HOW VO2 MAX WORKS

reprinted from http://adventure.howstuffworks.com/outdoor-activities/triathlons/training/vo2-max.htm
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.
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)

Calculating VO2 Max

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. You can calculate VO2 using the following formula:
VO2 max = maximum milliliters of oxygen consumed in 1 minute / body weight in kilograms
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 = (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. Because of this, physiologists and sports scientists have devised other formulas you can use to calculate your VO2 max, using factors such as your age, resting heart rate, and maximum heart rate.
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) calculated using age = 208 – (0.7 x age)
RHR = Resting heart rate (beats/minute) = number of heart beats in 20 seconds x 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 = Weight (in pounds)
A = Age (in years)
G = Gender factor, G = 0 for females and G = 1 for males
T = Time to 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? Go on to the next page to find out how to use your VO2 number and ways you can increase it.

INCREASING YOUR VO2 MAX

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:
•30/30 and 60/60 intervals — alternating jogging and your fastest-paced runs
•Hill intervals — alternating runs uphill and jogging back down
•Lactate intervals — pushing muscles to their limits at your fastest pace
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. 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.