ECSS Paris 2023: OP-PN22
INTRODUCTION: This study examines the influence of high-intensity interval training (HIIT) on hemodynamics, a critical factor in cardiovascular health. Given that arterial stiffness, significantly influenced by hemodynamics, is a major risk factor for cardiovascular disease, the study employs color Doppler ultrasound technology to assess the effects of both acute and long-term HIIT on hemodynamics in healthy male subjects. In addition to this，the research explores the relationship between HIIT and hemodynamics, which encompasses blood flow and shear force, and is essential for maintaining arterial integrity. Regular physical activity, particularly HIIT, can enhance cardiovascular function by inducing arterial remodeling and optimizing blood flow dynamics. METHODS: Pre-experiment: Twenty male undergraduate students from the University of Westminster participated in a strength-oriented high-intensity interval training (HIIT) protocol to ascertain the optimal exercise loads for subsequent acute and long-term interventions. Acute Experiment: The identical cohort of 20 male undergraduate students from the University of Westminster underwent pre- and post-HIIT assessments to quantify carotid artery hemodynamic parameters, utilizing color Doppler ultrasound technology. Long-term Experiment: A total of 40 male undergraduate students from the University of Westminster were randomly assigned to either the experimental group (undergoing an 8-week HIIT program, three sessions per week) or the control group (sedentary). Comprehensive hemodynamic and cardiac function indices were measured in both groups prior to and following the intervention period. RESULTS: Acute HIIT: Acute high-intensity interval training (HIIT) induced a substantial increase in end-systolic and end-diastolic blood flow velocities, blood flow shear force, and blood flow rate. Concurrently, it led to a significant decrease in the resistance index and common carotid artery diameter. After 8 weeks of HIIT: Following an 8-week HIIT regimen, there was a notable increase in the E/A value, stroke volume, and cardiac output. However, no significant alterations were observed in the dimensions of the left ventricle. The HIIT group exhibited more pronounced improvements compared to the control group. Long-term HIIT: Prolonged HIIT enhanced hemodynamics by improving left ventricular diastolic function and augmenting common carotid blood flow and diastolic blood flow velocity. CONCLUSION: Acute HIIT: Acute high-intensity interval training (HIIT) elicits prompt favorable alterations in the hemodynamics of the carotid artery, such as an elevation in blood flow velocities and a reduction in the resistance index. Long-term HIIT: Prolonged high-intensity interval training (HIIT) substantially augments cardiovascular function through the enhancement of hemodynamic parameters and left ventricular function, thereby establishing a foundation for its application in cardiovascular rehabilitation.
Read CV YONGXUAN ZHAOECSS Paris 2023: OP-PN22
INTRODUCTION: Recent evidence suggests that the cerebrovasculature is better able to buffer acute increases, compared to decreases, in mean arterial pressure (MAP), and that dynamic cerebral autoregulation (dCA) may also be attenuated in females. Maximal sprint exercise induces large changes in systemic and cerebral hemodynamics, both during and following exercise. This may challenge dCA post-exercise, particularly during acute hypotension and in females, but this has not been studied. Therefore, the aim of this study was to 1) investigate the acute effect of maximal sprint exercise on dCA`in healthy young adults, and 2) explore sex differences in dCA pre- and post-exercise. METHODS: Twenty-one healthy adults (12 males (mean ± SD): 23.4±3.5 years, 177.7±5.5 cm and 73.3±9.7 kg; 9 females: 22.2±2.1 years, 166.9±5.9 cm and 63.1±9.9 kg) volunteered to participate in this study. During a single experimental visit, dCA was assessed at rest and 25 minutes following a maximal, 30 second Wingate test on a cycle ergometer. dCA was determined by forced oscillations in MAP during 5 minutes of repeated sit-stand manoeuvres, performed at 0.05 Hz. Middle cerebral artery blood velocity (MCAv) was measured using transcranial Doppler ultrasonography, and beat-to-beat blood pressure was measured using finger plethysmography. dCA was analysed using a multimetrics approach: 1) transfer function analysis (TFA), and 2) using a novel directional sensitivity metric, expressing the average time-adjusted (T, s-1) change in MCAv relative to MAP (ΔMCAvT/ΔMAPT) separately for each MAP direction. Two- and three-way ANOVAs explored the effects of exercise, sex and MAP direction on dCA. RESULTS: There was no effect of sex on any TFA outcome (P>0.05), so all participants were subsequently pooled together to investigate the effect of the Wingate on dCA. There were no pre versus post-exercise differences in gain (0.74±0.30 vs 0.70±0.20 cm.s-1/mmHg, P=0.51), normalised gain (1.12±0.41 vs 1.21±0.33 %/mmHg, P=0.22) or phase (0.97±0.23 vs 1.05±0.24 rad, P=0.17), but coherence was significantly greater following the Wingate (0.83±0.12 vs 0.90±0.12, P=0.042). ΔMCAvT/ΔMAPT did not differ by sex in either MAP direction or at any time point (P=0.64). Pre-exercise, ΔMCAvT/ΔMAPT was significantly higher during acute hypotension versus hypertension (1.0±0.4 vs 0.9±0.3 cm.s-1/mmHg, P=0.034), and this persisted post-exercise (0.9±0.2 vs 0.8±0.2 cm.s-1/mmHg, P=0.017). Wingate exercise had no effect on ΔMCAvT/ΔMAPT in either MAP direction (P=0.15). CONCLUSION: These novel findings: 1) Provide further support for hysteresis in the cerebral pressure-flow relationship, and show for the first time that these persist post-exercise, 2) Suggest that dCA remains intact following maximal sprint exercise in healthy young adults, and 3) Indicate males and females have comparable dCA, which are not differentially altered by acute maximal sprint exercise.
Read CV Max WestonECSS Paris 2023: OP-PN22