VO2 max (V=volume, O2= oxygen) is the measurement of the maximum amount of oxygen utilized while exercising.
It may seem simple and inherent: you breathe in, you breathe out, you keep the workout going.
The importance of maximal oxygen consumption for exercise and the idea of the VO2 max was brought to into the fold by AV Hill, the 1920s by Nobel Prize winner from Cambridge. And it wasn’t even until the 1950s and 1960s that methodological studies were conducted to gather the accurate physiological elements required for VO2 max measurement of an individual.
Tools to measure VO2 max were created by Henry Taylor and his colleagues over the course of 12+ years at the University of Minnesota lab. Studies were conducted on military draftees who were conscientious objectors. These subjects were essentially at Taylor’s disposal; over a 12-month timeframe, they exercised for one hour a day, six days, and he collected data using methods that were groundbreaking at the time (but are still used today).
Now hundreds of labs all over the world can test conduct a VO2 max test. It used to be only elite athletes had access to these tests, but they’ve become a prevalent benchmark in endurance sport for those at all levels looking to improve their athletic performance.
Why consider testing VO2 max as part of your training? It’s possibly the barometer for aerobic fitness.
Why Muscles Need Oxygen to Function
Muscles (and all cells) require energy production to function.
Energy inside cells comes in the form of ATP. Most of our ATP is created through the breakdown of metabolic substrates (food) using oxygen, resulting in CO2 and water. This means oxygen is really important, and as you exercise, energy requirements go up–so you need more oxygen.
Oxygen is absorbed into the blood by the lungs. It binds to a special protein called hemoglobin inside red blood cells. It then travels in the blood, and is pumped by the heart to the rest of the body, getting released in the tissues (including muscle) where it is used to breakdown our food to release energy.
The harder we exercise, the more we breathe and the more our heart pumps; this helps to deliver more oxygen. These are some of the critical factors that influence an individual's VO2 max.
However, muscles can make energy without oxygen in a process called anaerobic respiration. The only fuel that can be burned anaerobically is carbohydrate, being converted into a substance called pyurvate through glycolysis and then into lactate via anaerobic metabolism.
Build up of lactic acid happens when production occurs faster than our ability to clear it out. The blood becomes more acidic, which in turn can compromise muscle function.
Clearly, fuel source is an important factor relating to the amount of oxygen consumed. At higher intensities of exercise, muscles burn mainly carbs and at lower intensities, they burn more fat.
BHB is relatively oxygen efficient: when a working muscle burned both BHB and carbs it produced more power with the same amount of oxygen, increasing efficiency by 28%.
Muscles are like an engine that need gas (oxygen and fuel) to function.
What’s Behind a VO2 Max Number?
The maximal rate at which an individual can process oxygen is usually expressed in milliliters of oxygen per minute per kilogram of bodyweight–this is the relative number most often considered a VO2 max.
An average, untrained male age 20-29 has a VO2 max of 35 - 40ml/kg; of the same age, the average, untrained female has a VO2 max of 27 - 30ml/kg.
You’d imagine endurance athletes, who need to make energy during long periods of aerobic exercise typically have the highest maximal oxygen uptake. Masters of endurance performance, like cyclists and runners, are usually near the top, with more explosive athletes, like weightlifters, near the bottom.
Elite male runners can have a VO2 max values of 85ml/kg; elite female runners can have 77ml/kg. Miguel Indurain, who won the Tour de France five times, reported to have had a VO2 max of 88 at his prime, and Lance Armstrong had an 85.
But which athletes are at the peak of VO2 Mountain? That’s cross-country skiers.
Bjørn Dæhlie, a Norwegian cross-country skier, recorded a VO2 max of 96ml/kg. The result came out of season for Dæhlie, and his physiologist claimed he could have gone over 100ml/kg. He had the record for years but in 2012 was dethroned by another Norwegian, an 18 year-old cyclist named Oskar Svendsen, who reported logged a 97.5ml/kg. Remember, these scores don’t appear in peer-reviewed literature, so questions always arise about their accuracy.
Animals have also been tested. Thoroughbred horses have been measured to have a VO2 max score of 180ml/kg; while Siberian huskies who ran the Iditarod notched a whopping 240ml/kg.
How to Find Your VO2 Max
Do you know how many milliliters of oxygen per minute per kilogram of oxygen your body can consume at all-out effort? Probably not.
Training Centers
These supply the most accurate VO2 max testing. Professional labs (and sometimes training facilities) with exercise physiologists provide these tests, which are typically conducted by breathing into an oxygen mask while walking on a treadmill for a certain amount of time at a specific pace.
The only downside: it’s expensive.
During lab tests, a facemask is placed on subjects to measure the volume and gas concentrations of inhaled and exhaled air. Similar to lactate testing in a sports lab, athletes run on a treadmill (or sometimes use a stationary bike or rowing machine, depending on sport) and the exercise intensity increases every few minutes until exhaustion (read: you start having tunnel vision, hit the red stop button and collapse into a sweaty heap). The test is designed this way to achieve maximal exercise effort from the subject.
Usually, heart rate is measured through the test so you get data on your resting heart rate all the way up to maximal heart rate. Athletes will receive their ideal heart rate zones for warm-up, aerobic, anaerobic and uber-tough intervals.
The most valuable of this group might be the heart rate between aerobic and anaerobic exercise: the anaerobic threshold. Training will be geared toward improving this point, at which the body begins to accumulate lactate in the blood.
Similar tests can be replicated outside of labs with less accuracy.
