Cerebral blood velocity responses during and after sprint interval exercise in healthy young adults.

This study investigated the middle (MCAv) and posterior (PCAv) cerebral artery blood velocity and end-tidal carbon dioxide (PETCO2) responses during sprint interval exercise (SIE). We also examined the relationships between MCAv, PCAv and blood pressure during the 60 min post SIE. Fourteen healthy adults completed four 30 s maximal cycle sprints, each separated by 4 min of unloaded cycling. MCAv and PCAv demonstrated a rapid increase followed by a return towards the initial baseline values during each sprint. The increase during the first sprint (MCAv: +31.9% ± 19.9%, PCAv: +32.5% ± 30.6%) was always greater than subsequent sprints (p ≤ 0.039). Each sprint was followed by a transient increase in MCAv and PCAv, which mirrored PETCO2. SIE was followed by 60 min of hypocapnia, and blood pressure was significantly lowered 10-20 and 40-55 min post SIE. However, resting MCAv was not altered, and PCAv was only lower 5 min post SIE. Resting MCAv phase and gain, and PCAv phase were largely unaltered apart from the first 5 min post SIE. The ability to buffer changes in blood pressure during repeated squat-stand maneuvers remained intact 60 min post SIE, although a greater fall in MCAv and PCAv was noted during a single sit-to-stand transition at this time.