Effects Of Different Intensities Of Exercise On Common Carotid Arterial Hemodynamics

Objective: The purpose of this study was to investigate the acute effects of cycling of different intensity on common carotid arterial hemodynamics in healthy young men,to provide effective hemodynamic parameters for the adjustment of acute aerobic exercise to common carotid artery function,and to provide a basis for making exercise prescriptions for healthy adults.Methods: 32 healthy young men(Age: 19.41±0.55 years;Height: 175.06±6.13 cm;Weight: 66.72±8.95 kg)were recruited in this study.Subjects attended the laboratory on five occasions and undertook 20 minutes of cycling at 40%,50%,60%,70% and 80% of their heart rate reserve.The targeted heart rates were calculated using the Karvonen formula.To avoid confounding effects,the trials were separated by 7 days.Center-line velocity and arterial inner diameter waveforms were examined before,3 min,15 min and 30 min post exercise by color Doppler ultrasound imaging.Synchronously,blood pressure and heart rate were measured using electronic sphygmomanometers at the left brachial artery.Results:1.Effects on elasticity and diameter of the common carotid artery: Compared to baseline,the pressure-strain elastic modulus and arterial stiffness were both higher after acute cycling exercise intervention,,and the maximum,mean and minimum diameters were reduced.With the increase of exercise intensity,the pressure-strain elastic modulus and arterial stiffness increase,and the mean and minimum value of artery diameter decrease.2.Effects on blood flow rate to brain: After acute cycling,heart rate was higher than that at rest.The maximum and mean values of center-line velocity and flow rate increased,and the minimum value decreased.With the increase of exercise intensity,the maximum and mean value of the heart rate and center-line velocity increased,and the minimum value of center-line velocity and flow rate decreased.3.Effects on hemodynamic parameters: Mean and diastolic blood pressure increased after acute cycling exercise compared with resting state.Mean and diastolic blood pressure were slightly lower than baseline after 30 minutes of recovery.Compared with at-rest state,the maximum and mean wall shear stress were higher,while,the minimum wall shear stress was lower.Acute cycling increased oscillatory shear index and pulsatility index,and decreased dynamic resistance and peripheral resistance.With the increase of exercise intensity,the mean blood pressure and diastolic pressure decreased.The maximum and mean wall shear stress increased.The minimum value of the maximum and mean wall shear stress decreased.The oscillatory shear index and pulsatile index increased,and the dynamic resistance and peripheral resistance decreased.Conclusion: After acute cycling exercise,the carotid artery elasticity and diameter decreased.The greater the intensity of exercise intervention,the greater the changes of arterial elasticity and diameter,and the longer the recovery time of arterial elasticity.After acute cycling exercise,the maximum and mean blood flow velocity increased,the cerebral blood supply state was better,and the recovery was faster.After acute cycling exercise,the blood supply to the brain was better,and the recovery was faster.With the increase of exercise intensity,the blood supply to the brain was better.Acute cycling exercise can induce hemodynamic responses.The changes in hemodynamic parameters and the recovery status were directly affected by the intensity of exercise.With the increase of exercise intensity,the change of hemodynamic parameters increases.