Author(s): PLANTE, S., MARCOTTE-CHÉNARD, A., TREMBLAY, R., BOULAY, P., GERALDES, P., GAYDA, M., MAMPUYA, W., CHRISTOU, D., LITTLE, J.P., RIESCO, E. , Institution: UNIVERSITÉ DE SHERBROOKE, Country: CANADA, Abstract-ID: 1715

INTRODUCTION:
High-intensity interval training (HIIT) improves vascular function in individuals with type 2 diabetes (T2D). Although the underlying mechanisms remain poorly understood, these adaptations may partly result from repeated exposure to acute exercise-induced endothelial responses, that can be detected by changes in circulating biomarkers. However, HIIT bout duration is likely an underappreciated factor influencing these acute responses. The primary objective of this study was to compare the acute response of two HIIT protocols differing in interval duration and volume on circulating biomarkers related to endothelial responses in older women with T2D and hypertension.
METHODS:
Fifteen older women with T2D (69 [65-74] years) completed a randomised cross-over study with two conditions: 1) HIIT10: 10x1 min and 2) HIIT4: 4x4 min both at 90% of maximal heart rate with equivalent training load. Blood samples were collected before, immediately after and one-hour post-exercise. Plasma levels of endothelin-1 (ET-1), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and vascular endothelium growth factor (VEGF) were measured using ELISA.
RESULTS:
ICAM-1 and VCAM-1 levels increased immediately after HIIT10 (ICAM-1: 281 [219-334] ng/mL vs. 336 [262-428] ng/mL; VCAM-1: 591 [491-553] ng/mL vs. 671 [553-752] ng/mL; all p-values ≤ 0.03), whereas no significant changes were observed after HIIT4 (p> 0.05). No significant changes were observed for ET-1 or VEGF levels (all p-values ≥ 0.20) in both HIIT protocols.
CONCLUSION:
The transient increases in ICAM-1 and VCAM-1 levels observed following HIIT10 suggest that higher number of intervals influences acute endothelial responses, potentially through a higher density of intensity transitions and an intermittent hemodynamic stress, independent of training load.