Your body needs oxygen all day long, but it needs more when you are exercising. VO2 max measures maximum aerobic capacity by assigning a number to the maximum amount of oxygen your body can turn into energy. The "V" denotes volume, "O2" is the chemical formula for oxygen, and "max" is short for "maximum."

## Is VO2 Max a New Measurement?

Not at all. A.V. Hill, a Nobel Laureate and physiologist, first proposed the measure in 1923, and though it was standardized decades later, it has not changed much from the calculation introduced nearly a century ago. While it's been studied, argued, athletes have rarely wavered in their approach to maxing out the number and continue to attempt to boost their numbers and use it as a training tool.

## Why Measure VO2 Max?

For people training for marathons, triathlons, and other endurance sports, the VO2 max can be used to compare numbers with other athletes and also identify the optimal level at which one can or should exercise. The number is a general measure of overall cardiovascular fitness: the more oxygen you can process, the more adenosine triphosphate (ATP), an energy-carrying molecule, you can produce.

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## How Is VO2 Max Calculated?

Professional athletes will most likely visit a sports performance lab to have their VO2 max calculated, though there are ways of estimating this on your own. Professional testing employs a treadmill or bicycle, and the intensity of the tasks the subject is required to perform are measured to the millisecond. The goal of the test is to find out an individual's plateau for turning oxygen into energy. The test only takes about 10 to 15 minutes and requires the athlete to show up well-rested and ready for maximum output.

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## What To Expect at a VO2 Max Test

While a treadmill is the most common piece of equipment used, cyclists and people with knee issues may use a stationary bike, instead. Before the appointment, the subject should avoid exercise for at least 24 hours, and steer clear of alcohol, tobacco, caffeine, and food for at least three hours before. The athlete is outfitted with a mask connected to a machine that measures breathing rate and volume, as well as oxygen and carbon dioxide emission levels. The technician will also apply a heart strap to measure heart rate during this short test.

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## Taking Multiple VO2 Max Tests

Your VO2 max value in a vacuum is not all that helpful. However, as a way of measuring your progress, it is a useful tool to have at your disposal. Additional tests allow you to measure your progress with a quantifiable number on which to base your success while preparing for an endurance race such as a marathon.

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## Interpreting Your VO2 Max Score

The best comparison is the changes in your own VO2 max score over a period of time, but percentages of other athletes may also be compared. Charts that break down the "ideal" VO2 measurement for your gender and age can be found online or obtained from a personal trainer.

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## Factors and Limitations To Your VO2 Max Score

VO2 max scores generally peak around the age of 20 and will decline by roughly 30 percent before age 65. Comparisons between sexes are not useful, as VO2 values in female athletes are always higher than men at the same level of fitness. Altitude also plays a role: the higher you are, the less oxygen available for your body to process. As a rule of thumb, your VO2 will decrease by about five percent per 5,000 feet of altitude.

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The VO2 max isn’t the be all end all, especially for an endurance athlete. There are considerably more important factors to consider when trying to push yourself to your limit. Mental preparation and sheer willpower go a long way, as do proper form and technique. Lactate threshold training and nutrition are of supreme importance as well. Yes, your VO2 number is an element of success, but no more so than any of these other factors.

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## Who is Firstbeat?

Firstbeat is a leader in heart rate-based analytics. The company has developed wearable VO2 max devices that track the wearer's levels, run algorithms, and analyze VO2 numbers without the athlete ever setting foot in the lab.

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## How Accurate are Wearable VO2 Max Trackers?

Though a professional test is always more reliable, VO2 max wearable trackers are surprisingly accurate. Firstbeat claimed a 95% accuracy, based on 2,690 runs from 79 individuals in the company's first white paper.

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