# How to Calculate VO2 and VCO2

VO2 and VCO2 are important variables in measuring your body’s metabolism and efficiency during exercise. VO2 stands for the volume of oxygen that your body utilizes each minute. Similarly, VCO2 is the volume of carbon dioxide that you breathe out after transporting oxygen through your body. Taken together, these measurements can provide you with important information about the way your body burns fat and carbohydrates and can help you gauge your overall level of fitness.

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## Calculating VO2

The formula for calculating absolute VO2 is: VO2 (mL/min) = (HR x SV) x a-vO2. “HR” stands for heart rate in beats/min and “SV” for stroke volume, or the amount of blood the heart pumps in each beat. The phrase “a-vO2” is the difference between the amount of oxygen that goes into your muscles and the amount that comes out of them. As an example, if your exercising HR is 150 beats per minute, your SV is 100 milliliters per beat and your a-vO2 equals 0.14, then your total VO2 would be 2,100 milliliters O2 per minute.

## Measuring VCO2

The equation for calculating absolute VCO2 is as follows: VCO2 (mL/min) = VE x (FeCO2 – FiCO2). “VE” stands for the volume of air expired in mL/min, “FeCO2” stands for the fraction of CO2 in expired air and “FiCO2” stands for the fraction of CO2 in inspired air. If you breathe out 700 milliliters of CO2 per minute, then you would be breathing in 7 liters of air per minute, and CO2 would have to make up approximately half of the air you breathe in and 60 percent of the air you breathe out.

## Getting Tested

As you can see, VO2 and VCO2 calculations require a lot of precise information that most people do not have on hand. To get an accurate reading of these values, you will have to go to a well-equipped gym, health club or sports clinic where they have specialized equipment to measure VO2 and VCO2. A professional test will provide you with extremely accurate measurements at rest and during every level of physical activity. Many athletes perform these tests to assess their VO2max, or their maximum oxygen uptake, which is the gold standard for measuring levels of physical endurance.

## Estimating Your Numbers

While elite athletes and coaches may need to get the most accurate information on VO2 and VCO2, the average person can probably get by with rough estimates. Luckily, there are tests you can perform that require only a stopwatch and a calculator. For instance, you can estimate your VO2max by running as far as possible in 12 minutes, then measuring that distance (D) in meters along with your body weight in kilograms (BW). Then you can calculate your own physical fitness level with this formula: VO2max = [(0.0268 x D) – 11.3] x BW.