Intracranial Vascular Responses to High-Intensity Interval Exercise and Moderate-Intensity Steady-State Exercise in Children.
CM Tallon, RG Simair, AV Koziol, PN Ainslie, AM McManus

School of Health and Exercise Sciences, University of British Columbia

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. MCAV was increased above baseline in MISS after 75 seconds (5.8% [3.9%], P = .004) but was unchanged during HIIE. MCAV was reduced below baseline (-10.7% [4.1%], P = .004) during the sixth sprint of HIIE. In both conditions, MCAV remained 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.