Tuesday, December 7, 2010

What Is VO2 Max?

You may have heard the terms VO2 max and lactate threshold tossed around by athletes and coaches, but do you understand what they are, how they are measured and if they really matter? These articles help you make sense of the science.

VO2 max, or maximal oxygen uptake, is one factor that can determine an athlete's capacity to perform sustained exercise and is linked to aerobic endurance. VO2 max refers to the maximum amount of oxygen that an individual can utilize during intense or maximal exercise. It is measured as "milliliters of oxygen used in one minute per kilogram of body weight."

This measurement is generally considered the best indicator of an athlete's cardiovascular fitness and aerobic endurance. Theoretically, the more oxygen you can use during high level exercise, the more ATP (energy) you can produce. This is often the case with elite endurance athletes who typically have very high VO2 max values.

How Is VO2 Max Measured?
Measuring an accurate VO2 max requires an all-out effort (usually on a treadmill or bicycle) performed under a strict protocol in a sports performance lab. These protocols involve specific increases in the speed and intensity of the exercise and collection and measurement of the volume and oxygen concentration of inhaled and exhaled air. This determines how much oxygen the athlete is using.

An athlete's oxygen consumption rises in a linear relationship with exercise intensity -- up to a point. There is a specific point at which oxygen consumption plateaus even if the exercise intensity increases. This plateau marks the V02 Max. It's a painful point in VO2 max testing where the athlete moves from aerobic metabolism to anaerobic metabolism (See the article:Energy Pathways for Exercise). From here, it's not long before muscle fatigue forces the athlete to stop exercising. The test usually takes between 10 and 15 minutes and requires an athlete to be completely rested and motivated to endure the pain long enough to find the true VO2 max.

Vo2 max also can be estimated. There are a variety of protocols used to estimate VO2 max, one is called the Bruce Treadmill Test, but none are as accurate as direct testing.

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