What is Zone 2 Cardio and How Much Zone 2 Cardio Should I Be Doing?
In This Article:
What is cardio
What are cardio zones
Benefits of Zone 2 Cardio
How much Zone 2 cardio do you need
What is cardio?
I want to be clear about one thing. Cardio is not what you do to burn extra calories, cardio is an exercise that you do to improve your heart health.
Steady state, endurance cardio strengthens your entire heart and as a result, makes it healthier and more efficient.
Elevating your heart rate during strength workouts, HIIT workouts, and Tabata is not the same as endurance training. These types of resistance training simply enlarge the wall of the heart. (The left ventricle)
That’s because those types of workouts provide a brief and acute increase in cardiac load.
This is strengthening your heart(cardiac hypertrophy/thickness in the walls of your heart) but there’s a difference between a strong heart and a healthy heart.
In the same way that resistance training has significant impacts on muscle, bone, and connective tissue, endurance training impacts the heart, lungs, vascular system, and inside the muscle cells.
The body will adapt to imposed demand, and the most significant cardiovascular adaptations are a result of extended-duration activity and energy utilization.
The cardiovascular adaptations of endurance training are most directly correlated with good health.
Cardio Zones
Think of cardio being broken down into 5 zones as far as levels of intensity. The idea is to categorize the level of effort of metabolic and physical stress the body is going through at each phase.
Zone 1 is an easy recovery effort that is such a low intensity that it doesn't put a stressful load on any of the body's systems. Think of a very easy walk, it's easy enough to where you aren't forcing any adaptation in any part of the body. Your heart rate is barely going up, you probably aren’t sweating, and you can easily have a conversation.
Zone 2 is what a lot of people consider steady-state cardio. The idea of Zone 2 is a point where your body is staying out of heavy anaerobic systems but you are working a little harder than Zone 1.
You can still carry on a conversation but you are still working your heart. The load on your muscles is relatively low so you are getting a heart-training effect without crushing your body. It's the most sustainable way to get aerobic adaptations without subjecting your body to significant metabolic or orthopedic stress.
You can sustain Zone 2 for 35 minutes to 2 hours. If you were talking on the phone during Zone 2 cardio the person on the other end would know you are doing something but it wouldn't necessarily sound like you are in the middle of a workout.
Don’t think of Zone 2 as being so much of a heart rate zone as a level of intensity. Heart rate can vary with heat, training status, stimulants, and many other variables.
Ignore the equations that you find online that will give you your zone 2 and ignore what your smartwatch tells you is your zone 2.
Instead, use the talk test to find your zone 2. Find a 12-word sentence that you can memorize and repeat it out loud every few minutes during your cardio session. If you have to take a deep breath in between words or you can’t even get the sentence off at all then you are out of zone 2.
Zone 3 is the level of intensity that most people are at when they go out to run a 5K. Whether it be for fun or at an event, they usually run at a level of intensity that they can only sustain for 20 to 30 minutes and they feel much more beat up than zone 2.
Zone 4 is something like a really hard run that pretty much sucks right away but you can maintain it for 2 to 4 minutes. After 30 seconds or so you want it to be over, your heart rate is high, you are breathing hard, you are working really hard, but you can keep going for a couple of minutes.
Your legs are burning and it's unsustainable in the sense that your body is using energy and oxygen faster than it can replenish it. You eventually hit a wall because your energy is going down and your breathing is going up.
Zone 5 is an absolute all-out effort. It's the most you can output for 10 to 20 seconds. This is an all-out sprint or maximum effort on a bike or something similar.
Benefits of Zone 2
Unlike strength training and HIIT workouts, which only strengthen the wall of the heart, zone 2 cardio strengthens the entire heart.
It increases the vascular network that delivers blood to the heart and it improves the heart’s stroke volume. (Blood pumped per contraction)
This is where the Frank-Starling mechanism comes into play. The Frank-Starling mechanism is the heart’s physiological ability to change its contraction force.
Think of the heart as a pump and think about how much blood it can pump with each stroke or contraction. If the heart only expands a little bit on each pump and then contracts, it’s not pumping much blood.
As blood flows in through the veins, the heart expands. The more it expands, the more flexible it is, the more blood it can pump out on each stroke, and the more efficiently it pumps.
The heart needs time to stretch and fill. It’s only when you do low-intensity work that you get this full, filling effect. And when you do high-intensity work the heart doesn’t fill as much.
That’s because if a pump is moving too quickly it’s not filling fully each time. Imagine a bike pump that you are pumping quickly with small strokes. You aren’t getting much air in and aren’t able to pump very much air out. But when you hit that sweet spot with the bike pump you are putting out a lot of air with each pump.
During Zone 2 work, you are giving your heart the chance to fill almost all the way. You get stretching of the cardiac tissue and it will contract powerfully over and over again.
That’s how you get eccentric hypertrophy growth, development, and preload(the amount of blood and pressure coming in).
Afterload is the force of the blood coming out and preload is the amount of blood and pressure coming in.
Preload is very important to heart health and you improve that through Zone 2 cardio.
How Much Zone 2 Cardio Should You be Doing?
If you want to get the most out of Zone 2 cardio you should be doing at least 60 to 80 minutes of effective Zone 2 cardio each week. Top that off with a long walk on the weekends and you are looking at some serious health benefits.
During each training session, the first 10 minutes don’t count towards effective Zone 2 as it is just the warm-up.
Ultimately, you can break down your sessions however you want but here are my suggestions.
Two 45-minute sessions per week = 70 minutes of Zone 2 per week
Four 30-minute sessions per week = 80 minutes of Zone 2 per week
What are the Best Types of Zone 2?
For the most part, the type of zone 2 that you are going to do comes down to preference. You can use a stationary bike, an elliptical, a treadmill, a recumbent bike, or even swimming
I prefer a stationary bike because it is low-impact, but that’s me. The beauty of something like that is you can still do other things while you are getting your Zone 2 in. You can read on your Kindle, answer emails, or talk on the phone.
A treadmill is also great because you can use an incline to bump up the intensity because sometimes a slow, flat walk isn’t enough to get your heart rate up to where it needs to be.
I find it difficult for people to stay in zone 2 during a run or an outdoor bike ride so I don’t usually suggest those for zone 2 training. Depending on where you live you could hit a hill that makes you put in more effort and before you know it you are out of zone 2. And as far as running, it’s really hard to run outside slow enough to keep yourself in zone 2.
The best type of zone 2 for you is something that you have access to and can sustain.
You can also switch it up from time to time or even in one session. I would much rather you do 25 minutes on a stationary bike and then 25 minutes on an elliptical than do nothing at all.
Whatever you need to do to get it done, do that.
Wrapping Up
There are benefits to other types of cardio than just Zone 2 but Zone 2 is without a doubt the best type of cardio for heart health. If you have the time and energy to sneak in a HIIT workout once a week it won’t hurt.
And it’s certainly a good thing to have a strong heart from resistance training.
But to improve your overall health in the best way possible you want to make sure you are including Zone 2 into your routine.
It’s also worth noting that Zone 2 cardio will not hurt your strength training or weight-lifting. It will help it.
It will help you recover faster in between sets, it will make your sets more productive and higher quality.
I hope you learned something today. Personally, zone 2 cardio changed my life and I wish it was something I cared about much sooner in my fitness journey.
So no matter where you are in your journey, you can benefit from it too.
If you have any questions feel free to leave them in the comments and if you want first dibs on more information like this from me make sure to sign up for my newsletter below.
Fill out the short form below and I’ll also send you a free copy of my Full Body Mobility & Flexibility eBook.
