What is your Cardiovascular System?

Readers know I've wanted to share my recent experimentation with Heart Rate Monitors.  But first it is important to share some Anatomy (body structure) and Physiology (body function) about our hearts.

Your Cardiovascular System is your heart (cardiac), blood vessels (vascular), and circulating blood.  The wellness of these elements allows for oxygen transportation to your working tissues, blood pressure control, fluid balance, and body temperature regulation.   Pulmonary refers to the circulation of blood through your lungs; Systemic is the circulation of blood through your body.  Arteries (from the heart) and veins (to the heart) are smooth muscle and can change slightly increase or decrease blood flow or redistribute flow through the body.

What is one Cardiac Cycle?  The right side of your heart receives blood from your body and sends it to your lungs for oxygen uptake.  The left side receives oxygen-rich blood from your lungs and pumps it to your body.  The left and right volumes of your heart are the same, but the pressure is highest leaving your heart on the left to the body and lowest where it returns from your lungs on the right.

What is Blood Pressure?  1/3 of your Cardiac Cycle is blood flowing passively into the heart, or Diastole.  Systole is the other 2/3 of the cycle: the force of the ventricles (lower chambers of the heart) contracting.  When you begin walking and progress to running, Systole slightly increases and Diastole should remain the same or slightly decrease.  Both Systole and Diastole can improve (usually showing a decrease) within three months of beginning a regular cardiovascular program.

Did you know?  Plasma Volume increases by 10% within 24 hours of an endurance workout which increases return to the heart and load/fill before each heart contraction.

Stroke Volume is the amount a heart can fill and pump per heart beat.  This varies by gender (men have larger heart volume than women) and fitness level.  During events, the stroke volume of an athlete can be as much as 70% higher than untrained subjects for a similar heart rate.

To help you understand more:  An elephant has a huge stroke volume (large heart) and low heart rate.  A hummingbird has a tiny stroke volume (tiny heart) and high heart rate.  A baby has a lower stroke volume and higher heart rate than an adult; his/her heart rate slows as his/her heart and body grows larger.

With all other variables removed:  In adulthood, the maximum number of heart beats per minute decreases on average by about one beat per year.

Cardiac Output is the volume of blood pumped for a given heart rate each minute, both controlled by the nervous system and hormonal changes in the heart in response to the body’s demands.  Raise either heart rate or stroke volume and blood circulation increases.

How our bodies are limited: Oxygen Delivery or Oxygen Use?
During exercise above one’s aerobic capacity (where delivery meets demand), skeletal muscle can use oxygen quicker than our circulation can deliver it.  This is why some athletes turn to Blood Doping (artificial increase red blood cell numbers through injections) although it is highly dangerous and illegal.  The smart athletes can instead train at higher altitudes to increase the demand and production of red blood cells in a healthy and legal manner, the benefits of which occur after only one to two weeks but fade within three days of returning to lower altitudes.

Cardiovascular Drift:  As you aerobically exercise anywhere from 10-60 minutes, stroke volume decreases due to increasing demands from temperature regulation, decreasing hydration levels, and increasing muscle metabolism.  Heart rate will therefore increase to keep cardiac output constant.

Now you know some basics on what the cardiovascular system is all about, I’ll be sharing posts on:
  • How and Why to Monitor Your Resting Heart Rate
  • The Benefits of Warm Ups and Cool Downs on Heart Rate
  • Variables: What Changes our Heart Rate
  • How and Why to Use Heart Rate Monitors
  • Training Zones and How do you Calculate Yours
  • Training Tips and Special Considerations for Endurance Work
AND a page of the resources I’m using to bring you this valuable information.

Special thanks to Robergs and Keteyian's 2003 Fundamentals of Exercise Physiology 
for a majority of this post's A&P information.

PHEW!  This is why these posts are slow to be published… there is so much to know about how to achieve and maintain your best heart health.  But don't you feel smarter already?

Keep focused on our common goals:
Feeling better, living longer, and playing a whole lot more!


  1. Thanks for the tips Megan - I didn't know a lot of this stuff!

  2. Thanks for sharing these tip with us. Some great information here.

  3. thanks for share.


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