UNDERSTANDING VO₂ MAX
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What is VO₂ Max
A VO2 Max Test is a measurement that reflects a person’s ability to perform sustained exercise. It is generally considered the best indicator of cardiovascular fitness and aerobic endurance. The actual measurement is “milliliters of oxygen used in one minute per kilogram of body weight.” It is suitable for a wide range of individuals, from the sedentary to elite athletes.
VO2 Max is the maximum rate of oxygen consumption that can be attained during the most intense exercise possible. The measurement requires that the subject breathe into an oxygen consumption analyzer during an all-out effort (usually on a treadmill or bicycle) as part of a graded exercise protocol. These protocols involve specific increases in the speed and intensity of the exercise. While exercising, the person wears a mask to collect all the air he breathes in and out for a measurement of the volume of exhaled gas and the concentration of oxygen in that exhaled gas. This determines how much oxygen is used during each minute of the exercise test.
A person’s oxygen consumption rises in a linear relationship with exercise intensity — up to a point. There are specific physiological markers (AeT, AT) that can be detected throughout the test as oxygen consumption is measured. Eventually, oxygen consumption plateaus even if the exercise intensity increases. When the person is no longer able to keep up with the oxygen demands of his muscles and complete fatigue forces him to stop exercising, then his oxygen consumption has reached a maximum, and VO2 Max can be calculated. The test usually takes between 10 and 15 minutes
VO₂ Max Testing is as easy as 1, 2, 3!
1. Put on a heart rate strap and face mask.
2. As directed by your trainer, you will start exercising on a treadmill or cycle. You will start at a low intensity, gradually increasing the intensity of exercise over a period of 6 to 20 minutes.
3. When you are finished, your trainer will give you a simple, insightful report that can be uploaded to an easy-to-use app.
To get the most out of your VO2 Max Test, be sure to refrain from exercise or endurance training for 24-hours prior to test, avoid food, tobacco, alcohol, and caffeine for at least 3 hours before testing, and continue medications as usual.
A complete VO2 Fitness test can give trainers and clients the tools to set realistic goals and assess improvement. Studies show that previously sedentary people training at 75% of aerobic power for 30 minutes, 3 times a week over 6 months increase VO2 Max an average of 15-20%. Many people are inefficient exercisers, with no understanding of what specific heart rate, intensity or duration would best help them reach their specific goals such as fat burning, endurance training, or cardio conditioning. An initial VO2 Max test can clarify the specific target heart rates that will enable each individual to reach their fitness goals more effectively, with less fatigue and fewer injuries. Periodic retesting provides motivating feedback as the fitness program progresses.
The test also determines the number of calories burned during every level of exercise, providing valuable information when designing a weight loss program. And if CO2 is measured during the test, a Respiratory Exchange Ratio (RER) can determine the proportion of energy coming from carbohydrates and fats at various levels of exercise intensity. Since physical conditioning and exercise intensity affect these proportions, this information can be very helpful when designing a workout intended to burn fat.
VO2 Max testing is a valuable tool for serious athletes to assess performance and evaluate training regimens. Even though extensive training can sometimes cause an athlete to reach a plateau in VO2 Max, he can still use his VO2 Max test results to make further improvements in performance. This is accomplished as he pushes to increase anaerobic threshold (AT) and maintain that threshold for longer periods of time. This enhances both endurance and cardiovascular performance.
The anaerobic threshold (AT) is defined as the level of exercise intensity at which lactic acid builds up in the body faster than it can be cleared away. Lactic acid build up generally leads to muscle fatigue and soreness. Vigorous effort can be sustained for an extended duration at exercise intensity levels below the anaerobic threshold. AT can be detected by 2 different means: Ventilatory Threshold, or Respiratory Exchange Ratio threshold.
Respiratory Exchange Ratio (RER) is the ratio of expired carbon dioxide to oxygen uptake at the level of the lung. When Carbon dioxide production exceeds oxygen uptake, the RER crosses 1.00. This is anaerobic threshold.
Ventilatory Threshold (VT) is the point during progressive exercise in which ventilation increases disproportionately to oxygen uptake. Ventilation increases to rid the body of the excess Carbon dioxide from lactic acid build up. AT is detected by pinpointing the take off (rising) point in the Ve/VO2 ratio. (Meyers, 1996)
Lactate Threshold is a reference to the accumulation of Lactate in the blood. There are some inconsistencies in the terminology, though. Some use the term to denote the initial rise in lactic acid production. More often, Lactate Threshold is used to describe the maximum steady state effort that can be maintained without lactate continually increasing. This abrupt increase in blood lactate levels is also referred to as the lactate turn point (LT), lactate inflection point (LIP), or onset of blood lactate accumulation (OBLA). (Roberts & Robergs 1997)
The Anaerobic Threshold is defined as the level of exercise intensity at which lactic acid builds up in the body faster than it can be cleared away. Because this is measured by Ventilatory responses (Ve/VO2 or VO2/VCO2), it is often more accurately termed Ventilatory Threshold (VT). (Meyers, 1996)
Respiratory Exchange Ratio (RER) is the ratio of expired carbon dioxide to oxygen uptake at the level of the lung.
Respiratory Quotient (RQ) is the ratio of expired carbon dioxide to oxygen uptake at the level of tissue or cells. Sometimes this term is used interchangeably with RER, but that is incorrect. A VO2 Max test measures RER. (Meyers, 1996)
The key to determining Anaerobic Threshold (AT) during a VO2 Max test is to detect the point when the body is forced to expel the surplus CO2 produced as a result of excess lactate. This can be determined one of 2 ways:
- Measuring VCO2/VO2 (volume CO2/volume O2) and detecting the point when that ratio (RER) equals 1.00. This is the Respiratory Exchange Ratio method.
- Measuring Ve/VO2 (Minute Ventilation/volume O2) and detecting the respiratory compensation point. This is the ventilatory equivalent method.
Multiple studies (1,2) have shown that both methods are valid and reliable for determining AT among healthy subjects. KORR offers products that utilize both methods of AT detect to best meet customer needs. A comparison of methodologies in detection of the anaerobic threshold. Dickson K, Barvik S., Aarsland T, Snapinn S, KarlssonJ. Circulation 1990 Jan;81(1 Suppl):II38-46. A new method for detecting anaerobic threshold by gas exchange. William L. Beaver, Karlman Wasserman, and Brian J. Whipp Journal of Applied Physiology 60:2020-2027, 1986
Women typically tend to have a lower VO2 Max than men.
For men and women, VO2 Max will decrease by 10% per decade regardless of age and exercise activity.
VO2 Max is unique to each person and directly proportional to their height, weight, and body surface area. VO2 Max correlates 0.63 with body mass, 0.85 with fat-free body mass, and 0.91 with active muscle tissue.
VO2 Max is reduced for residents of temperate or tropical areas (compared to those living in circumpolar regions). Also, VO2 Max is reduced by approximately 26% at an altitude of 4,000 meters. This reduction increases as altitude increases.