Cardio Fitness & Endurance: Unlock Benefits Of Zone 2 Training

An Unavoidable & Crucial Component Of Longevity

Let’s be real – a lot of people hate cardio. It’s hot, sweaty and creates a sense of breathlessness that feels like we’re having an anxiety attack.

Welcome to the world of cardiovascular fitness.

What is cardio fitness anyway? It’s a measure of how efficiently your body can deliver oxygen to your muscles, and how efficiently your muscles can extract that oxygen, and use it for everyday movements like walking, running, swimming etc. The more “aerobically fit” you are, the more energy you will have for whatever you enjoy doing.

A study in JAMA in 2018 found that having a higher VO2 max (aerobic fitness) was associated with lower mortality (death) from all causes. In fact, if you’re in the bottom 25% of VO2 max scoring you’re four times more likely to die from all causes than somebody who scores in the top 25%. Poor cardiovascular fitness puts you at greater risk of death than smoking. Insane.

Basically, it’s important.

For the purposes of maximising our health, we’re interested in two kinds of cardio.

  1. Long, steady endurance work (Zone 2)
  2. Maximal aerobic efforts (VO2 max work)

In this article we’re going to be covering a real sweet spot for improving your fitness and endurance without overtraining and burnout: Zone 2 training. All the benefits of better cardiovascular health without the blood, sweat and tears that those high-intensity workouts have been giving you.

Part 1: Understanding How Your Body Works

TL;DR – Our body has two different fuel sources. Fat is very efficient, but low-powered. Glucose is high-powered but very inefficient. Our ability to use both types of fuel is key to metabolic health.

I’m over-simplifying this process slightly, but nobody wants a biochemistry lecture and this is how I think about it (and it makes sense).

In order to move, we need fuel. Our body uses two fuels: fat and glucose (sugar).

Fat is very efficient, it gets more km’s from the tank but it’s pretty low-powered. Glucose is the opposite. It generates a lot of power very quickly, but it’s less efficient. We run out much faster and it generates a lot of waste products so we don’t want to use it for too long.

In this way, we are very similar to a car. Some cars get great fuel mileage. They can hum along at 60km/hr with ease. Other cars sound like they’re working over-time just to keep up with traffic.

Typically when you’re working at a lower intensity you’ll be using more fat as fuel. When the intensity dials up you switch to the faster, more high-powered fuel source; glucose. We can turn glucose into fuel in lots of different ways, but when we’re trying to burn fat for energy this only occurs in the mitochondria.

Think of your mitochondria like your cars engine. This is where your energy (ATP) is produced and the healthier your mitochondria are, the better they are at using fat as a fuel source. The ability to use both these kinds of fuels (fat and glucose) is called “metabolic flexibility”.

Unhealthy mitochondria (engines) ie. in sedentary or inactive people, will very quickly switch over from using fat as a fuel source to the more high-powered, less efficient glucose system. Once we start using this system we start to accumulate lactic acid and you’ll get that “burning sensation” and the effort becomes unsustainable. This is metabolic inflexibility.

This is an unfair and unjust fact, but metabolically “unhealthy” people are often unable to access their fat stores and rely exclusively on glucose. So the people who need to burn fat the most, the people with the most of it, can’t use it for energy, while the lean, well-trained professional athletes are able to do so easily because they have metabolic flexibility (and healthy mitochondria).

Part 2: The Benefits Of Zone 2 Training

TL;DR – Building a base-level of fitness helps in all aspects of life. Having healthy mitochondria helps us keep fat accumulation under control and prevents development of chronic diseases ie. diabetes & cardiovascular disease.

We know the accumulation of excess fat stores drives conditions such as diabetes and cardiovascular disease. Healthy mitochondria (driven by Zone 2 training) helps us keep this fat accumulation under control. When exercising at this slower pace, most of the work is being done by our slow-twitch muscles fibres. These muscles are extremely full of mitochondria.

Mitochondria health becomes especially important as we grow older, because one of the most significant hallmarks of ageing is the decline in number and quality of our mitochondria. But this doesn’t have to be so. When we do aerobic exercise, it stimulates the creation of new and more efficient mitochondria!

Zone 2 training builds a base of endurance for anything you’re doing in life, whether it’s riding your bike in a 100km race or playing with your kids, or grandkids. The second reason, it plays a crucial role in preventing chronic disease by improving the health and efficiency of your mitochondria.

It significantly improves your cardiovascular health. Your heart gets better at pumping blood, and your muscles become more adept at utilising oxygen. It’s like upgrading your body’s software to perform more efficiently at everyday tasks. And the best part? It’s sustainable. You’re less likely to face burnout, keeping your mental health in check and making exercise an enjoyable part of your life.

A person doing Zone 2 training is improving their mitochondria with every run, swim or bike ride. But if you don’t use them, you lose them.

