In this article we’re going to breakdown everything you need to know about VO2 Max.  What exactly it measures, how the test is done, interpretation of the data, and real world applications for both health and performance.

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Table of Contents

1. What Is VO2 Max?
2. Why VO2 Max Is Important – The Science
3. VO2 Max Testing Procedure
4. Sample Report
5. The Data
   1. VO2 Max
   2. Heart Rate Zones
   3. Ventilatory Thresholds (VT1 & VT2)
   4. Calorie Expenditures
   5. Ventilation
   6. Tidal Volume
   7. Respiratory Frequency
6. Interpreting The Graphs
7. Heart Rate Zones & Lactate Threshold
8. Training Application
   1. Health
   2. Speed
   3. Endurance
   4. Pace / Tempo
   5. Other Factors
9. A Note About Nutrition
10. A Note About Biomechanics
11. Contraindications
12. Should I Get A VO2 Max Test?
    1. General Populations
    2. Athletes
13. Wrap Up

What is VO2 Max?

VO₂ Max stands for Volume of Oxygen (O₂) at Maximal exertion, or the maximum amount of oxygen your body can consume per minute, measured in milliliters per minute (ml/min).  Think of a VO₂ Max Test as your heart’s “One Rep Max.”  This is a crude analogy, but you get the idea.

A VO₂ Max Test is sometimes called a Max Oxygen Uptake Test.  It is the best assessment of cardiovascular and respiratory fitness, and one of the best indicators of overall health and fitness. 

Oxygen consumption has a direct correlation to power production, and maximal oxygen consumption directly relates to maximal power production.  The ability to generate power over time is called stamina.  

Whether you want more energy for daily activities, more power during strength training, or more endurance for any sport, knowing your VO2 Max and creating a training program based on it is the most efficient and effective way to train.  

Why VO2 Max Is Important – The Science

NOTE: This section gets a little technical, but many readers want to know the mechanisms behind cardio.  The rest of the article is practical information and does not require any scientific knowledge.

Your breath connects the atmosphere, or world around you, with an organism, you.  Your ability to process the atmosphere for your own function is essentially the definition of fitness.  

When your body inhales, it draws in oxygen through the nose and mouth, down your trachea (windpipe/throat) and into your lungs.  Oxygen goes from your trachea through your bronchi, a pair of tubes splitting to each lung, and reaches your alveoli, little sacs that fill with air, and are the end destination of your breath, or respiratory system.  

The alveoli are covered with capillaries, very thin blood vessels.  This junction is where oxygen is absorbed into the body through a process called diffusion, and is the connection of your respiratory and cardiovascular systems.  Oxygen is drawn into the bloodstream and circulated throughout the body to every single cell.  

In the cell, oxygen is metabolized through a process called cellular respiration.  Cellular respiration is the process of converting oxygen to usable energy.  Cellular respiration occurs in the mitochondria of the cells by breaking down glucose (sugar) in the blood with oxygen.  

Think of mitochondriales as the engines of your body, just like a car.  A car engine takes in gas and oxygen and converts it to mechanical motion.  Your mitochondria take glucose (gas) and oxygen and convert it into energy for motion.

The chemical process of cellular respiration is this:

glucose + oxygen → carbon dioxide + water + energy

C₆H₁₂O₆ + 6O₂ → 6CO₂ + H₂O + energy

Assuming your diet is adequate, the amount of oxygen you can take in is directly related to how much energy you can process.  Most healthy people have enough mitochondria inside of their cells to support basic daily living activities.  However, as intensity increases, the limiting factor becomes how many of these mitochondriales you have in your cells.  More mitochondria equals more capacity to convert oxygen and glucose into energy, meaning more power.  

Proper training requires the body to be acutely stressed, or overloaded, in order to provide a biological stimulus to generate more mitochondria.  Just like lifting heavier weights makes your muscles grow, breathing at higher intensities stimulates cellular growth.  This is the basis of developing cardiovascular fitness on a physiological level.

VO2 Max Testing Procedure

A VO2 Max test is performed in a controlled environment, on a cardiovascular machine, where intensity is gradually increased until the client reaches maximal exertion.  The client wears a gas analyzing mask for the duration of the test that continuously measures a variety of cardiovascular and respiratory metrics.

Here is a rundown of our testing procedure: 

• Preparation – Arrive rested.  Do not consume caffeine or exercise for five hours before your test.  Do not do intense exercise for 12 hours before your test (long runs, heavy lifting, HIIT classes, etc.). Do not eat three hours before your test.

• Set Up – We’ll measure your height, weight, ask about your goals and experience, and go over basic medical history (injuries, conditions, medications, etc.).  You’ll be fitted for the right sized mask and put on a heart rate monitor.  We’ll go over testing procedures and make sure you understand every step before we begin.

• Warm Up – You will begin walking at a casual pace for approximately 5 minutes to warm up while our wireless gas analyzer calibrates to the ambient pressure, humidity and temperature.  During this phase your coach will review testing procedures again.

• Testing – You will begin gradually increasing speed and/or incline by pre established increments.  The point of the test is to gradually increase resistance until you reach maximum exertion.  We use a proprietary protocol and time our tests to take approximately 10 minutes +/-.  

