Lower Dynamic Cerebral Autoregulation following Acute Bout of Low-Volume High-Intensity Interval Exercise in Chronic Stroke Compared to Healthy Adults

Abstract

Fluctuating blood pressure during high-intensity interval exercise (HIIT) may challenge dynamic cerebral autoregulation (dCA), specifically post-stroke after an injury to the cerebrovasculature. We hypothesized dCA would be attenuated at rest and during a sit-to-stand, immediately following and 30 min after HIIT in individuals post-stroke compared to age- and sex-matched controls (CON). HIIT switched every minute between 70% and 10% estimated maximal watts for 10 min. Mean arterial pressure (MAP) and middle cerebral artery blood velocity (MCAv) were recorded. Resting dCA measured spontaneous fluctuations in MAP and MCAv via transfer function analysis. For sit-to-stand, time delay before an increase in cerebrovascular conductance index (CVCi = MCAv/MAP), rate of regulation, and %change in MCAv and MAP were measured. Twenty-two individuals post-stroke (age 60±12 yrs, 31±16 months) and twenty-four CON (age 60±13 yrs) completed the study. VLF gain (p=0.02, η2=0.18) and normalized gain (p=0.01, η2=0.43) had a group-by-time interaction, with CON improving immediately and 30 min after HIIT. Individuals post-stroke had impaired VLF phase (p=0.03, η2=0.22) immediately following HIIT compared to CON. We found no differences in the sit-to-stand. Our study showed lower resting dCA up to 30 min after HIIT in individuals post-stroke compared to CON while the sit-to-stand response was maintained.