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The Science of Performance |
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Running Physiology – The State of the Art Part 1 - VO2max By Richard Gibbens If you’ve read much about the subject of running, you are probably aware that most modern training programs are very similar. The current thought on how to best train could be summed up with the slogan “run more”. Certainly each training program has its particular nuances, but the overall theme of modern training programs is that in order to run better, you should run more. This means that if you are currently running 25 miles a week, then by increasing your weekly mileage to 40 miles a week you will improve your performance. If you are already at 40 miles a week, then up it to 60. And so on, and so on. Where did this philosophy originate? And even more important, is it accurate? Is increasing volume the best way to improve your performance? Despite the popularity of the “more is better” approach, is there an alternate training approach that would yield superior results? These are the kinds of questions we will be addressing in this 7 part series on the current state of the art in running physiology. We will be examining the current dominant theory of running physiology, the research behind the theory, and the significant challenges to the theory. I will then advance an alternate theory of endurance physiology, supported by both research and empirical evidence. The objective is to provide you a balanced view of the facts with enough information for you to reach your own conclusions. The ultimate goal is that you will use the information provided to become a faster, healthier runner. Admittedly that’s a tall order, so let’s get started. VO2max: The current dominant theory of endurance physiology VO2max, Lactate Threshold, Aerobic capacity, Anaerobic capacity, and Tempo runs. If you have been running any length of time you have heard these terms and perhaps others that relate to endurance physiology. But, what do all these terms have in common? What is their relationship to running? And, perhaps most important, can you use them to run faster? All of the terms listed above have one major thing in common; they are all based on the theory of maximum oxygen consumption. It is widely promoted that the major limiting factor in running performance is your body’s ability to absorb and utilize oxygen. This is known as your VO2max. V is scientific shorthand for rate of volume flow, O2 is the symbol for oxygen, and max means the maximum rate of flow. So VO2max is the scientific way of expressing the maximum amount of oxygen your body can process. The belief in a VO2max is founded in research done in the 1920s by two British physiologists, A.V. Hill and Hartley Lupton. They were among the first to show that oxygen consumption increases as a linear function of running speed(1). Put simply, the faster you run the more oxygen you use. Using some assumptions that may or may not have been correct, Hill and Lupton postulated that shortly before a runner reaches maximum running speed, the rate of oxygen consumption reached a plateau and did not increase further(2). Although the runner could run a little faster, his body was not able to utilize more oxygen. At this point, the runner was said to have reached maximum oxygen consumption. Most importantly, the theory holds that since the runner has reached maximum oxygen consumption additional increases in running speed are not possible because additional oxygen to support the increased speed is not available. This forms the basis for the theory of VO2max. Armed with the belief that oxygen consumption was the limiting factor in running performance, coaches went to work developing programs designed to increase VO2max. After all, if VO2max is the factor that limits performance, then improving VO2max means an increase in running speed. However, VO2max is not easy to measure. It requires laboratory equipment and trained physiologists not available to most runners. On the other hand, heart rate (HR) can be easily measured. Since there is a correlation between VO2 and HR, the solution has been to base training on a percentage of max heart rate. When you see a training program instructing you to run at some percentage of your maximum heart rate, you know that program is based on the theory of VO2max, is designed to increase your VO2max, and hence to increase the speed at which you can run. It is almost impossible to find a modern training program not based on the theory of VO2max. It is by far the dominant theory today and has been adopted by practically all endurance sports. Sports such as running, triathlon, bicycling, and swimming all follow the theory of VO2max and base their training programs on improving VO2max. Now you understand the VO2max theory of endurance performance, where it comes from, the dominant effect it is having on training programs today, and why training programs are based on performing at some percentage of max heart rate. Here’s the big question. Is the theory of VO2max valid? Do athletes truly exhibit a VO2max and if so, is it the limiting factor in endurance performance? I will tell you right up front that I don’t believe the theory is accurate. Obviously, that is quite heretical and I risk the wrath of my fellow runners for my beliefs. However, I’ll back them up in part 2 when we examine the challenges to the theory of VO2max. References
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