• VO2 Max – Max exertion can be reached in one of three ways: 1) we hit a predetermined heart rate we calculated (typically done for clients with health considerations), 2) the client signals they can’t continue, 3) there are two consecutive intervals where VO2 Max has declined

• Cool Down – After max exertion we bring the treadmill back down to your casual walking pace used for warm up.  This phase is to let your body clear itself out and to measure how quickly your metrics go back towards baseline.

• Review – Our system will generate an instant, detailed report we will review with you in real time. 

Sample Report

Below is a sample report we’ll reference throughout the rest of the article.  This was the third test done over about one year with a marathon runner from a local run club we work with.  Keep in mind, his results are exceptional, even for a conditioned athlete.  It provides good data for review.

The Data

• VO2 (ml/min) – Maximum oxygen consumption.
• VO2 (ml/min/kg)  – Oxygen consumption relative to weight.
• Heart Rate (HR) – The number of heart beats per minute (BPM).
• Heart Rate Zones – Specific training intensities determined by heart rate.
• Calorie Expenditures – Amount of energy (calories) used in a certain period of time
• Ventilation (Ve) – Volume of air moved through the lungs measured in liters per minute (L/min).
• Tidal Volume (Tv) – Volume of air breathed per breath in liters (L).
• Respiratory Frequency (Rf) – Number of breaths per minute.
• Ventilatory Thresholds
  • Ventilatory Threshold 1 (VT1) – The point during exercise at which ventilation  (V_E) starts to increase at a faster rate than VO₂.
  • Ventilatory Threshold 2 (VT2) – the point during incremental exercise at which an exponential increase in minute ventilation (V_E) relative to VO₂ (oxygen uptake) occurs.

Interpreting The Graphs

Reviewing the graphs provides insights beyond the report summary that can be used for specific training recommendations.  Noticing patterns, changes, and irregularities are important for creating effective, personalized training strategies.

There are three general ways a graph will display:

• Linear – a gradual and steady increase or decrease of a metric, represented by a relatively straight line
• Exponential – a point at which there is a noticeable increase or decrease in a particular metric, represented by a curved line
• Plateau – a period of time with relatively steady measure, after or between a linear and/or exponential period

Examples:

The red heart rate graph above is an example of a linear measurement.  Besides an initial spike in the first minute as the test begins, from minute two until VO2 Max is achieved heart rate steadily increases.  

The blue VO2 Max graph shows an example of an exponential curve just before the 5 minute mark.  From the start of the test until right before the five minute mark, the graph is linear, meaning VO2 Max is steadily increasing as intensity increases.  At the five minute mark there is a noticeable uptick in VO2 max, representing the point where the client began taking in oxygen at an increasingly faster pace.

The yellow Tidal Volume graph from about minute 3:30 – 4:30 represents a plateau.  The client started the test taking large breaths, followed by a few up and down breaths, before settling into a steady breathing rate from 3:30 – 4:30, before starting to breathe deeper again.

Heart Rate Zones & Lactate Threshold

Heart rate zones are traditionally broken up into five categories listed below.  In certain cases a coach may use different training zones, but the vast majority of training programs and fitness trackers use these standard five zones:

• Warm Up – A casual pace, similar to walking.  This phase is not intended for training adaptations, simply for what it’s named: warming up.

• Fat Burning – A low intensity pace where the body can easily process fat for energy via fat oxidation.  It can be maintained essentially as long as you have some fat on your body. *

• Endurance – A pace slightly more intense than fat burning but is still sustainable for long durations.  This zone marks the point where the body starts utilizing a bit more carbohydrate than fat, as carbohydrate provides energy faster than fat. *

• Vigorous – A demanding pace that converts the most energy to power, sustainably.    As long as the body is nourished, it can maintain this peak power, but typically is not sustained for endurance simply because it burns so much fuel it is not practical.

• Maximal – This is above your lactate threshold and is your peak power, but not sustainable.  By definition, your threshold is the point at which your body cannot chemically support sustained performance; the volumes of energy needed exceed production capability, and the volume of metabolic waste exceeds the ability to be cleared.

Lactate threshold, also known as anaerobic threshold, refers to the exercise intensity at which the production of lactate in the muscles exceeds its clearance rate.  This is significant because on a biochemical level, your body cannot continue performing at this level, and therefore fatigue will begin to set in.  

* A common misconception by many people is that if they want to burn more “body fat” they need to be in the “fat burning zone.”  This is a misunderstanding, confusing “body fat” with “dietary fat.”  Body fat is stored energy that can come from excess dietary fat as well as carbohydrates and even proteins;.  Dietary fat is a fuel source your body uses. Although in Zone 2 your body does burn a higher ratio of dietary fat than carbohydrate, training at higher intensities typically burns more total calories, and more body fat, even if the body is processing more carbohydrate.

