect the transmission of BF to the brain and how brain BF is regulated under a high pressure condition. Further exploration of cerebral dynamics among aged males and females is required to determine its application in the detection, treatment and prevention of cerebrovascular disease.