How does the Cardiovascular System Work?

So how does the cardiovascular system work?

I think today’s post might bring you back to grade 11 biology class. And yea you probably didn’t pay attention back then, but I advise you to tune in now because understanding how the cardiovascular system works and integrates with other systems of your body can help you structure you cardio sessions more effectively.

Understand that the human body is composed of various systems that work together to helps us do the everyday things that we often take for granted. In my opinion, the cardiovascular system is one of the most impressive systems in the body, but it is so closely integrated with the respiratory system that you simply can’t talk about one without mentioning the other.

So let’s get started – how does the cardiovascular system work exactly?

As a trainer and gym rat, I find it important to have a general understanding of how our systems work in order to construct more effective and efficient ways of training the human body. In the same way that you’d be able to design a better car if you knew all the intricate components and how they worked, you can similarly create a better workout if you are familiar with the intricate systems you are dealing with. (Weak analogy but you get the picture)

The cardiovascular system is composed of the heart and a network of blood vessels that carry blood throughout the body.

Its main responsibilities include the following:

  • Circulating blood throughout the body,
  • Transporting nutrients, oxygen, carbon dioxide and waste products throughout the body.

But first, let’s tune in the respiratory system.

When we take in a nice, deep breath of air, the air travels through our trachea and enters the bronchial tree where it goes to our lungs. As you can see in the picture below, the ends of the bronchial tree consist of tiny sacs called alveoli-this is where the magic happens – gas exchange! Alveoli, which are wrapped up by tiny blood capillaries, transfer the oxygen and nutrients into the bloodstream by a little process known as diffusion. Alveoli also take carbon dioxide from the bloodstream and get rid of it via exhalation. Pretty fair and simple exchange if you ask me.

The Respiratory System

The oxygen is now inside the blood stream – this is where the cardiovascular system takes over.

The oxygen-rich blood leaves the lungs and enters the left side of the heart. It is then pumped to the body via arteries to supply various tissues with oxygen (and nutrients). See if you can follow the blood circulation in the image below.

Circulation of Blood Image Source: CYBEX Institute

The blood delivers the oxygen and nutrients to the working tissues of the body and picks up any waste for removal. Now the oxygen-poor blood returns to the right side of the heart via veins and is pumped to the lungs to become oxygenated again.

That’s the entire process and it continues to repeat itself day in and day out. At rest, this process takes about 20 seconds to complete.

Now, think about why this is important to know. How can this help improve your cardiovascular fitness?

Now that you understand how oxygen and nutrients cycle through the body, you can see that improving your cardiovascular fitness is all about improving the strength and efficiency of your heart.

As you continue to challenge your cardiovascular fitness with circuit training, sprint training, and tabata training, your heart will continue to be able to pump more blood per beat and per minute. This means it will be able to better deliver oxygen and nutrients to the working muscles during exercise.

On top of that, an efficient cardiovascular system knows how to distribute its oxygen and nutrients properly. Research shows that an efficient system can deliver over 80% of its oxygen and nutrients to the working muscles (as opposed to any other part of the body).

This is what you’re after.

These are things that you need to understand as you continue to work on your cardiovascular fitness. The human body is an amazing machine and we need to know how it works to be able to improve its functions. I hope this article has helped you gain a brief but valuable understanding of how the cardiovascular system works.

[If you’re looking for an extensive overview of how the cardiovascular system works, check out this really cool video.]

What are some ways you challenge your cardiovascular fitness? Please share in the comments below!

13 thoughts on “How does the Cardiovascular System Work?”

  1. Srdjan,

    Nice overview of the cardiovascular system. When you think about it in terms of its bodily function, you can really appreciate how important it is that this system runs optimally. I do mostly high intensity interval cardio and low intensity walking (not much in between).


    1. Alykhan, it’s amazing how much we take our body for granted.

      Just out of curiosity, how often do you do your HIIT cardio and how often do you do your low intensity walking?

      1. I do HIIT about 3x a week and low intensity walking about 3x a week also. Sometimes I’ll do them both on the same day. Ideally, I’d like to walk after doing HIIT. But most of the time, I end up just walking about 45 min or so during my off days.

          1. I rarely combine lifting and HIIT anymore. I’ll sometimes walk on my lifting days. The reason for this is on lifting days, I’m trying to build muscle so I’m eating a lot more and on cardio days, my goal is to burn fat, so I do a lot of fasted training.

            My traditional HIIT sessions are about 20-30 min. But I also play soccer and count that as HIIT because it’s a lot of sprinting. This could be anywhere from 1-2 hours.

            1. That makes sense.

              I know Rusty recommends doing HIIT right after a workout to boost HGH for optimum results. Like you, I (usually) don’t do this because my week is already filled with intense activity (i.e. variety of sports).

  2. The cardiovascular system is like a machine and system of pipes. That is the best analogy I like to use. You need to keep it active or they will clog up and eventually if you don’t use it you lose it…
    I also do HIIT anywhere from 2 to 3 times per week. I also do moderate pace cardio (elliptical or walking) 2 to 3 times per week.


    1. Hey Sam, great analogy. You definitely have to keep it active and provide your system with the right ‘fuel’ to ensure optimal function.

      You and Alykhan both seem to love your cardio :). Do you combine your HIIT sessions with resistance training?

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