THE MYTH OF VO2MAX TESTING
Traditional sports medicine, as well as most athletes and coaches, dictates that limitations in athletic performance occur because of oxygen, blood flow, lactic acid, or other factors. But these may not be nearly as important as once thought, as it’s the brain that monitors and regulates these and virtually all other activities, including muscle function, that limit our performance. For many decades, our maximum oxygen consumption—VO2max—has been the number many worship in endurance sports; but this supposed hallmark of endurance is not as significant as many coaches, scientists, athletes, and the sports press make it. Many athletes have their VO2max tested, and proudly, or frustratingly, display their number like knowing their cholesterol, blood pressure, or other special digit that, by itself, is misleading and insufficient.
Our VO2max is associated with our ability to use the oxygen in the air we breathe—it’s the maximum ability of our body to obtain this oxygen. It can be measured as the amount of oxygen (in milliliters) per kilogram of body weight per minute (ml/kg/ min). Men have significantly higher VO2max levels compared to women, and both lose VO2max with age. In addition to age and gender, a variety of other factors influence this number, especially training, but in some people training does not significantly increase VO2max. VO2max is also associated with maximum heart rate and with resting heart rate. Other factors, such as breathing efficiency, can significantly affect the outcome of VO2max testing.
There are two problems with making VO2max such an important number. The first has to do with how the test is administered, and a second is its relationship to performance.
A careful look at how the VO2max test is given will help explain why it’s not a good measure of human performance or athletic potential. Triathlete Mike Pigg was in my clinic for an off-season checkup, and we decided to visit a facility in New York City where some treadmill tests would measure, among other things, VO2max. The standard protocol was followed, which included telling Mike he was going to run at an increasingly rapid pace until he could not continue. He was not told how far or how long he would have to run. Nor was he given any pre-test meal instructions, and, although he worked out earlier that morning, he would only be given a couple of minutes to warm up. A tube was placed in Mike’s mouth, secured with a head strap, which would allow his oxygen and carbon dioxide to be measured; he would not be able to drink water or talk. Then the test began, with the treadmill pace taking Mike on a faster and faster pace, while at the same time the treadmill incline was gradually elevated. In less than ten minutes, the test was over because Mike reached a point of exhaustion and could not continue.
The test revealed how much oxygen and carbon dioxide his body could regulate, his respiratory rate, and other factors. While everyone around was impressed with how fast Mike could run without his heart rate soaring—he ran a sub-5:25 pace with his heart rate at 155—and by the other test results, including VO2 max, there was a big problem. Because he did not know how far or how long he was going to run, his brain did not participate, thus making the test an unnatural evaluation. Instead, it was more like a sterile, laboratory measurement providing numbers with little useful information. As a result, his brain could not allow his body to truly mimic a hard workout or race.
While the test was an interesting experience, it contributed nothing to what I recommended for Mike with his training, nor did it give Mike any useful information. In fact, testing Mike on the track, running at his maximum aerobic pace using a heart monitor, provided much more information—giving him confidence that he was getting faster while training only aerobically.
Dr. Timothy Noakes, author of the Lore of Running and an exercise physiologist who has been published extensively in scientific journals, has written much about VO2max testing. In an article in the British Journal of Sports Medicine (2008) titled, “Testing for Maximum Oxygen Consumption Has Produced a Brainless Model of Human Exercise Performance,” Noakes wrote that many people in sport “are apparently wedded to the concept that oxygen delivery alone determines the power output of the exercising limbs, and thus, they appear blind to a converse interpretation.” Noakes believes that the development of the VO2max test probably explains why most people in sports seldom consider that the brain’s effect on muscle function could be an important regulator of athletic performance. That’s because the VO2max test—still a gold standard—evaluates the athlete’s body without input from the brain. By not telling the runner being tested, for example, how far or how much time he or she must run, the brain is unable to most effectively monitor and regulate the physical activity. Instead, the test involves running to exhaustion—no endurance event is ever performed in this manner—we always know how far the race will be, and this enables the brain to prepare the body to complete the task in the most effective way possible, and without damaging the body.
The second reason why we should not be over-excited about VO2max is its relationship to endurance performance. Noakes and others are convinced that VO2max is a poor predictor of performance. Older male athletes, whose VO2max diminishes with age, often have lower VO2max levels than younger athletes, yet the older competitors often race better. And, most male endurance athletes have much higher VO2max levels than most women in the same sport, yet a significant number of women outperform these men.

There are at least seven different muscle fibers, with classifications based on a variety of features, from their microscopic appearance and energy utilization (sugar or fat), to the types of physical actions they produce (relatively fast or slow movement). These categories don’t always agree with one another, and as techniques improve even more fibers will be discovered and classified.

To simplify this complex subject, I’ll primarily discuss aerobic and anaerobic muscles, with some exceptions to further emphasize how training, diet, therapy, and other factors can significantly affect and change our muscles. For example, there are certain types of muscle fibers that are anaerobic but have the capacity to also function like a fast aerobic fiber. With the increase of aerobic speed, these muscle fibers become very important for gaining even more endurance. In addition, aerobic training, availability of fats for energy, and diets that are lower in refined carbohydrates can help program various muscle fibers to function for better endurance.

Muscle fibers are quite adaptable; in addition to growing in size, some can change from one type to another. A period of low or no training can result in the loss of aerobic fibers due to their conversion to anaerobic ones. Overtraining through emphasis on hard, anaerobic workouts without training the slow aerobic fibers may do the same. This “plasticity” or adaptability in the muscles is, in part, a response to our lifestyle environment—training, competition, diet, stress, and so on. Adaptability also enables older athletes to train and perform surprisingly well in endurance events. With aging comes an increasing loss of anaerobic fibers—one reason we lose speed as we get older. The result is a higher percentage of aerobic fibers in each muscle, making our potential for endurance greater with age. This is one main reason why sprinters reach their peak earlier in life while endurance athletes reach peaks later, often in the third or fourth decade, or beyond, and can still continue to perform at high levels for many years beyond that time.

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The adaptability of muscles also enables us to successfully treat common sports injuries, and rehabilitate more serious conditions, often very quickly. This is because most changes in muscles, whether from injury, ill health, or poor training, are not permanent.