Simple Heart Rate Test
Another way to roughly estimate VO2 max also makes use of heart rate measurement.
First, find your resting heart rate. Most fitness trackers can provide this number, but if you don’t have a fitness tracker, you can go old school. Find your pulse and set a timer for 60 seconds, counting the number of beats in a minute.
Then, find your maximum heart rate. This formula might oversimplify things, but it’s effective for the purposes of a loose VO2 max calculation. To find your max heart rate, subtract your age from 220. So, if you’re 30 years old, your maximum heart rate is 190 beats per minute (bpm).
Use this formula to find your simple VO2 max: 15 x (max heart rate / resting heart rate).
For example, if your maximum heart rate is 190 and resting heart rate is 80:
VO2 = 15 x (190/80)
VO2 = 15 x 2.4
VO2 = 36.6
This isn’t the most accurate formula, but it can provide a good starting point for training to improve VO2.
The Rockport Fitness Walking Test (RFWT)
This walking test can also calculate a VO2 max, and studies have proven its accuracy.
First, stretch and warm up. Then, find a track or mostly flat surface on which to walk a mile as fast as possible. It’s important to walk, and not to cross over into jogging territory. After walking exactly one mile, note exactly how long it took and your heart rate at the end of the mile. Using those numbers, you’ll be able to find an estimated VO2 max using this formula:
VO2 max = 132.853 - (0.0769 x W) - (0.3877 x A) + (6.315 x G) - (3.2649 x T) - (0.1565 x H)
W = weight (in pounds)
A = age
G = gender (1 for men, 0 for women)
T = time to complete the mile (in minutes)
H= heart rate
VO2 Max for Cyclists
Power is the golden egg of data for cyclists. It’s the gift that keeps on giving, as it provides some insight into finding a VO2 max, when combined with some field testing.
Pedal for 20 minutes at a maximum, yet sustainable, effort. Cyclists should monitor their power meters, maintaining consistent intensity while incrementally increasing wattage the first three minutes until finding a power output that can be maintained for the rest of the test. This should be a wattage similar to high-intensity rides or races. Use this formula to find your VO2 max:
VO2 max = [(10.8 x W) / K] + 7
W = average wattage
K = weight in kilograms
Improving Your VO2 Max
Two major factors contribute to a high VO2 max: the amount of oxygen you can transport and your muscle physiology.
Oxygen transportation includes a strong heart pumping blood through the body, with hemoglobin-dense blood, a high blood volume and high capillary density in the muscles. Better oxygen transport leads to higher VO2 max. Muscle physiology means how many muscle fibers you have, how big they are, how many mitochondria they are, and how strongly you can activate them during exercise. More aerobic, oxygen guzzling muscles equals a higher VO2 max.
Similar to lactate training, a training program can be implemented to improve VO2 max and help increase physical fitness, improving the way your body utilizes oxygen. Training is designed to have you spend as much time as possible at 95% - 100% of your current VO2 max as possible.
Limiting factors like gender, genetic makeup, and age all have an impact on an individual VO2 max–but training can always improve this number. Because lactate threshold and VO2 max are linked, check out our blog for additional ways to train with lactate in mind.
A note: since body weight is a factor in VO2 max, less body mass will inherently improve your score.
Interval training often results in the most improvement of VO2 max.
High-Intensity Training: Long Intervals
If you are good at pacing yourself, sessions made up of long (4 minutes or so) intervals at your hardest sustainable effort are a good way to increase VO2 max. Between each interval, you should keep moving; active recovery will keep VO2 elevated during the process. Plan to do 4-6 sets.
The 4x4 minute workout is a classic in all sports: running, cycling and rowing research has proven its efficacy.
The idea is to save enough energy so that your last set is the hardest intensity. If you are running on a track or watching your power on the bike, ensure you’ll be able to go your hardest on the last set. Pace this right and you should be dreading the last interval. By holding a pace that’s at the upper limit of your ability, you overload your heart, lungs and muscles, forcing them to adapt to deliver and take up more oxygen.
In one research study, athletes who did a similar workout improved their VO2 maxes by 10%.
High-Intensity Training: Short Intervals
If you can't bring yourself to suffer four minutes of near-max intensity, you can go for shorter intervals–but they have to be an even higher intensity to provide a benefit. Short interval sprints of under one minute can also improve VO2 max as long as they’re conducted at almost maximal effort level.
The exercise test here is 8-10 sets of 1 minute sprints. Again, make sure you are properly warmed up–these workouts carry a risk of injury because of the amount of power produced. You have to give it your all during each interval without holding anything back.
From the same study mentioned above, those doing ten sets of one-minute high-intensity sprints on a treadmill at maximum rate (with a 1 minute rest in between each interval) increased VO2 max by 3%.
Time to exhaustion, plasma volume and hemoglobin mass increased with this routine. However, results demonstrated that long interval training garnered the most dramatic results.
VO2 Max: Training Your Body to Use Oxygen
Being able to use a high volume of oxygen with a high degree of efficiency is one of the best indicators of endurance fitness there out there. Many factors contribute to this measurement, but what it comes down to is training–athletes must train to increase VO2 max.
Some athletes are better equipped for high VO2 maxes. Runners, cyclists and rowers sit near the top of the totem pole, but cross-country skiers have typically reigned supreme. Regardless of your sport, a high VO2 can be a great gutcheck for your fitness level at a physiological level.
Because oxygen is so vital to our muscle function, we should be adept at using it efficiently.
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