Factors Affecting Cardiac Output

For every individual there are factors that should be taken into consideration when undergoing exercise and other physical activities. 

These are (CO) cardiac output, the (BV) stroke volume and heart rate.  These should be within reference values in relation to a person’s age, weight, height and his existing health condition. 

This is a significant fact that anyone who exercises should know.  You don’t just run around in circles or jog around daily without being aware that you have to monitor too these different factors.

Cardiac output is the amount of blood coming from the ventricles into the aorta per minute; while the stroke volume is the amount of blood coming from the ventricles for each heart contraction.  

The heart rate is the number of times that the heart beats per minute.  Normally, it is around 100 bpm (beats per minute).  This however varies according to the activity that we are engaged in. 

It is important to know these as they are all related to the cardiac output.

Any activity that increases heart rate will also increase your cardiac output. 

These are some factors that regulate cardiac output, stroke volume and heart rate:

Autonomic nervous system

When nerve impulses are sent to the medulla, a part of the brain, the autonomic nervous system is activated and receptors will then cause blood pressure changes, etc.

Epinephrine and norepinephrine (hormones secreted in the adrenal medulla gland) 

      These are released into the blood stream when there is anxiety, stress or increased physical activity.  These hormones promote the increased pumping of the heart and stroke volume, therefore increasing cardiac output.

Age

An infant has a higher heart rate than adults, usually at 115 beats per minute.  This gradually decreases and stabilizes to around 100 bpm as the person matures.

Gender

Females have a usually higher resting heart rate than male adults.

Physical fitness

A physically active person usually has a resting heart rate at around 50 bpm.

Body temperature

Increase in temperature will also increase your cardiac output.

It is therefore important that a person should be aware of these factors, to avoid applying undue stress and pressure on the heart muscles.