VO2max Explained
There’s a lot of fancy terms that tend to get thrown around in the fitness world. VO2max is one of those terms, and it’s not the easiest term to define at a first glance.
However, whether you’re an athlete or someone who just wants to live & healthy life, it’s worth having a basic understanding of what your VO2max is.
As such, the aim of this article is to explain what your VO2max is, why it is important, how to measure it, and how to improve it.
What is your VO2max?
Put simply, your VO2max is the maximal (max) volume (V) of oxygen (O2) that your body can take up and utilize for exercise. Whenever we are performing aerobic exercise, the limiting factor is how much oxygen can be taken up and used by the working muscles. If your body can take up and use more oxygen, then it will be able to perform more work or sustain work for longer periods of time.
The term “aerobic” means requiring oxygen. Its counterpart, anaerobic, means something does not require oxygen. For instance, many microbes at the bottom of the ocean are ‘anaerobes’ meaning they are single-celled organisms that don’t need oxygen to live. Within our bodies, we have two energy pathways that are anaerobic and one that is aerobic.
For a greater breakdown of your body’s energy systems, click here
VO2max is measured in ml/kg/min. That is, milliliters of oxygen consumed per kilogram of body mass per minute. In these terms, aerobic capacity can be easily compared across many different body types.
There are multiple factors that affect your body’s ability to deliver oxygen to the working muscles, and ultimately your body’s VO2max. These include:
The cardiac output of your heart
The capillary density of your muscles
The mitochondrial density of your muscles
Your body’s ability to use fat for fuel
Cardiac output
The primary means in which VO2max improves is through increases in cardiac output.
Cardiac output (CO) is a measure of how much blood your heart is able to pump through circulation.
Mathematically, it is represented as CO = (Volume of blood ejected from the heart) x (# of heart beats per minute).
Over time, as you perform and adapt to aerobic training, your heart becomes able to pump more blood with every heart beat.
So, at any given heart rate, more blood is being pumped through circulation.
It is for this reason that a noticeable drop in resting heart rate occurs as your cardiovascular fitness improves.
This is important because oxygen is carried through the body by our red blood cells.
So, if we are able to pump more blood, then we are able to pump more oxygen through the body.
Muscle capillary density
Increases in capillary density also occur as a result of aerobic training.
You can think of capillaries as the blood vessels that act as the exit ramps from your main cardiovascular system to your muscles.
Imagine a highway with one exit ramp at a particular location and an identical highway with 4 exit ramps at that location. You can imagine that the highway with 4 exit ramps will have less traffic and cars will flow out more easily.
This same general concept is what occurs as capillaries increase in density in your muscles. There’s less ‘traffic’ and therefore blood and oxygen can get to your muscles more easily.
Mitochondrial density
A third means in which VO2max can improve is through your mitochondria.
You probably know the mitochondria as the powerhouse of the cell.
It is the structure in the cell in which the vast majority of energy is made. All energy produced here is through aerobic processes. As you perform and adapt to aerobic training, these mitochondria increase in size & density within the muscle cells.
Imagine a company had a small factory in which it could produce its products. Imagine that factory instantly doubled in size. It’s likely that this company will be able to produce more products than it was able to previously. That’s essentially what’s happening to your mitochondria.
As these mitochondria grow in size & density, there is more of the infrastructure available in which oxygen is used in energy production.
Increasing use of fat for fuel
The last way in which VO2max improves occur is through your body’s ability to use fat for fuel.
During exercise, your body can use either fats or carbohydrates as energy.
Fats can provide a lot more energy than carbs, but the process to turn them into energy is slower. Carbohydrates provide less energy, but they can be turned into energy very quickly.
As a person performs & adapts to aerobic training, they begin to produce more of the enzymes that convert fat to energy. This allows such a person to use fat for fuel earlier on in exercise and to a greater magnitude than someone who is not aerobically trained.