Training Applications

How you train depends on your goals and results.  Your test results will provide numerous metrics to identify conditioning opportunities.  There are two main types of cardiovascular training:

• Steady State – maintaining a set speed or heart rate for a duration of time
• Cyclic / Interval – alternating between lower and higher speeds

Any variety of training protocols can be created by combining these two.  There are other forms of training such as breathwork, box breathing, meditation, visualization, etc., that can help improve lung capacity and nervous system control, as well as dietary and recovery recommendations, but for this article we will stick to strictly cardiovascular conditioning.

Let’s take a look at some training protocols based on specific goals:

Health – Health applications include weight loss, managing stress, nervous system response, and improving circulatory function.  Most health applications will fall in zone 2-3 and involve steady state cardio.  The objective here is simply maintaining a pace so your heart, arteries, capillaries, veins, metabolic and nervous system work continuously for a prolonged period of time.

Endurance – Endurance is the ability to maintain a pace for prolonged periods of time.  Endurance requires a person to continuously produce energy and eliminate waste, or metabolic buildup.  This is similar to health, but typically for longer durations and at higher intensities.  Endurance training is typically done anywhere from the middle of Zone 2 to middle of Zone 4.

Speed – Speed is the ability to accelerate and maintain a relatively fast pace.  In order to develop speed, there are two approaches.  1) increasing max speed / VO2 Max requires intervals above Zone 5 with a recovery typically in Zone 3.  For maximum sustained speed, training is typically done in Zone 4 up to your lactate threshold. 

Power – Power correlates with a sub threshold pace, typically zone 4.  This is the zone where you can sustain speeds without going into fatigue, but requires significant energy.  Maximal power, for example sprinting, will be done in Zone 5.

Sport – Sport applications should simulate real game or event play.  If you are training for an endurance event such as a marathon or triathlon, you will do a combination of speed work and endurance..

A Note About Nutrition

It’s important to note that the volume of oxygen you take in is equally important to your dietary intake.  Remember, oxygen is used to chemically process nutrients (glucose) in order to extract and use energy.  Oxygen binds to the carbon molecules in food and is exhaled as carbon dioxide.  You may have a great VO2 Max, but if you are not properly eating then the oxygen simply goes to waste.  On the other end, you can eat perfectly, but if you do not train at the appropriate intensities, you will not achieve your maximal power output.

A Note About Biomechanics

It’s important to note that proper form and movement are also critical to peak performance.  The same way you wouldn’t want a car to accelerate with the wheel turned, you don’t want to perform a race if your feet are turning out, your knees are falling in, or you aren’t fully extending your legs.  If you do not have good form, at best you aren’t transferring all your power efficiently, at worst, you can put yourself at risk of injury.

Contraindications

Getting a VO2 Test is one of the best ways to assess your current health and fitness level, and the most efficient way to train your cardiovascular and respiratory systems.  

Although many may benefit from a VO2 Max Test, there are generally two certain circumstances where we do not recommend one:

1. If the person has a physical limitation or injury that prevents them from reaching top speed, such as inflamed plantar fasciitis or severe hip or knee pain.
2. If there is a medical condition that would either place the person at risk or prevent them from reaching maximal levels, such as shortness of breath or any medications that significantly alter your heart rate.

In these cases, there is a physical limitation that prohibits maximal exertion.  Since your heart rate zones are based on your VO2 Max, you would artificially lower your heart rate zones, and training recommendations would not be representative of your cardiovascular capacity.  A body system other than your heart and lungs are limiting your ability to achieve maximum oxygen intake and should be addressed first.

You can do what’s called a VO2 Sub Max test, where you go until you reach an estimated perceived rate of exertion based on max heart  rate, but in our humble opinion, this is simply going through the motions to achieve a submaximal level that simply does not provide great insights.  

In this case, you’d be better off taking a “ground up” approach versus “top down,” as with finding your VO2 max.  The grounds up approach would be something like start with a warm up, find a pace you can safely maintain for 10 minutes, record your speed and average heart rate, then cool down. Repeat several times over a few weeks, record your speed and average heart rate each time. This is your baseline.  Once this feels easier, increase one variable at a time: length of time or speed.  Record average heart rate.  Repeat until average heart rate lowers by a few beats, marking a physiological improvement because you can now do the same work with less beats.  Then, progress again.

Should I Get A VO2 Max Test?

A VO2 Max Test is still the best way to structure a cardiovascular training program for most people without injuries, related medical conditions, and who are not taking medications that affect their cardiovascular and/or respiratory systems.

For an athlete, the value of VO2 Max testing is major.  One of the biggest problems for athletes, especially endurance athletes, is under recovery and time management.  So many times we see people logging hours and hours but not training at the right intensities to elicit change.  If you’re training for a triathlon and putting in 20, 30, even 40 hours per week, and some workouts aren’t at the right intensity, you’re simply putting more wear on your body, burning calories, and not recovering.  You’d quite literally be better off stretching and conserving energy.  If you’re training for speed, train for speed.  To increase lung capacity, train for that.  Don’t just drudge through miles.

For general populations, a VO2 max provides many insights into your internal fitness.  Training your cardiovascular and respiratory systems are one of the best things to do for longevity.  Knowing your heart rate zones will be a good approach for any goals related to weight loss, improving energy, metabolism and cellular function.