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"The Science Behind Zone 2 Training: Why it Matters for Health and Longevity"

We all know doing “cardio” is essential for our health and longevity.  That said, did you know that after 40, our Vo2 Max declines on average 10% per decade? This may not sound significant, but if your goal is to do some of the modest activities you can do now, such as hiking in the woods in your 80’s or beyond, it may not be possible based on our body's natural rate of decline . That is, unless you are currently dedicating time to cardiovascular exercise to improve and maintain your cardiovascular health.  With all this said, you may be thinking: What the heck is zone 2 training and why do I need to do it? I go for walks, is that enough? How much cardio do I need to do? How often? How do I get started? What’s the best type of cardio? All important questions, so keep reading to find out. 

Side view of a fit women running on treadmill

Full disclosure, this post is highly influenced by Dr.Peter Attia’s work and the recommendations he makes in his podcasts and his book “Outlive”.  It’s a must read if you care about longevity, or more importantly as he states it, extending your “health span”. 

To paraphrase from Dr. Attia, when it comes to thinking about the performance of our cardiovascular system or Vo2 Max, its best to visualize the shape of a triangle.  Basically, the more efficient your cardiovascular system is, the bigger your "triangle" is.  When it comes to improving your “triangle”, the base or breadth is built/improved by doing steady state zone 2 training.  The height, or the peak is increased from higher intensity 4 or 5 training zones.   

Improving your Vo2 Max or “triangle” needs to be strategic in the sense that each zone has different effects on your physiology and therefore different benefits to your health and performance.  Each zone has a minimum effective dose.  

“Zone 2”, also referred to as “steady state” cardio, should make up 80% of the time you alot for your cardiovascular training (the base).  This is both a pro and a con, as it’s not that “hard” in relation to perceived exertion, but it takes a fair amount of time.  Ideally working up to a total of 3-4 hours a week in 30-60+ minute blocks.

“Zone 5 or HR Max training” makes up the remaining 20% of your training. It’s definitely “pushing it”, and is NOT comfortable, therefore should be worked up to slowly over time with as dose of 1-2 bouts a week.  (I'll write more detail on this in Part 2 of this article) 

So how do I know if I’m in Zone 2 when I do cardio?

There are several ways you can gauge whether you are in Zone 2.

  • You can talk but would prefer not to

  • You can do the session with just nasal breathing

  • You are between 70-80% of target HR zone based on age (more or less). Here's a quick calculator

  • There should NOT be lactate accumulation (if legs are burning with lactic acid you are going too hard) 

  • Zone 2 training typically falls within the range of 4 to 6 on the perceived exertion scale of 1 to 10. This means Zone 2 training should be perceived as moderate—neither too light nor too hard.

Why do I need to do Zone 2 Training

  1. Improved Aerobic Capacity: Zone 2 training enhances the body's ability to utilize oxygen efficiently, leading to increased aerobic capacity. This means your muscles become better at using oxygen to produce energy, allowing you to perform activities for longer durations without fatigue.

  2. Enhanced Fat Utilization: Training in Zone 2 helps the body become more efficient at burning fat for fuel. This is beneficial for endurance athletes as it conserves glycogen stores, delaying the onset of fatigue during prolonged exercise.

  3. Increased Mitochondrial Density: Mitochondria are the powerhouses of cells, responsible for energy production. Zone 2 training can increase the number and efficiency of mitochondria in muscle cells, improving overall energy production.

  4. Improved Cardiac Function: Regular training in this zone strengthens the heart muscles, enhancing its ability to pump blood more efficiently. This leads to a lower resting heart rate, increased stroke volume (amount of blood pumped per beat), and improved overall cardiovascular health.

  5. Muscular Adaptations: Zone 2 training contributes to better capillary density in muscles, improving blood flow and oxygen delivery to working muscles. This can enhance endurance and performance during sustained exercise.

  6. Reduced Risk of Overtraining: Zone 2 training allows for sufficient recovery between higher intensity workouts, helping prevent overtraining and reducing the risk of injuries.

  7. Better Metabolic Efficiency: Regularly training in Zone 2 can improve the body's ability to regulate and utilize energy more efficiently, contributing to better overall metabolic health.

  8. Mental Health Benefits: Zone 2 training and other forms of exercise are linked to improved mood, reduced stress, and better sleep—all of which indirectly contribute to brain health and cognitive function.

  9. Neuroprotective Effects: Exercise is believed to stimulate the release of chemicals in the brain that promote the growth of new brain cells and connections. This could potentially protect against neurodegenerative diseases like Alzheimer's.

These points are interesting but why do we REALLY need to train our cardiovascular system? Enter Dr. Attia's "Centurian Olympics", the REAL WHY.

Dr. Attia presents a list of 50 physical tasks to his patients and asks them to choose which one's they want to be able to perform in their later decades. A few examples from his list include: hike 1.5 miles on a hilly trail, pick up a young child from the floor, climb 4 flights of stairs in 3 minutes, carry two five-pound bags of groceries for 5 blocks. The point of this exercise is to help develop an exercise strategy specific to the person's lifestyle aspirations in their later decades . Dr. Attia refers to this as training for the "Centurian Olympics". This pro-active approach is what Dr. Attia also refers to as Medicine 3.0.

They key is PRO- Active. But what if we don't have an exercise routine?