One of the main causes of true physical fatigue is when you carbohydrate stores in your muscles & liver get too low. As you are better able to use fat for fuel, your carb stores can last longer; which enhances the work that can be done aerobically.
Why you should care about your VO2max
It should be no secret that exercising and improving your fitness is good for your health. Although that may come as no surprise, you might not realize just how powerful it is.
In fact, improving your fitness is arguably the absolute most important thing you can do for your health in terms of effectiveness, cost, and accessibility.
Improving your VO2max is no exception to the statement just made. Strasser and Burtscher conducted a comprehensive review examining just this. Their research found that improving your VO2max by just 1 ml/kg/min decreases your risk of all-cause mortality by 9%. In fact, they also noted that a trained 70-year old can express the biological age of an untrained 50-year old. That’s pretty neat if you ask me.
It should be noted that improving your VO2max will not extend the genetic potential of human life. Rather, it will help ensure you reach the later portion of your genetic potential and improve your quality of life throughout the process.
Pivoting away from health, an improved VO2max means improved athleticism for many reasons. To start, it is one of the three main indicators of endurance (the other two being lactate threshold and movement economy). Arguably, it is the most important. Only when comparing individuals with identical VO2maxes do the other two indicators become deciding factors.
Even if you are purely a strength or physique athlete (ie weightlifter, powerlifter, bodybuilder, etc), improving your VO2max should be a priority. The better your endurance is, the better your recovery is in between both sets and workouts. The better your recovery, the better your progress over time.
Related: The Health Benefits of Strength Training
How to test your VO2max
There are two easy ways to practically estimate your VO2max.
The first is to run as far as you can in 12 minutes and record how far you get.
The second is to run 1.5 miles as fast as you can. This is best done on a track, and would equate to 6 laps.
If you have access to a track, I would recommend the 1.5 mile run. If you do not have access to a track, I would recommend the 12 minute test alongside some means to measure your distance covered.
Once you have your values for either test, refer to this table. Refer to the table that is appropriate for your sex and age.
It should be noted that VO2max testing is going to suck. After all, you are testing your maximal aerobic capacity. For scores to be accurate, you need to push yourself. Due to how stressful this is to the body, this should not be done too often.
How to improve your VO2max
To fully cover how to improve VO2max would require multiple articles. Developing practical strategies to improve VO2max is one of the things I help clients do in my 1:1 coaching.
For the purposes of this article, I’ll give you the cliff notes.
To start, there are two main variables to cardiovascular training that are important: intensity and duration.
Manipulating these variables should be your primary consideration whenever you’re seeking to set up a cardiovascular program.
A commonly recommended framework that will work for most goals is the following distribution of duration and intensity:
75% of your work @ ~60-80% of your maximum heart rate
20% of your work @ 80-90% of your maximum heart rate
5% of your work @ 90-100% of your maximum heart rate
You can estimate your maximum heart rate by subtracting your age from 220 (220 - your age = max HR).
This may be off by ~10-15 bpm, and to deduce your maximum heart rate with better accuracy you would need a max heart rate test.
However, even if the number you get is not accurate, it will still be a good enough estimate to put you around the appropriate ranges.
This all, of course, assumes you have a heart rate monitor.
If you do not, you can consider 60-80% of your max heart rate easy, 80-90% of your max heart rate moderate, and 90-100% of your max heart rate hard (max effort).
Oftentimes, these subjective effort ratings work even better.
It does not matter which cardio modality you choose use, either; whether it is running, cycling, rowing, a combination, etc.
The only point of note is that weightlifting or weight circuits will not work; as your cardiovascular/aerobic system will not be the limiting factor in such activities.
An example schedule of this could be the following:
Monday: 2 sets of 2 minutes of max effort running
Tuesday + Thursday: 30-45 minutes of incline walking
Saturday: 30 minute moderate effort run
Such a schedule could be done on it’s own or it could be used in conjunction with a strength program.
