Zone 2 training might not seem like the most exciting way to develop your aerobic endurance.
Plodding your way through a zone 2 cardio workout without breathing heavy doesn’t sound as hardcore as blasting a high intensity Tabata session and finishing in a pool of your own blood, sweat and tears…
But as the old parable goes:
“The wise man built his house upon the rock”.
One of my underlying goals here at Hero Movement is to explore and share training methods and habits that are sustainable.
Alongside mobility training and other restorative practices, that’s where long duration, low intensity aerobic work – aka zone 2 training – comes into play.
This doesn’t mean I’m anti high-intensity training – it definitely has its place.
But in this article, I want to highlight the equally important role of slowing down with zone 2 cardio.
Not just in promoting health and longevity, but in establishing a strong underlying aerobic base for athletic performance.
Whether you’re an aspiring triathlete or a weekend warrior, hopefully you’ll find something useful below that you can apply to your own movement practice.
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Before we get stuck into the nitty gritty of zone 2 training, let’s go over some basic definitions:
To get our bodies moving, we need to transform the energy found in our food and stored in our body into a usable form, and we do this using three energy systems:
These energy systems contribute varying amounts towards re-synthesising the compound Adenosine Triphosphate (ATP), which we can think of as the ‘energy currency of our body’.
ATP is essentially the only source of energy our body can use for work.
The main energy system we utilise depends on the intensity, type, and duration of exercise being performed, as well as the fuel sources available and the fitness levels of the individual.
Refer to my expertly drawn graph below for a visual representation:
As you can see from another expertly designed diagram below, exercise intensity can be split into distinct training zones based on a percentage of our maximum heart rate:
One of the BIG problems with the way many training programs are set out:
We’re big on the strength training, HIIT work, and weekend 5ks, but we forget about all the low-intensity work in-between.
So that equates to a lot of zone 0 (sitting at work, in the car, and in front of the TV) and small amounts of zones 3-6 work (lifting weights, running, HIIT training), but not a lot in zones 1 and 2.
This is sometimes referred to as the Grey Zone of no improvement (more on this later).
There are many people much smarter than me who feel that zone 2 work underpins and improves the efficiency of higher intensity work.
By skipping it, it seems you’re cheating yourself out of a myriad of potential benefits…
When you start to incorporate it, not only do you become a more efficient endurance athlete, but it can also mean you’re able to perform at a faster pace without placing as much stress on your body.
As well as upping our low-level physical activity throughout the day, we can also train to make specific adaptations in zone 2.
The goal with zone 2 training is to exercise at a pace that allows you to sustain your heart rate just below the aerobic threshold for a prolonged time period (typically 30 minutes+).
Dr. Phil Maffetone is widely regarded as the one of the leaders in the Z2 running movement – I highly recommend checking out his website here.
He was a big proponent of low intensity training, whole food nutrition, and proper recovery protocols way back in the 80’s, and coached triathlete Mark Allen to 6 Ironman World Championship victories.
Unfortunately, despite having success with some of the top athletes in the world, many of Maffetone’s genius training methods didn’t take off in the mainstream.
In a world where ‘lifehacks’ are king and the ‘go hard or go home’ mentality is celebrated, it’s easy to see how zone 2 isn’t as easy to sell as HIIT. The slow and steady approach is never as appealing as the apparent quick fix…
Nonetheless, the science is there, the results speak for themselves, and his training methods have stood the test of time.
If you want to engage in some focused zone 2 heart rate training, you ideally need to figure out your starting point.
The number we need is the upper limit of your zone 2 – your aerobic threshold, or sometimes referred to as your MAF (Maximum Aerobic Function) heart rate.
If you have the time and money and want a real accurate measurement, you can go to a fancy lab and take a blood lactate test.
They’ll hook you up to a heart rate monitor take samples of your blood as you exercise with increasing intensity until failure.
Expensive and not fun…
The easier method is do some basic calculations to get an approximate value. There are various ways one can calculate their zone 2. I personally like using the ‘Maffetone Method’, developed by the legend himself, also referred to as the 180-age formula.
Maffetone observed in his athletes that this was the point at which their form began to break down, as they made the transition from being predominantly aerobic, to using the anaerobic energy systems.
The length of a zone 2 training session will vary depending on your current fitness levels and your goals, but below I’ve listed a framework that’ll help you get started.
We’ll use the example of a 30 year old athlete that’s had fairly consistent training and no health issues.
Using the Maffetone Method, their upper limit for zone 2 would be around 180 – 30 = 150 bpm.
As someone who used to embrace the ‘go hard or go home’ mentality, it was difficult for me at first to comprehend finishing a session without even breaking a sweat.
In the early stages (particularly if you encounter hills) you’ll no doubt find you have to slow down to a walk to stay in that heart rate zone.
It can be frustrating at first, but this is where patience and perseverance comes into play. Sometimes we have to check our ego, slow down, and learn to walk before we run…
Over time, with consistent training you’ll find that you can move at a faster pace while staying in your zone 2. You’re effectively becoming a more efficient, fat-burning machine.
One of the best ways to track your progress with zone 2 training is to perform the MAF Test every 1-2 months time.
Some of the biggest adaptations from aerobic work are cardiovascular in nature:
Aerobic training also causes metabolic adaptations:
Other adaptations include favourable changes in body composition, increased endurance performance, and psychological benefits.
There are a number of misconceptions regarding zone 2 training that are worth mentioning:
Misconception 1: Aerobic training is not beneficial for high intensity sports and events.