Part 3: Identifying Your Zone 2

TL;DR – You’re in Zone 2 if you can have a conversation, but completing full sentences is tough. If you prefer numbers, this typically equates to working at a steady pace of ~60-80% of your maxHR.

Dr. Peter Attia describes Zone 2 training in his book “Outlive – The Science & Art of Longevity” as the following: ”Zone 2 is more or less the same in all training models: going at a speed slow enough that one can maintain a conversation but fast enough that the conversation might be a little strained. It translates to aerobic activity somewhere between easy – moderate.”

Method 1: Using the number

You can calculate your Zone 2 heart rate by first determining your maximum heart rate (the general formula is 220 minus your age) and then working out 60-80% of that number. Technology can lend a hand here, with various apps and gadgets designed to monitor your heart rate and ensure you’re in the right zone.

Method 1: The Talk Test

If you’re at the top of Zone 2, you should be able to talk but not particularly interested in holding a conversation. If you can’t speak in complete sentences at all, you’re likely in Zone 3. Which means you’re going too hard. But, if you can comfortably converse, you’re likely in Zone 1 (which is too easy).

Part 4: Creating Your Zone 2 Training Plan

TL;DR – Zone 2 training is easy to do. It’s about consistency not about hitting PB’s. Start with 2 x 30min sessions each week if you’re new to training and gradually build up to ~3hrs per week for maximum benefits. 

The beauty of Zone 2 training is its flexibility. You can easily incorporate it into your existing routine by dedicating specific days to it, or using it as a warm-up or cool-down. The key is consistency. The other benefit is that it’s very easy to do, even for sedentary people.

For some people, a fast walk might get them into Zone 2. If you’re slightly fitter, perhaps this means walking uphill. There are lots of ways you can do it: stationary bike, walk, jog, swim etc. The key is finding an activity that you enjoy, fits your lifestyle and is comfortable enough that you can work at a steady pace whilst talking in full sentences (but only just).

How much Zone 2 training you need depends on who you are. If you’re starting from nothing, you’ll get huge benefits from just 2 x 30min sessions per week to start with. Based on the science, it seems that in order to get full benefits you need to work your way up to ~3hrs per week of Zone 2 training (once you get past the initial struggle of getting started).

People who are training for endurance events will obviously need more than this.

Measuring your progress can be simple! It’s not about the numbers, it’s about consistency. But over time, you’ll notice you might walk, swim or ride further in the same time-frame. Remember: the goal is to stay in Zone 2 for this style of training, this isn’t about PB’s!

Part 5: Tips To Maximise Your Zone 2 Training

TL;DR – REMEMBER: The point of Zone 2 is to remain in Zone 2. Don’t get caught up in times, distances, PB’s etc. Save that for another session or competition day. Use this time to listen to podcasts or audiobooks for extra brain benefits.

While Zone 2 training might sound like a breeze, there are a few pitfalls to avoid. First, don’t overdo it. Yes, it’s moderate exercise, but recovery is still essential. Also, ensure you’re actually staying in Zone 2. Too easy, and you won’t reap the benefits; too hard, and you’re not doing Zone 2 training anymore.

PRO TIP: Remember if you’re “feeling the burn”, you’ve swapped to the less-efficient glucose system. Dial it back a little.

Zone 2 training can seem pretty boring on its own. I use the time to listen to podcasts, audiobooks or just have some time away from technology and clear my head and get clarity of thoughts. A little side-benefit of Zone 2 training is that when paired with learning (due to the increased blood flow and BDNF to the brain) not only does it help with cognition, it’s an important component of Alzheimer’s prevention.

NOTE: BDNF = brain-derived neurotrophic factor. It’s basically like fertiliser for your brain. It boosts neuroplasticity, helps your brain cells grow, stay healthy and communicate with each other. It’s especially important for learning and memory.

The Wrap Up:

TL;DR – When it comes to health, sometimes slow & steady does win the race.

Zone 2 training may not have the glamour of high-intensity interval training or the bragging rights of running a marathon. But it’s an easy, incredibly effective and sustainable way to improve your cardiovascular health, endurance and overall well-being. It’s about making exercise enjoyable and manageable.

A nice reminder that sometimes, in the journey towards good health, slow and steady does win the race.

So why not give Zone 2 training a go? Use that FitBit, Apple Watch, Whoop, Garmin etc and head off for a walk. Or grab a friend and turn it social (of course the conversation will be a little strained, but you can monitor each other).

If you need help navigating this process and want to work alongside a team of Health Pro’s to help you find a sustainable health routine then you can always reach out to us. We offer free 30min consults with our Founder Dr Matt Corbin to grab a second opinion, discuss our program or suggest any alternatives that might be more suitable for you.

Now stop reading and get out there. Sweat less. Find your Zone 2. Improve your health. Live better, longer.

Learn Something? Join Our Newsletter For More