VO2 Max is defined as the highest rate of oxygen consumption attainable during maximal or exhaustive exercise. The terms VO2max, aerobic power, aerobic capacity, and maximal oxygen uptake are all terms used interchangeably. VO2max is widely accepted as the standard gauge of cardiorespiratory fitness. It is most often expressed in milliliters per kilogram of body weight per minute, , because oxygen and energy needs differ relative to size. It can also be expressed relative to body surface area, however, which may be more accurate when comparing children and oxygen uptake between sexes. The supply of oxygen is dictated by cardiac output and the amount of oxygen in the blood, which is determined by the amount of hemoglobin in the blood. It is also dependent on how well the tissue or muscle extracts the oxygen.
Oxygen consumption increases with exercise intensity. However, a point is reached where exercise intensity can continue to increase without the associated rise in oxygen consumption. The point at which oxygen consumption plateaus is the VO2max or a person's maximal aerobic capacity. VO2max is more useful as an indicator of a person's aerobic potential or upper limit than as a predictor of success in endurance events. This is because there are other factors besides VO2max that influence a competitor's success, such as mental attitude (ability to tolerate pain), running (or other activity) economy (how efficiently one runs), and lactate threshold (fastest pace that can be maintained without accumulating large amounts of lactic acid in the blood). A higher maximal oxygen consumption translates into a greater submaximal work capacity, which in turn means greater caloric expenditure in the same time while exercising or doing physical labor.
The average male aged 20-29 has a VO2 max of 44 to 51 and the average female aged 20-29 has a VO2 max of 35 to 43. (Lance Armstrong's VO2 max is 85 milliliters per kg.) The highest ever recorded VO2 max is 96 ml/kg/min, attributed to Bjørn Dæhlie, and 77 ml/kg/min in women. Both were cross-country skiers. The world-record test was purportedly taken when Bjørn was out of season; his physiologist, Erlend Hem, has stated it's very likely that Dæhlie could pass the 100 ml/kg/min score if the test was taken mid-season.
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Figures in tables from Astrand, 1960
Training and Performance
Recent research suggests that genetics plays a role in how much an individual can increase VO2max; amongst groups of people following the same training program there will be responders - those who make large gains, and non-responders - those who make little or no gains. There also seems to be a genetic upper limit beyond which further increases in either intensity or volume have no effect on aerobic power, which is thought to be reached within 8 to 18 months. Once that upper limit has been reached, further improvements in performance are still seen with training, however. This is attributed to the athlete being able to perform at a higher percentage of their VO2 max for prolonged periods. Two major reasons for this are improvements in anaerobic threshold and running economy.
A considerable amount of training is required to reach the upper limit for VO2 max, but much less is required to maintain it. Peak aerobic power can be maintained even after training is decreased by two thirds. Runners and swimmers have been known to reduce training volume by 60% for a period of 15-21 days prior to competition (a technique known as tapering) with no loss in VO2 max. Resistance training and intense 'burst-type' anaerobic training have little effect on VO2 max. Any improvements that do occur are usually minimal and in subjects who have low intial level of fitness. Resistance training alone does not increase VO2 max even when short rest intervals are used between sets and exercises. 
Determining VO2 max
Measuring VO2 max accurately requires an all-out (maximal) effort (usually on a treadmill or bicycle) performed under a strict protocol in a sports performance lab using open-circuit spirometry. 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. The test usually takes between 10-15 minutes and requires an athlete to be completely rested and motivated to endure the test long enough to find the true VO2 max. It's a painful point in VO2 max testing where the athlete transitions from aerobic metabolism to anaerobic metabolism. At that point, it is not long before muscle fatigue forces the athlete to stop exercising.
During the test, the athlete wears headgear which contains a non-rebreathing valve which the person holds in the mouth, like a snorkel. Room air is inhaled through the valve and air which is exhaled goes through a tube into a metabolic measurement cart. This cart measures the amount of oxygen and carbon dioxide in the exhaled air, as well as the volume of air. Knowing that room air contains 20.93% oxygen and 0.03% carbon dioxide, the amount of oxygen consumed can be computed after correction for barometric pressure, humidity and temperature.
Because direct measurement of maximal oxygen uptake is usually not feasible, as it requires the use of open-circuit spirometry, there are many alternative methods, both maximal and submaximal, which can be used to calculate or estimate VO2 max.
- Fick Equation - VO2 max is properly defined by the Fick Equation:
where Q is the cardiac output of the heart, CaO2 is the arterial oxygen content, and CvO2 is the venous oxygen content.
- Bruce Protocol -
- YMCA Cycle Ergometer Test -
- Astrand-Ryhming Cycle Ergometer Test -
- 12-minute Run/Walk -
- Rockport Walking Test -
- 1.5 mile Run -
- Cooper Test - The Cooper Test was designed by Dr. Kenneth H. Cooper in 1968 for military use. Essentially, subjects run as far as they can in 12 minutes. Test outcomes are based on the distance the subject ran, gender, and age.