Misconception 2: Aerobic training causes you to lose strength + speed.
Misconception 3: Tabata style HIIT training has been shown to be superior to Z2 steady-state.
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Generally speaking, anaerobic training sessions are shorter and more intense than aerobic sessions, and you’ll spend most of your working time above the aerobic threshold, with periods of rest in between periods of work.
The predominant adaptations that can be seen with high intensity, anaerobic training include:
As we can see, although many of these adaptations are beneficial, they’re quite different in nature to those seen with low intensity aerobic training.
Training anaerobically may increase your speed and ability to tolerate higher intensities for longer periods of time, but training aerobically increases the efficiency of your cardiovascular and respiratory systems, allowing you to work at a higher intensity without having to resort to using the anaerobic system as much.
This preserves your glycogen fuel source, and potentially puts lets stress on the central nervous system – which from my experience takes more of a battering with prolonged anaerobic training.
A great analogy I heard Simon Ward share on his podcast was this:
Aerobic zone 2 training is like raising the water level so a boat is higher up, whereas anaerobic training is like using a crane to lift the boat up instead.
When the water level rises, the boat naturally sits higher without much effort, whereas a crane requires a high energy output to maintain that same elevation.
Here’s yet another one of my expertly designed diagrams to demonstrate this:
Although anaerobic training is definitely a great tool, using it incorrectly or introducing it too soon into an exercise program can potentially do more harm than good.
Excessive training intensity and abrupt changes in training volume may increase the risk for injury to bones, joints and muscles.
Obviously low-intensity aerobic training also brings with it some risks:
If your form is poor, those reps add up over a long run and can lead to overuse injuries. But the same can be said for high intensity work (and the risk of injury may be higher due to increased force production).
If not managed properly, excessive anaerobic training may encourage the body towards an acidic state, potentially due to the excess build up of lactic acid. This acidic environment is associated with inflammation and an increased risk of many chronic diseases.
Overtraining can also become an issue, with associated alterations in neuroendocrine and immune functions.
This can be a slippery slope, leading to chronic fatigue, poor exercise performance, frequent infections, and a general loss of interest in training.
One of the most common issues we see in the health and fitness space is this:
People go too hard on their easy days, and too easy on their hard days.
They’re forever training in the ‘grey zone’ of no improvement.
The training intensity is not low enough to get the benefits of zone 2 cardio training, but not hard enough to induce significant anaerobic adaptations.
Always training this way leaves you with one speed, and takes your body to a state where it’s never quite rested enough to go hard when you really need it too.
I’ve definitely experienced this myself.
Years of combining high intensity and grey zone training with inadequate rest has no doubt contributed towards some of the health issues and injuries I’ve faced.
So along with focussing on my core strength and flexibility, I’m now exploring the more laid back aerobic training approach to build my body back up.
For the average person looking to be a bit fitter and perhaps lose some weight, I like using the 80:20 approach for endurance training after an initial base-building period of 3-6 months.
So around 80% of your time would be spent doing Z2 training, and the remaining 20% would be higher intensity work.
For athletes that compete at a higher intensity, that ration may look more like 70:30 or 60:40, but it would still be built upon a solid aerobic base.
My preferred way to build an aerobic base would be to go back to basics and forgo any high-intensity style training (aside from strength training), working solely on Z2 work for 3-6 months.
By doing this, we become much more efficient athletes, and can work at a higher pace while placing less strain on the body.
As improvements in Z2 begin to slow, we would then introduce occasional interval style training 1-2 times per week. Faartlek, Tabata – whatever you enjoy, or whatever’s most relevant to your training goals.
So to use my current training schedule as an example:
I’m not saying this is the ideal way to train for everyone, but the below as a general framework tends to work pretty well for me at the moment to enjoy a fairly well-balanced movement skillset.
Strength + Mobility
Z2 Run & BJJ
Rest & Walk
Strength & BJJ
Climb / Surf Paddle / Walk
Depends on recovery
For the longest time in the world of endurance sports, it was believed that athletes needed to fill up on carbohydrates in order to perform at their best.
But that’s not necessarily the case.
This is something Maffetone was talking about in the 80’s has since seen a resurgence.
We know that fat is the preferred fuel source when we’re working aerobically. So if we’re performing most of our training at an aerobic pace, do we really need to be filling up on a giant bowl of pasta prior to a long run, or shoving sugary energy gels down our necks every 15 minutes on a bike ride?
Instead, we might find that if we reduce the sugar, increase our fat intake and prioritize whole foods, we’ll feel and perform much better.
I’m not going to tell you what to eat – it’s about finding your personal sweet spot.
For some that might be fairly low carb or full blow keto. Others get on well with with a more balanced macro profile, or even adopting the carb backloading approach.
The main takeaway is to test things out for yourself and find what works best for you.
High intensity training is alluring – allowing you to feel the burn and get work done in a shorter timeframe.
But the truth is, working harder doesn’t necessarily always produce greater or faster results, and can potentially cause more harm than good.
You can’t really do any significant damage by training too easily, but you can by training just a little too hard.
For me, it makes sense that to achieve optimum health and to fulfil your athletic potential, it is safer to lay the foundations with a strong aerobic base, then build upon it with small amounts of high intensity work.
Build the base of your pyramid as wide and solid as you can, in order for the top to be as strong as possible.
I may have botched that quote a bit, but I think that sums it up quite nicely.
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