Aerobic Exercise Acutely Improves Dynamic Cerebral Autoregulation During Brain Activation

PURPOSE: Cognitive function is temporarily improved by acute aerobic exercise,especially clinical high-intensity interval exercise (cHIIE; four 4 min bouts ofhigh-intensity exercise) (Tsukamoto et al. 2016). Meanwhile, dynamic cerebralautoregulation (dCA) is an important cerebrovascular mechanism to maintainrelatively constant cerebral blood flow (CBF) against the rapid fluctuations inperfusion pressure, but it is impaired during cognitive tasks (causing brain activation) due to cerebral vasodilation (Ogoh et al. 2018). Although it has been demonstrated that dCA is not changed by aerobic exercise (Tsukamoto et al. 2019), which improves cognitive function (Tsukamoto et al. 2016), the impact of aerobic exercise on the brain activation-induced dCA impairment remains unclear. The purpose of the present study was to investigate the changes in dCA during a cognitive task prior to following different types of aerobic exercise. 
METHODS: Nine healthy male subjectsperformed three trials in a randomized crossover order; moderate-intensity continuous exercise (for 40 min), low-volume HIIE (lvHIIE; ten 1 min bouts of high-intensity exercise), and cHIIE protocols. The participants performed a 5 min color-word Stroop task (cognitive task) before, immediately after, and 30 min after each exercise bout. Middle cerebral artery blood flow velocity (Transcranial doppler ultrasonography) and arterial pressure (Finger photosplethysmography) were continuously measured to determine dCA using transfer function analysis, and dCA was estimated at rest and during each cognitive task. 
RESULTS: Before exercise, transfer function phase inthe very low-frequency (VLF) was decreased during cognitive task compared to the resting measurement (P < 0.01), indicating that there was brain activation-induced dCA impairment. However, VLF phase during the cognitive task immediately after exercise was higher than before (P < 0.01) and 30 min (P < 0.01) after exercise regardless of exercise protocol, indicating that dCA impairment during the cognitive task was blunted immediately after exercise. 
CONCLUSIONS: The brain activation induced dCA impairment is attenuated immediately after exercise. This result implies that aerobic exercise improves dynamic CBF regulation in response to brain activation during a cognitive task.