How hard should you train to improve your VO2 max?
- Dr. Kenji Kaye, MD
- Jul 23
- 3 min read
Updated: Sep 17
Starting point
Every patient’s situation is unique. What level is your fitness at currently? What was your historical peak fitness level? How long did you sustain this? What kind of injuries are you dealing with? These are just a few of the questions I like to review with patients before embarking on a protocol to improve a patient’s cardiorespiratory fitness.
Laying down a strong foundation to build your cardiorespiratory fitness on is the first place we start. Most exercise protocols focus on this foundation by incorporating what is known as Zone 2 training. Zone 2 can be explained in a few different ways. The most common was Zone 2 is utilized is by determining your max heart rate with the equation 220-Age to determine your “maximum heart rate”. Obviously, there is some variability with this equation but it gives us a rough place to start.
Zone 2 refers to the second zone, out of 5, and is roughly 60-70% of your max heart rate. So if you are 40 years old (220-40=180 and 60% of 180bpm is 108bpm). Zone 5 would be max effort or near your max heart rate. Exercise physiologists often get further into the weeds about the definition of Zone 2 and which type of muscle fibers are activated in which zones but for our purposes just targeting heart rate can give us a place to start. Another way Zone 2 training is taught is through something called “relative perceived effort” or RPE. Zone 2 is often described as a level of exercise you can sustain while having a conversation with a partner. For example, if you are doing a light jog or cycling with a companion are you able to sustain a conversation without changing your speed or stride? If so we also can consider this zone 2 training. Dr. Peter Attia (author of Outlive) tends to utilize point of care lactate testing to determine if someone is in zone 2 but this requires finger sticks and fancy machines which most patients generally not too keen on when exercising.
What are the benefits of Zone 2 training to improve your VO2 max?
There are many benefits to zone 2 training including burning more fat, building your aerobic base, boosts your mitochondrial health, and is not as stress inducing to your system. For the purposes of this article we will focus on the aerobic building benefits of Zone 2 training. The analogy often used is to think of your cardiorespiratory fitness as a pyramid. With the base of the pyramid consisting of Zone 2 training to widen the base and the peak of the pyramid is your VO2 max. To increase the height of the pyramid we need to make sure the base of the pyramid is nice and wide (strong) to support a higher and higher peak. Typically it is advised to spend about 80% of your cardiovascular training in a zone 2 and 20% of your training specifically improving your VO2 max (the peak of the pyramid). The gold standard protocol for this type of zone 5/VO2 max training is the Norwegian 4x4. This is a level of exertion that you can barely do 4 minutes of and then you need 4 minutes of rest/recovery before you can do that again. Then you do this 4 times.
How do we do zone 2 training and for how long?
We should first look at where we want to end up and then figure out what we need to do to get there. Ideally, we should be aiming for 3 hours a week broken up into three 60-minute sessions or 4x 45-minute sessions of Zone 2. Obviously if a patient is starting out more on the sedentary end of the scale we will need to build up to this over the course of multiple months to a year. Find your comfortable talking pace and start there. It does not matter if you are running, cycling, using the Peloton, Stairmaster, etc. You should be able to speak in full sentences, but with a slightly elevated heart rate and noticeable breathing. Are you ready to start your own health journey?
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