The Effect of Stroke on Middle Cerebral Artery Blood Flow Velocity Dynamics During Exercise

Abstract

Background and Purpose: Previous work demonstrates that older adults have a lower response in the middle cerebral artery velocity (MCAv) to an acute bout of moderate intensity exercise when compared to young adults. However, no information exists regarding MCAv response to exercise post-stroke. We tested whether MCAv response to an acute bout of moderate intensity exercise differed between participants 3 months post-stroke and an age-and sex-matched control group of older adults (CON). A secondary objective was to compare MCAv response between the stroke and non-stroke affected MCAv. Methods: Using transcranial Doppler ultrasound, we recorded MCAv during a 90-second baseline (BL) followed by a 6-minute moderate intensity exercise bout using a recumbent stepper. Heart rate (HR), end tidal CO2 (PETCO2) and beat-to-beat mean arterial blood pressure (MAP) were additional variables of interest. The MCAv response measures included: BL, peak response amplitude (Amp), time delay (TD), and time constant (τ). Results: The Amp was significantly lower in the stroke affected MCAv compared to CON (p < 0.01) and in the non-affected MCAv and compared to CON (p = 0.03). No between-group differences were found between TD and τ. No significant differences were found during exercise for PETCO2, and MAP while HR was lower in participants with stroke. (p < 0.01). Within the group of participants with stroke, no differences were found between the stroke-affected and non-stroke affected side for any measures. Discussion and Conclusions: Resolution of the dynamic response profile has the potential to increase our understanding of the cerebrovascular control mechanisms and test cerebrovascular response to physical therapy driven interventions such as exercise. Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1).

Self-Reported Omega-3 Supplement Use Moderates the Association between Age and Exercising Cerebral Blood Flow Velocity in Older Adults

“…Finally, there were no significant differences between groups in the proportion of individuals who reported taking vasoactive medications that could potentially influence blood flow, including anti-hypertensives and statins. Our primary outcome measure was mean MCAv during exercise [17][18][19][20]22]. We observed no outliers in the data as assessed by inspection of a boxplot.…”

“…Importantly, the exercise stimulus utilized was similar in intensity to walking up a flight of stairs [26] and thus reflective of physiological challenges incurred daily by the cerebral vasculature in these cognitively normal older adults. Impaired CBF metrics during exercise may reflect cerebrovascular dysfunction and brain pathology, as we have previously demonstrated a decreased CBF velocity response to exercise in individuals after ischemic stroke [18,19], with Alzheimer's-associated brain pathology [20], and in disease-free aging [45]. In the current study, we report data that suggest that supplementation with omega-3 fatty acids may be one potential avenue to counteract this decline in exercising CBF velocity, which could in turn improve brain health and function.…”

“…It has been reported that resting cerebral blood flow (CBF) decreases over time during healthy aging [9], and this decline is accelerated in individuals developing cognitive impairment such as Alzheimer's disease [10][11][12][13][14][15][16]. Additionally, our laboratory reported decreased CBF velocity both at rest and during exercise in people with chronic conditions such as atherosclerotic cardiovascular disease [17] and stroke [18,19]. Further, we found that cognitively normal older adults with elevated brain amyloid-β (Aβ) have a reduced CBF response during exercise compared to cognitively normal older adults with non-elevated brain Aβ [20], suggesting that the brain may receive less oxygen and fewer nutrients in people with dementia-associated pathology.…”

Middle cerebral artery velocity dynamic response profile during exercise is attenuated following multiple ischemic strokes: a case report

“…In addition, older women demonstrated a delayed response following exercise onset. We recently published individuals 3 months after MCA stroke have a significantly lower MCAv during moderate‐intensity exercise than sedentary, age‐, and sex‐matched adults (Kempf et al ). During recruitment for the larger study (Kempf et al ), one of our participants experienced two ischemic strokes.…”

“…We recently published individuals 3 months after MCA stroke have a significantly lower MCAv during moderate‐intensity exercise than sedentary, age‐, and sex‐matched adults (Kempf et al ). During recruitment for the larger study (Kempf et al ), one of our participants experienced two ischemic strokes. Therefore, the purpose of this case study is to describe the effect of MCA stroke on the cerebrovascular response to an acute bout of moderate‐intensity exercise and to characterize the response over time in this individual.…”