Posted by Megan Fischer-Colbrie on Feb 12, 2015 8:55:20 AM
VO2 max (also referred to as maximal oxygen consumption, peak oxygen uptake) is the maximum rate of oxygen consumption as measured during incremental exercise, usually on a treadmill or cycle ergometer. Maximal oxygen consumption represents the aerobic physical fitness of an individual and is important in determining his or her endurance capacity in prolonged athletic activity. Given this definition, it should be easy to measure your VO2 max and see how your cardiovascular fitness stacks up, right? The answer, however, is not so obvious.
VO2 Max Levels
Current cutting-edge research in the relevance of VO2 max values for elite athletes reveals that while VO2 max is a decent measure of overall cardiovascular fitness, it is a poor predictor of athletic performance. VO2 max rates are expressed as an absolute rate (L/min), or a relative rate using kilograms of body mass (mL/kg min). The latter is used to compare the performance of endurance sports athletes. Contrary to popular belief, there is a high variation in VO2 max among the world’s most elite athletes.
The VO2 max levels of endurance athletes, such as swimmers, runners, cross-country skiers, cyclists, and rowers, tend to be the highest. Male endurance runners can reach a VO2 max of 85 mL/kg min while female runners can attain 77 mL/kg min. Among the world’s top male distance runners, where body fat percentage, mass, gender, and athletic ability are similar, VO2 max can range from 65 mL/kg min to 85 mL/kg min! This is a reminder to elite athletes everywhere that your VO2 max is only one piece of the performance puzzle.
What Affects VO2 Max?
A number of factors affect an athlete’s VO2 max, making it difficult to attribute performance differences between athletes to VO2 max values. Technique, mental strength, age, sex, changes in altitude, and other physiological traits can alter this value. Athletes generally use VO2 max as a measurement of their fitness and progress in training. However, if they want a more comprehensive picture, athletes should consider a few key elements in addition to VO2 max. Work economy, threshold, and VO2 max all directly impact one’s oxygen utilization during exertion. Oxygen utilization is ultimately what affects one’s speed and performance. Given this broader picture, work economy and threshold are also critical to the success of athletes.
Work economy influences your speed for a given amount of oxygen. Work economy includes a variety of characteristics, such as how you’re built (height, bone and tendon lengths, biomechanics), your mitochondrial efficiency (how well your mitochondria use oxygen), and the quality of your sport-specific technique. Thus, work economy varies more for athletes in highly technical sports, such as in swimming or cross-country skiing. Endurance athletes may also want to pay more attention to their threshold value. Whereas VO2 max measures peak oxygen consumption at the highest level of exertion, threshold is a measure of one’s exertional capacity at submaximal levels, and may be a more relevant value for athletes who consistently perform at a submaximal effort. Any middle-distance to long distance effort will rely more heavily on a high threshold than a high VO2 max. If you think of your threshold as your ceiling, then your VO2 max is the roof. Indeed, you cannot increase your threshold without raising your VO2 max to accommodate it. Ultimately, increasing one’s work economy, VO2 max, and threshold will all boost your oxygen utilization and performance.
Why VO2 Max?
So why have we been relying on VO2 max for so long? Stanford University Assistant Professor Mikael Mattsson points out, “If you want to take one measurement, VO2 max is the best. An increase in VO2 max is a good sign of accelerated recovery, speed, and general performance… but if I were serious about my training, I would not only use VO2 max, but also document these other factors, including threshold and work economy.” VO2 max is easy to measure and provides health information for the average person. The recreational athlete registers a value around 50 mL/kg min, while elite athletes generally register higher. Mattsson, whose current research involves “the Athlete Genome” and related projects surrounding endurance performance, also stresses that one’s VO2 max can increase over time due to training, but it eventually plateaus. Due to its high degree of variation among athletes, VO2 max may be more useful for self-comparison. This too, must be taken with a grain of salt.
VO2 Max Testing Mishaps
Amidst the noise of countless metrics for fitness tracking these days, athletes would do well to remember that performance can never be boiled down to a single statistic. In the old days of VO2 max, someone would collect the air expired by an individual and actually measure the gas concentration in the bag. Now, VO2 max is measured indirectly using an online system and gas analyzers that measure airflow. Mikael Mattsson comments, “You don’t really know if the machines are correctly calibrated. They might drift, and they might be off. Some researchers might even say every single machine is off and needs to be checked regularly.” He suggests athletes get their VO2 max checked at the same lab each time they choose to get tested to reduce variability from being tested on different machines. It may not be the case that your VO2 max is completely accurate, but your relative values can provide some insight. Eventually, the plateau in your VO2 max will happen, but this doesn’t indicate that your performance has plateaued. Mattsson also points out that measurements can register artificially high depending on whether the athlete took a deep breath immediately prior to the recording. In the United States, many labs record peak VO2 max values from the single highest breath. Mattsson states that you cannot trust the single peak value from a machine. Taking a VO2 max value from the average of peaks over 30 seconds to 1 minute would be a more accurate representation of peak oxygen consumption in reality.
Elite athletes can find their VO2 max value by completing a brief but intense exercise test in a lab. Over several years, this number may increase as the athlete attains higher fitness levels. Most importantly, elite athletes must remember the great genetic variability that exists even at the highest level of athletic prowess. Understanding your VO2 max, work economy, and threshold will contribute to your performance, but it is your hard work and commitment to your goals that will catapult you to success. To learn more about your exercise physiology, check out our recent posts at blog.bridgeathletic.com.
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