What is VO2 max

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What is VO2 max, and why should runners care?
By americanrunning.org

VO2max is what determines aerobic capacity -- your ability to produce energy aerobically. Regular exercise trains your system to transport more oxygen-rich blood to your organs and muscles.Hardly a month of Running & FitNews goes by without some reference to VO2max. Maybe you have a vague idea of what it means.

Surely you know that more is better and that somehow good training increases yours. For many of us, "VO2 max" it evokes that uncomfortable feeling that someone is using a word you should know, and you would rather not confess that you don''t. 

If you fall into that category, here''s your cheat sheet for exercise physiology jargon, and you''ll never have to fake it again.

What the heck''s VO2max?

Your body works all the time to provide your muscles, skin, and all vital organs with the oxygen necessary for life. Each cell of your body needs oxygen to do its work and survive. The amount of oxygen demanded changes depending on the amount of work being done.

As the demands increase (for example, while running) the rate of respiration increases, and the amount of blood being pumped by the heart increases. When we talk about cardiovascular fitness, we are basically talking about VO2max.

VO2max is what determines aerobic capacity -- your ability to produce energy aerobically. Regular exercise trains your system to transport more oxygen-rich blood to your organs and muscles.

A non-exerciser who tries to run quickly exceeds his body''s capacity to supply the oxygen needed to keep the muscles working. He stops, gasping for air, muscles aching with fatigue, his heart pounding with the effort to reload oxygen to the system. With regular effort, the body makes a variety of adjustments that increase its ability to deliver and use oxygen on demand.

VO2max is simply a way to quantify that oxygen-delivering ability. So, here goes:

VO2max is the maximum amount of oxygen that your heart can pump and your muscles can use in a given period of time.

Sounds simple. It is determined by multiplying heart rate (beats per minute) times the volume of blood pumped with each heart beat times the fraction of oxygen pulled from the blood and used. It is expressed as milliters of oxygen used per kilogram of body weight per minute (ml/kg/min).

Why should a runner care?

As a runner, you have already enjoyed the benefits of major improvements in VO2max. If you became a runner from the base of a sedentary lifestyle, you know well what VO2max improvements mean. You only need to visualize your "before" and "after" self.

However, within certain genetically imposed limits, the right kind of training can produce even greater increases in VO2max. The result can be faster, more efficient running, and that''s why a runner would care.

What''s my VO2max?

Sedentary men have VO2max values in the 40ml/kg/min range, while elite runners tend to have values from 70 to 85ml/kg/min. The comparable values for women are lower due to higher body-fat composition and lower hemoglobin levels.

To calculate your own VO2max, you could take a treadmill test while connected to a tube measuring your exhaled gases as you gradually push yourself to a maximum output. Or you can use estimates to find your target pace of 95% to 100% of VO2max.

Training at that level of exertion will help to increase the amount of blood circulated with each heartbeat, and to increase the amount of oxygen your muscles can get from your blood.

Although heart rate and VO2 max are not the same, maximum heart rate can help you target a running pace that pushes the anaerobic threshold and therefore increases VO2 max.

Maximum heart rate is estimated by subtracting your age from 220. Multiplying that number by 0.95 and 0.98 will give you figures corresponding to 95% and 98% of maximum.

Working in that zone of intensity until you must slow down, recover and do it again, over a distance of a few miles -- this is the kind of VO2max interval training that will improve your cardiovascular output, speed and endurance.

Now you know what''s up with VO2max -- and you can use it to your advantage

© The American Running Association, a non-profit, educational association of runners and medical professionals dedicated to promoting running nationwide. For over 30 years, the American Running Association and its professional division, the American Medical Athletic Association, have provided information and support to runners nationwide.