ABSTRACT

Examine the effects of incremental and submaximal exercise on structural and hemodynamic changes in the brachial artery flow parameters using Doppler ultrasonography.

Twenty four healthy sedentary males (aged 19.54±0.59) performed submaximal (15 minutes heart rate to 75% maximal) and incremental (workload was increased 20W every 3 minutes until exhaustion) exercises by upper extremity ergometer. Before and after exercises the brachial artery diameter, peak systolic maximum velocity (Vmax), end-diastolic minimum velocity (Vmin) and time-averaged mean flow velocity (Vmean), volume blood flow and flow waveform patterns were recorded in a controlled environment.

The diameter of the brachial artery, flow velocities, and blood flow increased significantly after each exercise protocol (p<0.001). The Vmax (p<0.05), Vmean (p<0.01), and volume blood flow (p<0.01) after the incremental exercise were significantly higher than those measured after the submaximal exercise. However, no significant differences were noted between the two exercise protocols when arterial diameters and Vmin were concerned. The flow pattern was monophasic in all subjects after incremental exercise. Nevertheless, the flow pattern remained triphasic in two of the subjects after submaximal exercise.

Blood flow velocities played important role in hemodynamic mechanism than conduit arterial diameter during arm exercises. Changes in conduit artery diameter did not significantly contribute to blood flow increase during high and moderate intensity exercises. There is minimal variation in waveform shapes of normal individuals after exercise. Doppler ultrasonography proved a practical tool in the studies of the dynamic responses of blood flow and vascular resistance during rest and exercises.

Keywords: Doppler ultrasonography, brachial artery, flow parameters, waveform analysis, flow-mediated dilation