Intracranial Vascular Responses to High-Intensity Interval Exercise and Moderate-Intensity Steady-State Exercise in Children

Abstract

Purpose:To understand the extent different types of acute exercise influence cerebral blood flow during and following exercise in children.Methods:Eight children (7–11 y; 4 girls) completed 2 conditions: high-intensity interval exercise (HIIE; 6 × 1-min sprints at 90% watt maximum) and moderate-intensity steady-state exercise (MISS; 15 min at 44% watt maximum). Blood velocity in the middle cerebral artery (MCAV) and heart rate were assessed continuously. The partial pressure of end-tidal carbon dioxide and mean arterial pressure were assessed at baseline and following exercise.Results:Percentage of maximum heart rate during HIIE was 82% (4%), compared with 69% (4%) during MISS. MCAVwas increased above baseline in MISS after 75 seconds (5.8% [3.9%],P × .004) but was unchanged during HIIE. MCAVwas reduced below baseline (−10.7% [4.1%],P × .004) during the sixth sprint of HIIE. In both conditions, MCAVremained below baseline postexercise, but returned to baseline values 30-minute postexercise (P < .001). A postexercise increase in mean arterial pressure was apparent following HIIE and MISS, and persisted 30-minute postexercise. Partial pressure of end-tidal carbon dioxide declined post HIIE (−3.4 mm Hg,P < .05), but not following MISS.Conclusion:These preliminary findings show HIIE and MISS elicit differing intracranial vascular responses; however, research is needed to elucidate the implications and underlying regulatory mechanisms of these responses.