Heart Fitness 101

Introduction

Our hearts can glow with joy, be hardened by anger, conflict with matters of the mind, drive us towards our goals, hold space for friends and family – and ultimately can efficiently pump blood through the roughly 60,000 miles of blood vessels in our body.

When we assume that the average heart rate is roughly 70 beats per minute (bpm) we could reason that the average person’s heart beats 100,800 times each day! That’s over 36 million beats each year! The amazing thing to consider here, is that we don’t have to account for every beat. Our heart beats when we are awake, sleeping, stressed, happy, mad, laughing, running, swimming, yodeling, and everything in between.

Our hearts are tireless workers, constantly pumping to ensure that we can enjoy our lives!

Below we will learn the basics about how the heart works, and how movement and exercise can help ourselves and our hearts out to be more efficient, stronger, and healthier – so that our entire body is ultimately more efficient, stronger, and healthier!

Specific topic outline:

  • Heart Anatomy 101 – How blood flows through your heart!
  • Heart Physiology 101 – Heart efficiency matters!
  • The benefits of training to keep your heart healthy

Heart Anatomy 101

You may have taken anatomy in high school, and if you did you may remember that the human heart has 4 chambers (2 atria and 2 ventricles). The ventricles are the larger bottom chambers that move the blood throughout the body when they contract, and the atria are the top chambers that contract to put the final fill of blood into the ventricles before the ventricles ship blood away from the heart.

Many physiologists and anatomists simplistically divide the heart’s chambers into the “left heart” and “right heart.” The left heart includes the left atrium and ventricle, and this heart pumps oxygenated, “clean” blood to the entire body (called systemic circulation). The right heart includes the right atrium and ventricle, and this heart pumps deoxygenated, “dirty” blood from the heart to the lungs so that the blood can get oxygenated and carbon dioxide can leave the body (called pulmonary circulation).

The simplified summary flow of blood looks like this:

“Dirty blood” from the body flows into the Right Atrium —> Right ventricle —> Lungs  (Pulmonary Circulation; Blue in the picture)

“Clean blood” enters the left atrium —> Left Ventricle —> The entire body (Systemic Circulation, Pink/Red in the picture)

Heart Physiology 101

In physiology (and healthcare), we are concerned with how much blood gets pumped with each beat, how saturated your blood is with oxygen, and how much of that oxygen gets used. These are very important things when you think about it…

The amount of blood that gets pumped with each beat is called your stroke volume (SV). When you consider your stroke volume over the course of a minute, you get your cardiac output (CO, or Q). Your cardiac output, then, is determined by your Stroke Volume (SV) and your Heart Rate (HR); SV * HR = CO. A fairly average cardiac output is 5L (or 5,000mL) of blood per minute. Your cardiac output and its components are really good determinant of the efficiency of your heart

Let’s bring this to real-life…

So let’s say a highly fit individual has a resting HR of 40 beats per minute (bpm) and their resting cardiac output is 5,000mL/min (5L/min). That means that their stroke volume must be 125ml per beat!

Compare this to an individual who is untrained or deconditioned. Let’s say their resting heart rate is 82bpm. At 82bpm, their stroke volume must be only 61ml per beat! This is literally less that half of the amount of the trained individual.

The takeaway here is that a healthy heart actually can move more blood with less energy being used. A heart that doesn’t have to work as hard is a happy heart for a multitude of reasons.

Now, to get a broader view of your body’s efficiency, exercise physiologists tend to look at your VO2 Max, or your maximal oxygen uptake/consumption. VO2 is a rather tricky concept to grasp at first blush, so I will do my best to keep it simple and applicable.

VO2 is measured relatively as mL/(kg*min) and absolutely as L/min.

VO2 can be found by using the Fick Equation by measuring these numbers in an individual who is working at maximum exertion, VO2 Max = CO * (Arterial Oxygen Content – Venous Oxygen Content)

There are ways to estimate VO2 using submaximal exercise, which is often more appropriate for people who may have cardiovascular or respiratory issues.

As you can see from the Fick Equation above, VO2 max is a measure of oxygen content as blood leaves your heart (arterial O2 content) and as blood returns to your heart (venous oxygen content). By measuring the amount of oxygen that leave and returns, we can measure how much oxygen your body actually used, and from this we can make predictions about aerobic performance and endurance.

An average VO2 is around 40 mL/(kg*min) for males and 30ml/(kg*min) for females.

Elite athletes, such as elite runners can have VO2 maximums around 85mL/(kg*min) for males and 77mL/(kg*min) for females.

The importance of maintaining a solid VO2 really becomes more important as we age, because without stimulation (movement/exercise) our VO2 maximums can drop pretty drastically as we age. In order to simply maintain an independent lifestyle as we age we need a VO2 of 13 mL/(kg*min). To enjoy our lives beyond independence alone as we age we should strive to maintain a VO2 above that 13 benchmark.

Benefits of training your heart!

That was a lot. If you made it here, good work! If you don’t have a biology background and you made it here understanding everything, even better work!

I’ll cut to the chase in this portion of the article to simply say that the benefits of training your heart (cardiovascular training) go far beyond the heart itself! Take a look…

  • Improved cardiovascular efficiency
    • Decreased heart rate
    • Increased stroke volume
    • More efficient cardiac output
    • Increased VO2 max
  • Improved performance in work, life, and sports
  • Reduced cardiovascular risk factors, such as:
    • Unhealthy body composition
    • Unbalanced blood lipid profile
    • High blood pressure
  • Reduced mental anxiety
  • Monitors weight management

Let’s Wrap this Up…

I think what I want to make more clear than anything, is that our hearts are absolutely amazing little pumps, and we should do our best to make their lives easier – in order to make our lives easier and healthier!

We can make our hearts stronger and more efficient through movement and exercise. By simply elevating our heart rate with varying levels of intensity several times a week, we can see marked improvements in our cardiovascular function!

Not only that, but we will also notice changes throughout our entire bodies! Improved weight management, improved body composition (i.e. we’ll look better naked), improved cholesterol and blood lipid levels, decreased stress/anxiety levels, and improved general performance!

 

More about the author, Mark.

Resources:
  1. Bandari, A. & Kwan, C. (2015) Clinically Relevant Exercise for the Primary Care Physician. Dynamic Health Professionals, LLC.
  2. Powers, S. & Howley, E. (2007) Exercise Physiology: Theory and Application to Fitness and Performance (6th ed). McGraw Hill.
  3. Robbins, P. (2008) Cardiorespiratory Training for Fitness. National Academy of Sports Medicine.
Cardiac Output and VO2 Numbers checked and acquired from:
  1. http://www.webmd.com/heart-disease/tc/cardiac-output-topic-overview
  2. https://en.wikipedia.org/wiki/VO2_max

 

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