# How VO2 Max Works

By: Stephanie Crawford & Jennifer Walker-Journey  |

Runners and other athletes can find their VO2 max by taking a test similar to the one shown here, or they can use some of the mathematical formulas covered in this article. SolStock/Getty Images

Your body must have oxygen when you're exercising. If you're an athlete, especially if you participate in endurance sports like running, you may have considered the importance of oxygen when you're training and competing. A popular measurement athletes use is maximal oxygen consumption, or VO2 max. Your VO2 max is the maximum amount of oxygen your body can process to produce energy, or your maximum aerobic capacity. Improving it can help you run faster and more efficiently.

The technically correct way to write the name of this calculation is VO2max, with V denoting volume, O2 denoting the chemical formula for oxygen, and max as an abbreviation of "maximum." In scientific documents, it's sometimes written with a dot above the V, denoting the rate of ventilation. The more common term is VO2 max (occasionally written VO2max) [source: Davies].

The history of VO2 max measurement goes back nearly a century. Physiologist and 1922 Nobel laureate A.V. Hill was known for his years of research into how muscles work, and he made what were probably the earliest studies in maximal oxygen consumption. Hill theorized that a high VO2 max value was essential for success in distance running. He also said that your VO2 max is limited by the ability of your cardiorespiratory system to move oxygen to your muscles [sources: Bassett and Howley].

Contemporary theories about the VO2 max value challenge Hill's cardiorespiratory limitation [sources: Bassett and Howley, Davies, Bosch]. Despite these new theories, athletes and recreational runners alike have latched on to VO2 max as an important calculation for training. Other measurements like time, average speed and heart rate help you determine your physical fitness at a given point in time. VO2 max, though, is viewed as a measure of how efficiently your body is working overall. Some runners even see VO2 max as the "maximum potential" a person can accomplish, and they adjust their training tactics to aim toward that potential.

This article describes how to calculate your VO2 max, how to use that calculation and how to improve your VO2 max as part of improving your athletic performance.

## Calculating VO2 Max

Keep in mind some of the top distance runners in the world have had lower VO2 max numbers than some of their less-accomplished competitors, indicating that the VO2 max alone is not a clear predictor of success. Yellow Dog Productions/Getty Images

To understand the VO2 max formulas, let's first look at VO2, or the difference between the oxygen you breathe in and the amount you breathe out. The difference in oxygen levels between the air you inhale and the air you exhale indicates how much oxygen your body is using.

VO2 is measured in liters of oxygen consumed per minute and may be expressed in units of liters per minute (liters/minute). Your VO2 max is the maximum amount of oxygen your body can use. Since your body weight is used as part of this measurement, the units used are typically milliliters/kilograms/minutes.

The following is the basic formula for calculating VO2 max:

VO2 max = maximum milliliters of oxygen consumed in 1 minute / body weight in kilograms

You can calculate VO2 using the following formula:

VO2 = (milliliters of air inhaled per minute)(percentage of oxygen in the air inhaled) / (milliliters of air exhaled per minute)(percentage of oxygen in the air exhaled)

Do you know the maximum milliliters of oxygen you consume in a minute? Probably not. You can have this measured professionally at some medical facilities and training centers. The test typically involves breathing into an oxygen mask while walking on a treadmill at a certain pace for a certain amount of time. However, this test may be too expensive for the average recreational runner.

Advancements in technology have enabled some fitness trackers to provide VO2 max readings. These can cost anywhere from around \$100 to upward of \$1,000 or more depending on brand and features.

But you don't need fancy gadgets to calculate your VO2 max. Physiologists and sports scientists have devised other formulas that use factors such as your age, resting heart rate and maximum heart rate to calculate your VO2 max.

Here are two of these alternate formulas for calculating your VO2 max:

Using your resting heart rate and age:

VO2 max = 15.3 x (MHR/RHR)
MHR = maximum heart rate (beats/minute) = number of heart beats in 20 seconds multiplied by 3.
RHR = resting heart rate (beats/minute) = number of heart beats in 20 seconds multiplied by 3.

The Rockport Fitness Walking Test (RFWT) using a 1-mile (1.6-kilometer) walk:

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 = your weight (in pounds)
A = your age (in years)
G = gender factor, G = 0 for female, 1 for male
T = time to it took you complete the 1-mile walk (in minutes)
H = number of heart beats in 10 seconds at the end of the 1-mile walk

Other VO2 max formulas use data from a 3-minute step test or from a 1.5-mile (2.4-kilometer) run-walk test. You can find these formulas along with quick VO2 max calculators online.

Now that you know how to get your VO2 max number, what does it mean? Are you just average, or are you destined to be a world champion?

## Increasing VO2 Max

Advancements in technology have enabled some fitness trackers to provide V02 max readings. martin-dm/Getty Images

Your VO2 max indicates how much oxygen your body can use in your current physical shape. Historically, distance runners with a higher VO2 max have been considered to have the most potential for winning races and setting records. Studies over the years have rated different VO2 max values for different age groups, and athletes are consistently within those highest ratings.

In the resources cited for this article, the top-rated VO2 max categories for people in their 20s were 51 and higher for men and 44 or higher for women. As the athletes' age goes up, their VO2 max ranges at each level go down. For example, women in their 50s with VO2 max numbers of 31 and higher are rated excellent, but for women in their 20s, anything under 35 is considered poor. Different VO2 max studies often report different data in different ways, so be sure to look up your VO2 max in multiple resources to compare them and determine a reasonable number for yourself.

Exercise experts have found ways to make the most of the VO2 max number during your training, including ways to push that number higher. The most prominent of these approaches is high intensity interval training, or HIIT. Look for resources on how to develop the HIIT program that's right for you. The following are some HIIT workout formats you might try. Be sure to start with a 10-minute easy jog warmup before attempting these:

• 30/30 and 60/60 intervals: Run 30 seconds at your fastest pace. Then slow to an easy jog. Repeat until you have completed between 12 and 20 of each.
• Hill intervals: Run hard uphill for two to three minutes. Jog down to your starting point and repeat.
• Lactate intervals: This strenuous workout is best done on a track. Run hard for 0.5 to 0.75 miles (800 to 1200 meters) then reduce your pace to an easy jog for 0.25 miles (400 meters). Repeat until you have completed about 3 miles (5000 meters) of fast running total [source: Fitzgerald].

Though VO2 max training can boost your running performance and your fitness level, exercise experts across the board say not to make it the only priority in your training. One reason to keep VO2 max in perspective is that there are many factors that you don't have control over, such as your genetics, age and even your altitude [sources: Daley]. In addition, note that some of the top distance runners in the world have had lower VO2 max numbers than some of their less-accomplished competitors, indicating that the VO2 max alone is not a clear predictor of success.

Originally Published: Jul 14, 2010