Well this is where basic math and reality enter the equation unfortunately. The following examples are paraphrased from Dr. Attia's book "Outlive".

Strength declines between 8-17% per decade. If your goal is to lift a young child weighing 25-30 pounds from the floor, this is the equivalent of doing a goblet squat with that same amount of weight. Following the math, let's say you are 40 years old now, you would need to be able to goblet squat at least 55 pounds now when you account for the bodies natural decline in strength.

VO2 Max declines about 10% per decade and up to 15% per decade after 50. If hiking 1.5 miles on a hilly trail comfortbly is one of your later decade goals, you will need a VO2 Max of about 30 to do so. Lets refer to the math again. The average Vo2 Max of a 40 year old female ranges from 27-31......I think you can see where this is going.

The central point Dr. Attia keeps making is: if you want to be exceptional in your later decades, you can't be average now.

I go for walks, is that enough?

In short, probably not if you are an average gym goer (which I think many reading this are). Like many fitness questions it depends on the individual and such variables as age, fitness level, body weight, walking pace, elevation, duration.  However, consider this scenario: many people strive to achieve 10k steps a day (which is great). The issue is the steps are most likely done in a segmented way at a leisurely pace.  If all walking is done in this manner, it won’t elevate your heart rate high enough, or long enough to meet zone 2 criteria.  This is not a dis on walking or getting movement in throughout the day, its just meant to create clarity if your goal is to improve your cardiovascular system (triangle). If you choose walking for your cardio, it needs to be purposeful, long enough, and intense enough to qualify as zone 2 (I personally can’t walk fast enough to get into zone 2).  Side note: walking indoors on treadmill is much easier to get precise with the appropriate intensity you want by controlling the elevation/speed. Also, using a weighted vest outdoors is another option if you would rather not walk like a speed walker in the Olympics. 

What if I’m just a beginner? How in the flying f*ck am I supposed to do 3-4 hours a week?

Don’t! Start with walking or any other zone 1 activities, consult a doctor and slowly build up over time.  Congrats on reading this article and taking action to improve your health! 

What’s the best type of cardio activity to do?

There is no “best”.  The best activity is the one you will do consistently.  So as long as you are able to maintain the target HR parameters and its pain free on the joints then go for it.  I would also recommend experimenting with different machines and activities. You never know what you end up preferring. I personally like using the spin bike. 

Now that the basic questions are addressed, what about the common barriers we all experience? (myself included)

“It’s too boring”

Yes, this was one of my excuses.  Until I reframed it as an opportunity to multi-task. Because zone 2 training, by definition of perceived exertion is not very hard, am able to keep my mind busy with other things.  Most of the time I’m listening to an interesting podcast, audiobook, or educational YouTube video.  Other times I’ll call a friend to catch up.  Sometimes I’ll answer emails or do my scheduling. Another one of my strategies to reduce the monoteny is by playing “cardio musical chairs”. Let’s say my goal is 45 minutes of cardio, I’ll mix and match different cardio machines for 15 minutes each. For example I’ll start off running on treadmill, then switch to bike, then finish on elliptical. I find the variety makes time go by a bit faster.  Some of my clients try to incentivize themselves by saving their guilty pleasure Netflix shows for cardio time.  The key is to only watching the show during cardio sessions. 


“It feels too hard”  

If this is the case, most likely you are going above zone 2.  This is quite common if you find yourself in a scenario similar to the following.  Let’s say someone has a 5k run route they typically do and they try to get progressively a little faster at it each time.  This is totally logical. But not if your goal is to stay in zone 2.  As you get in better shape, you are able to push harder and run a little faster- this is why it’s tiring or feels hard, because it probably is.  There is nothing inherently wrong with this (as doing something is always better than not), however you are not achieving the specific physiological benefits that Zone 2 training (nor zone 5) offer.  It’s not intuitive but there is more value and efficiency in training in the polar ends of your HR zones seperately (zone 2 and 5) then grinding through cardio sessions in the middle of zones 3 and 4. 

“I don’t have enough time” 

Yes it does take a significant portion of time.  Other than that, the only thing I will say is that it’s rarely truly a time issue, it’s almost always a priority issue. People (myself included) always find time for the things they really want to do, the issue is their priorities are often assed backwards. Think: average daily social media scroll time, Netflix time, watching news, video games etc. If time really is a factor, consider the multi-tasking method I mentioned above and try to apply it to your own life.

Hopefully this article presented a solid case for a pro active approach to fitness and the importance of zone 2 training. It should also be noted that Zone 2 is only part of balanced fitness plan that needs to include strength training, mobility/stability, HR max training. Although it may seem discouraging the amount of times I referenced our bodies rate of natural physical decline (especially if your fitness routine is not where you want it to be), but the good new is that all elements of fitness can be improved at any age, with the right training methods and strategy. This is why hiring an experienced coach to meet you where you are at, and help get the most return from the time you put in is a powerful investment.

Please comment and share this article if you found it useful and feel free to reach out with any questions.

If you, or someone you know, needs help with a sleep, nutrition or fitness routine, please reach out. Either online or in the gym, I specialize in helping busy professionals over 40 get fit without burning out. My personal training studio services downtown Toronto and is just steps away from the UP Union to Pearson Express Station.


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Klaus Anselm
Klaus Anselm

Great article! Thanks for putting this together, it helps!!


Thanks Klaus..Happy Holidays !

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