During exercise, cardiac output may increase by more than 170% to meet the body’s increased O₂ demands. This increase in cardiac output increases blood pressure. But the accompanying increase in arterial pressure is relatively small—only about 40%. What limits this increase in blood pressure so that it doesn’t reach dangerously high levels during exercise?

Cardiac output                                  

Explanation:

Cardiac output, expressed in liters/minute, is the amount of blood the heart pumps in 1 minuteCardiac output is logically equal to the product of the stroke volume and the number of beats per minute (heart rate)Four determinants of cardiac output  includes:Heart rate : The heart rate is perhaps the simplest determinant of cardiac output to visualize;the faster the heart beats, the more blood can be pumped over a particular period of timeContractility : An increased contractility of the heart muscle results in increased cardiac outputPreload : It is the degree of myocardial distension prior to shortening,an increase in the distension of the ventricle will therefore result in an increase in the force of contraction which will increase cardiac outputAfterload : It is the force against which the ventricles must act in order to eject blood, and is largely dependent on the arterial blood pressure and vascular tone

Vasodilation is widening of blood  vessels caused by relaxation of smooth muscle cells in the vessel walls particularly in the large arteries, smaller arterioles and large veins  thus causing an increase in blood flow

Arterial dilation leads to  an immediate decrease in arterial blood pressure and heart rate

The relationship between mean arterial pressure, cardiac output and  total peripheral resistance gets affected by vasodilation

Vasodilation causes arterial diameter to increase in the exercising skeletal muscle which limits this increase in blood pressure so that it doesn’t reach dangerously high levels during exercise