How To Use Zone 2 Training for Better Health and Metabolic Flexibility

Jul 9, 2023

 by Stephen Conca

Zone 2 Training for Better Health and Metabolic Flexibility 


It’s time we stop talking about burning calories as one of the primary benefits of exercise.


In the last post, we discussed taking a more tactical approach to our health and fitness.  As we segway into how to train for better metabolic health let's give you a reference on how to take this tactical approach with an example of car accidents. 


A motor vehicle death occurs every 12 minutes in the U.S.  Is it possible to avoid this?  The tactic is simple, wear a seat belt, no electronics while driving, no alcohol or drugs, and don’t speed.  You need to recognize the danger points to develop good tactics.  Research shows intersections, not highways, contribute to more fatalities. The most common fatality is being hit on the driver's side by someone running a red light at high speed. At intersections, we have choices about when to go, and where to look.  This gives us a tactic to specifically look left twice.  This gives our tactical approach leverage.  A minor tactical decision can go a long way.

The same holds true with our health.  We want to get specific about our approach to exercise. We can use data, research, and intuition to see what’s working, and what’s not and make adjustments along the way. 


Just as we have accepted the hazards of the car and learned to navigate the dangers, the same holds true for our health. We must learn to navigate the hazards in our environment, and in our food supply to mitigate the risks to our health and improve our health span.


Let’s begin to switch our mindset about what kind of fuel we use while exercising.  

How we use glucose and fatty acids is critical to overall metabolic health. 


Aerobic exercise, if done in a very specific way, improves the body's ability to utilize glucose and fat as fuel.  This type of training has been shunned by some fitness enthusiasts due to the time it takes out of a busy schedule. However, Zone 2 training has significant health and performance benefits that are difficult or impossible to get from any other form of conditioning.  


Your cardiovascular training can fit into 6 different zones, but we’re going to focus on Zone 2.  Typically, zone 1 is a walk in the park, and zone 5-7, depending on the model you are looking at, is an ll out sprint. In Zone 2 your heart rate sits at 60-70% of your maximum heart rate (MHR) for an extended time, ideally for at least 20 minutes, but sometimes 45 minutes and beyond.  You can do Zone 2 training with any repetitive activity, so long as your heart rate stays in the 60-70% range.


Zone 2 is relatively the same for every model, where you are going at a speed that you can maintain a conversation, but that conversation might be a little strained. So it’s somewhere between easy and moderate. 


Some health benefits Zone 2 training:


  • Improved metabolic flexibility - the ability of the mitochondria to convert glucose and fatty acids into fuel.  Fatty acids are only used as fuel in the mitochondria of the cell
  • Mitochondria efficiency goes up then your endurance goes up, and then your ability to burn more fat as fuel goes up. 
  • Builds a base of endurance for everything we do in life from improving daily physical stamina and energy to doing anything from shopping to yard work, to sex, to walking your dog to playing with your grandkids.  
  • Promotes type 1 or “slow twitch”  muscle fibers which are extremely dense with mitochondria.
  • Reduces the risk of most chronic diseases


The mitochondria in people with type 2 diabetes get hit really hard as well as people with metabolic syndrome and obesity.  They have much higher resting lactate levels which tells us that they are relying mostly on glucose for their energy.  They just can’t access fat stores.  This is a tough place to be because those that need to burn the most fat for energy are unable to access it.  Starting at a very low level of exercise for these people is critical in helping to rebalance the body. 


Bad News

Why is mitochondria health so important? As we age one of the significant declines is the number and quality of the mitochondria we have. 


Good News

With Zone 2 Aerobic training we can stimulate more mitochondria while eliminating old and dysfunctional ones through a process called mitophagy.  Very similar to autophagy that we covered during our conversations on the benefits of a functional medicine detox. 

Another huge benefit of zone 2 training is it greatly increases the body's ability to maintain healthy blood glucose levels. Chronic blood glucose levels have damaging health effects ranging from brain and kidney malfunctions to erectile dysfunction in men. 


Zone 2 training is very easy to do 

Even if you have been sedentary, a brisk walk could get you into zone 2. If you’re in a little better shape walking up a hill might be necessary.  There is no one BEST activity. Jogging, cycling, swimming, rowing, elliptical…..anything that you enjoy that allows you to maintain a HR range of 60-70%  for an extended period of time. 


Since I started cycling I have become so addicted to the benefits im feeling with Zone 2 training!


How many times per week?  The recommended amount is 120 minutes per week.  You can break that down to be (2)2x30 min, 4x30 min, or even 6x20 min sessions/week.  


Is it possible to do too much?  There is no upper limit to the training volume.  As long as the exercise modalities that you use do not hurt your joints. Doing different exercises, biking, rowing, running, walking, etc. will mitigate your risk of coming down with an overuse injury. 


What are the signs that you need to do more of this Zone 2 Training?  An average resting heart rate (taken first thing in the morning for a month) that’s >60-63 bpm (beats per minute), is a clear sign that you need to do more.


Also, look at your current mitochondrial function as a sign of low Zone 2 capacity.  Some signs of sub-optimal mitochondria include chronic pain, low energy, mental health struggles, brain fog, sleep, and memory issues.  But just because you may have 1 or 2 symptoms, doesn’t automatically mean sub-optimal mitochondria, but it’s important to not ignore any symptoms.


To calculate your heart rate, take 220 and - your age.  For a 30-year-old, that would be 190. From there, to get to 60 & 70% you would calculate (190 x.60) and (190 x.70), which would be 114-133 bpm.


Start your Zone 2 Training with at least 20 minutes per session, a few times per week.  Gradually increase your time and work up to 45-90 minutes.  A way to measure if you’re in the correct zone (if you don’t have a heart rate monitor) is that you should be able to carry on a conversation without being out of breath.


Here’s how to track your progress.  You can measure your watts during your training session.  The best way to measure watts is on a stationary bike. 


Take your average wattage for a session and divide it by your weight to get your watts/kg.

A reasonably fit person should be slightly more than 2 watts/kg.  A very fit person will be about 3 watts/kg and an elite cyclist will be at 4 and up. 


Think of zone 2 training as pouring the foundation for your health. Just as you would pour the foundation for your house, not many will see it, but it will support everything else we do to the house.  Your house and your health need a solid foundation.