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.
Christine M. Tallon, Ryan G. Simair, Alyssa V. Koziol, Philip N. Ainslie and Alison M. McManus
Cindy H.P. Sit, Thomas L. McKenzie, John M.G. Lian and Alison McManus
This study compared physical education (PE) and recess in two markedly different special schools for children with mild intellectual disabilities; one school had a reputation for focusing on sports (High Sport Focus-HSF) and the other did not (Low Sport Focus-LSF). Data were collected in 24 PE classes and 48 recess periods using a validated observation system. During both PE and recess, HSF students engaged in physical activity (PA) at greater intensity levels, but LSF students accrued more total activity min. Differences in PA during PE between the schools were associated with both lesson context and teacher behavior. The results suggest written (e.g., scheduling) and unwritten policies within schools affect children’s activity levels.