Post-Stroke Physical Activity Improves Middle Cerebral Artery Dynamic Response

Background: and Purpose: The primary aim was to characterize the middle cerebral artery blood velocity (MCAv) dynamic response to an acute bout of exercise at 3- and 6-months post stroke. As a secondary objective, we grouped individuals according to the MCAv dynamic response to the exercise bout as responder or non-responder. We tested whether physical activity, aerobic fitness and exercise mean arterial blood pressure (MAP) differed between groups. Methods: Transcranial Doppler ultrasound measured MCAv during a 90-second baseline (BL) followed by a 6-minute moderate intensity exercise bout. Heart rate (HR), MAP and end tidal CO 2 (P ET CO 2 ) were additional variables of interest. The MCAv dynamic response variables included: BL, time delay (TD), amplitude and time constant (τ). Results: Individuals enrolled in the study at 3 months post-stroke and the follow up visit commenced at 6 months post-stroke. Linear mixed model revealed no significant differences in our selected outcomes across between 3- and 6-months post-stroke. Individuals characterized as responders demonstrated a faster TD, higher amplitude, reported higher levels of physical activity and aerobic fitness when compared to the non-responders. No between group differences were identified for BL, τ or exercise MAP. In the non-responders, we observed an immediate rise in MCAv following exercise onset followed by an immediate decline to near BL values while the responders showed an exponential rise until steady state was reached. Conclusions: The MCAv dynamic response profile has the potential to provide valuable information during an acute exercise bout following stroke. Individuals with a greater MCAv response to the exercise stimulus reported regular participation in exercise than those who reported being sedentary.