Factors Affecting VO2 max
- Age - Generally, VO2 max is the highest at age 20 and decreases nearly 30 percent by age 65, however, this also varies depending on the individual and training program.
- Gender - Because of differences in body size and composition, blood volume and hemoglobin content, a woman's VO2 max is in general about 20 percent lower than a man's VO2 max.
- Altitude - Because there is less oxygen at higher altitude, an athlete will generally have 5 percent decrease in VO2 max results with a 5,000 feet gain in altitude.
Enhancing VO2 max
Because VO2max is a combination of max heart rate, cardiac output, and ability to process the oxygen carried in the blood, two ways of increasing VO2max are presented: increasing cardiac output and the ability of the body to extract oxygen from the blood. One can increase the cardiac output by making the heart larger and stronger, which occurs through prolonged endurance training. A trained athlete's resting heart rate is lower because it pumps more blood per beat than an untrained person's does. The body's ability to extract more oxygen out of the arterial blood is increased through endurance training as well.
Breaking this down even further (by training), there are two ways to increase VO2 max to its highest possible levels; increased volume and increased intensity. Interval training is one of the most commonly used methods for improving VO2 max, however, research has shown that it takes more than three hours of exercise per week to observe changes in heart rate, aerobic power. By dividing the workload into intervals, athletes can run for more total minutes at 100 percent of VO2 max than if they attempted a continuous run.
Studies highlight that sedentary people can improve VO2 max by over 20% when they begin a running program of 25 miles per week. By increasing mileage to 50 miles per week, VO2 max is improved a further 10%. Research seems to indicate that maximal VO2 max gains are achieved with a weekly running volume of 60 to 90 miles. This VO2max increase only occurs if intensity is maintained, not if intensity decreases as mileage increases.
Intensity has actually been proven to be more potent enhancer of VO2 max than volume. The world's leading work physiologists generally concur that VO2max is best improved by running at least at 70 percent VO2max, with the most benefits being at between 80 and 100 percent of VO2max.  Seventy percent of VO2 max corresponds to a pace that will bring your heart rate to 75-80 percent of maximum. Running faster than 100 percent of VO2 max will not improve it more than running at 100 percent of VO2 max. Running faster than 100 percent VO2max is likely to leave an individual more fatigued and unable to complete a high volume of work, however when the goal is not to improve VO2max, this may bring about other benefits.
Olaf Astrand suggests that all runners, regardless of running type, should race 800m regularly because they will be better able to cope with lesser amounts of lactate accumulated in longer and slower races.
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Sports Fitness Advisor. VO2 Max, Aerobic Power & Maximal Oxygen Uptake. sport-fitness-advisor.com. Retrieved on 2008-10-14.
- ↑ American College of Sports Medicine (2002). ACSM's Guidelines for Exercise Testing and Prescription, 6th ed., Philadelphia, PA: Williams & Wilkins.
- ↑ (2002). AFI 40-501, Air Force fitness program.. Department of the Air Force.
- ↑ (2002). MCO P6100.12 Ch.1, Marine Corps physical fitness test and body composition program manual.. Department of the Navy.
- ↑ Fagard R. (2003). "Athlete's Heart". Heart 89: 1455-1461.
- ↑ International Sports Sciences Association (2004). Fitness: The Complete Guide, 8th ed., Santa Barbara, CA: ISSA.
- ↑ National Acadmey of Sports Medicine (2004). Optimum Performance Training for the Health and Fitness Professional, 2nd ed., Calabasas, CA: NASM.
- ↑ National Strength and Conditioning Association (2004). Essentials of Personal Training. Champaign, IL: Human Kinetics.
- ↑ National Strength and Conditioning Association (2000). Essentials of Strength Training and Conditioning, 2nd ed., Champaign, IL: Human Kinetics.
- ↑ (1992). FM 21-20 Ch.1, Physical fitness training.. Department of the Army.
- ↑ 11.0 11.1 BBC (22 January 2002). VO2 Max - a Measure of Athletic Fitness. BBC.co.uk. Retrieved on 2008-10-14.
- ↑ 12.0 12.1 12.2 12.3 Hampson, David (n.d.). VO2 max: What is it, Why is it so important, and how do you improve it?. Cool Running. Retrieved on 2008-10-14.
- ↑ 13.0 13.1 NISMAT (2007-03-08). NISMAT Exercise Physiology Corner: Maximum Oxygen Consumption Primer. Nismat.org. Retrieved on 2008-10-14.
- ↑ Donche, Dan (2006). The Most Elite Exercise Tracker of All Time, 1 ed., US: Lulu.
- ↑ 15.0 15.1 15.2 15.3 15.4 Quinn, Elizabeth (June 9, 2008). What Is VO2 Max?. About.com. Retrieved on 2008-10-14.
- ↑ Jermyn, K.. VO2 max interval training. RunningOnline.com. Retrieved on 2008-03-11.
- ↑ 17.0 17.1 Horwill, Frank. Boosting vo2 max. Peak Performance. Retrieved on 2008-10-14.