Author(s): HUANG, J., YAN, X., Institution: GUANGZHOU SPORT UNIVERSITY, Country: CHINA, Abstract-ID: 765

INTRODUCTION:
The present study aimed to determine whether high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and resistance exercise (RE) have different effects on endothelial function, arterial stiffness, and executive function (EF) in sedentary young individuals and explore the underlying mechanisms.
METHODS:
Sixty-three sedentary participants were randomly divided into the HIIT, MICT, RE, and control groups. Macrovascular and microvascular endothelial function were assessed by measuring brachial artery flow-mediated dilation (FMD) and fingertip reactive hyperemia index (RHI), respectively. Arterial stiffness was evaluated by carotid-femoral pulse wave velocity (cfPWV), brachial-ankle pulse wave velocity (baPWV), ankle-brachial index (ABI), and augmentation index (AIx). EF performance was evaluated through Stroop and N-back tasks. The functional near-infrared spectroscopy (fNIRS) was employed to measure the cortical activation and real-time oxyhemoglobin concentration (Oxy-Hb) changes in different cerebral regions.
RESULTS:
Compared to the baseline, mean shear rate, FMD, and RHI significantly increased and cfPWV significantly decreased in all three intervention groups but not the control group after 8 weeks of intervention. However, significant changes in FMD and peak diameter were seen in the HIIT group and the MICT group rather than the RE group, compared to the control group. In addition, a significant difference in the change of RHI was only observed between the control group and the HIIT group.
Compared to the baseline, the reaction time in the Incongruent Stroop task and the 3-back task significantly decreased after 8 weeks of HIIT and MICT. However, reduced reaction time in the Stroop interference task and the 2-back task were only observed in the HIIT group. During the Stroop task, the Oxy-Hb in the frontopolar area (FPA) significantly increased after 8 weeks of HIIT and MICT. Furthermore, significant increase in Oxy-Hb in the orbitofrontal area were only observed in the RE group, and significant increase in Oxy-Hb under the left of dorsolateral prefrontal cortex (L-DLPFC) and the right of dorsolateral prefrontal cortex (R-DLPFC) were only observed in HIIT. During the N-back tasks, the Oxy-Hb in the FPA region significantly increased after 8 weeks of HIIT and MICT. Furthermore, significant increases in Oxy-Hb under the L-DLPFC region were only observed in HIIT.
CONCLUSION:
Eight weeks of HIIT, MICT, and RE effectively improved macrovascular and microvascular endothelial function and arterial stiffness in sedentary young individuals. However, HIIT and MICT rather than RE efficiently activated certain brain regions such as FPA and DLPFC and improved EF. Among these three exercise types, HIIT seemed to be the most effective to improve vascular and cognitive function in this population. Importantly, enhanced vascular function by exercise training is pivotal to the improvement in cognitive function.