Factors that affect cardiac output in a healthy patient include heart rate, change in position and certain activity of the nervous system, according to Vascular Concepts. Cardiac output refers to the volume of blood the heart pumps each minute.
Cardiac output is calculated by multiplying heart rate by stroke volume, according to WebMD. In this equation, the heart rate is the number of times the heart beats each minute, and the stroke volume is the amount of blood the heart pumps with each beat. A normal cardiac output is about 5 to 6 liters per minute, which maintains a blood pressure that provides adequate blood flow to the brain and other vital organs.
During exercise, the body requires a higher cardiac output than it does at rest because the muscles need more oxygen, explains WebMD. The body responds to exercise by making the heart beat faster to deliver more blood throughout the body. Stroke volume also increases as the heart pumps more forcefully and allows more blood to enter the left ventricle before it contracts. This increase in heart rate and stroke volume during exercise can lead to a cardiac output that is three or four times greater than normal.