What is cardio, really?
Cardio = “cardiovascular exercise”.
Cardio + Vascular.
”Cardio” meaning heart.
”Vascular” meaning circulatory system.
By the most narrow definition, when we’re “doing cardio” what we’re training is the heart and the rest of the circulatory system to distribute resources and remove waste products to and from every tissue in the body.
Sounds simple enough.
But there’s a bit more nuance to it, of course.
Energy Systems
Your body has three main ways it uses energy for fuel, and it matters because what kind of fuel and how much you need dictate how hard the pump (your heart) works to get resources out to the body.
You probably don’t need the full technical names, so we’ll call these high intensity, moderate intensity, & low intensity.
High Intensity
Go outside (or imagine it in your mind) and sprint as hard as you possibly can. How long do you think you’ll last before you have to slow down a bit?
Most people it’s about 15 or 20 seconds. That’s the threshold at which your body has used up the available energy at the cellular level within your muscles. If you stopped and waited for 5 minutes or so you’ll probably be able to go again. That’s because your cardiovascular system kicks in, buffers the waste products, and brings stored energy from your liver to the muscles.
As you keep repeating the activity you’re using up those stored fuel and other resources. Eventually you’ll see performance decline over time.
Moderate Intensity
Next, you’ve got medium intensity efforts. You’re not quite in an all-out sprint, but you’re working harder than a stroll. You couldn’t maintain it forever; because just like repeating sprints, you’ll eventually burn through your stored energy and fall behind on buffering waste products.
If, however, you dialed back on the intensity for a little while your cardiovascular system would catch up, buffering and restoring resources so you can go again.
This is climbing rolling hills on the bike or doing 400m repeats on the track.
Low Intensity
Low intensity efforts are also called “steady state cardio”. This is walking up hills, jogging, hiking, cycling, skating - anything were you’re huffing and puffing but could still chat a bit.
In this energy system your heart and circulatory system are able to keep up with demand, you’ve got plenty of fuel in the tank (the tank being your liver) and you’re cruising along.
(Side note - if you google it you’ll find 4 main ways people divvy up cardio. I’ve simplified it here since this article is for the novice. It’s not that those other things are wrong; this is just how I teach it to clients.)
Why is cardio important?
No doubt you know a healthy heart and circulatory system are part of a well-balanced movement practice. But why!?
Regular cardio helps your heart be more efficient, improves your bodies abilities to use up the resources being transported (in this case, oxygen), and improves blood flow throughout the body.
You also increase the amount of blood the body produces, reducing high blood pressure, and cardio increases the elasticity of vascular walls, which also improves blood pressure and helps prevent blood clots. Those clots could lead to heart attacks and strokes… which is why cardio helps prevent them.
Cardio helps treat metabolic disease - so Type 2 diabetes, increasing mitochondrial density (part of a healthy metabolism), and even has been shown to decrease risk of some cancers.
And all that together is why cardio is tied to decreasing all cause mortality (translation: pushing off when you’ll die).
BUT WAIT! THERE’S MORE!
Moderate and light intensity cardio has been tied to increased sensitivity to serotonin, boosted mood, decreased depression, and lowered anxiety recurrance.
Higher intensity cardio has been shown to increase dopamine production and therefore improve focus and self-regulation.
All of which means that there are emotional and mental well-being benefits, too.
Recommendations Around Cardio
So where do you start? Here are a few factors to consider:
Choosing the “Mode”:
Mode is the “what” - like cycling, dancing, running, etc. Here’s a few ways to think about mode when you’re not sure what you want to do:
If you’ve got something you know you like - research shows when we choose activities we like, or we do them with people we like, we’ll repeat them more often and more consistently.
Choose what’s easiest or most accessible - by starting with what’s accessible you’re able to build a more consistent habit. If joining a gym or buy equipment is outside your budget it’s okay to go with what can work for now.
Not sure? Time to experiment - grab a friend or your partner and start trying things. Take a dance class. Try hot yoga.
What intensity?:
Consider what’s written above about different effects of different types of cardio. If your goal is for your mental and emotional health, low and moderate intensity is a’ok. If you want to boost self-control, focus, or deal with anxiety higher intensities can be helpful. Or, do what you know your body likes.
The caveat: too intense, too often can lead to over training. Give yourself time to build up both the intensity of effort and the recovery between days of higher intensities.
How often?
The American Heart Association recommends 150 minutes per week of moderate intensity activity or 75 minutes of high intensity.
Translation: You could walk like you’re a bit late for 30 minutes every day and you’re golden. You could take 1 HIIT class and do 1 kettlebell workout per week and you’d be good.
That all seem overwhelming?
START WHERE YOU ARE!
Starting to do a bit is lightyears better than doing nothing. Along the way you’re going to learn about yourself and what works for you, and that’s invaluable.
You got this!
~ Coach Dar
PS - Questions? Leave em in the comments for future article fodder.