Systolic blood pressure rises, whereas diastolic and mean pressure may rise slightly or remain constant. At the same time, peripheral vasodilation, particularly in skeletal muscle, causes a drop in calculated peripheral vascular resistance, even though total flow has increased substantially. Finally, A-V 02 diff. increases as tissue 02 extraction rises. Stroke volume levels off or may even fall somewhat at high heart rates due to inadequate ventricular filling time.
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