Middle cerebral artery blood velocity and cognitive function after high- and moderate-intensity aerobic exercise sessions

This crossover study explored the acute effect of a session of high-intensity interval training (HIIT) or moderate -intensity continuous training (MICT) on middle cerebral artery (MCA) variables such as cerebral blood velocity, pulsatility index (PI) and resistivity index (RI) through transcranial Doppler (TCD), and cognitive function (CF -verbal fluency and Digit Span) in healthy young adults. Participants (26 healthy young adults, 13 women, 24 +/- 3 years) underwent two different randomized exercise sessions: (1) MICT (60 % heart rate reserve, HRR) and (2) HIIT (80 % HRR). MCA velocity, PI, RI, CF, and serum lactate were measured immediately before and after the sessions. HIIT demonstrated improved executive function/semantic fluency (20 %, p = 0.019), while both MICT and HIIT increased lactate (625 %, HIIT, p < 0.001, and 238 %, MICT, p < 0.001). Other assessments remained stable, except for reduced PI (p = 0.029) and RI (p = 0.023) after MICT, with no significant difference (pre-post for HIIT-MICT). Notably, cognition improvement correlated with lactate increase in HIIT (rho = 0.436; p < 0.001). Executive function/semantic fluency increased after HIIT relative to MICT. The findings show that there are no systematic out-of-normal changes in the cerebrovascular circulation of clinically healthy adults undergoing HIIT and MICT.