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The Science of Performance |
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Running Physiology – The State of the Art Part 2 – The Challenges to VO2max By Richard Gibbens If someone offered you a guaranteed way to increase your VO2max by 25%, would you jump at the chance? If so, what effect do you think it would have on your performance? Is your current training program designed to increase your VO2max (and if you are using a heart rate monitor or conducting tempo, aerobic base building, lactate threshold or other such runs, then your program is based on the theory of VO2max)? In our running world VO2max is by far the dominant theory of endurance performance. In Part 1 of this series we explained what VO2max is, where it came from, and the effect it is having on training programs worldwide. Now we are going to explore the challenges to the theory of VO2max. There are 4 significant challenges to the theory of VO2max. The first is the lack of proof that VO2max exists, the second is lack of evidence that VO2max is the limiting factor in performance, third is the poor predictive powers of VO2max, and fourth is the fact that distance runners run at slower paces than VO2max. Let’s explore them in order. First, though the concept of VO2max is widely promoted, significant doubt does exist as to whether there is indeed a true VO2max. “Modern studies suggest that only approximately half of all tested subjects show true plateaus in oxygen consumption during maximal exercise; in the remainder no such plateaus are present” (1). If half of tested subjects do not exhibit a VO2max it is difficult to make the case that VO2max actually exists. Even physiologists can’t agree on the existence of VO2max. Second, physiologists that accept the theory of VO2max have assumed, but have not proven, that VO2max is the limiting factor in those subjects who show a plateau in oxygen consumption. There are no definitive studies that show that VO2max limits endurance performance; it is just assumed. This is a major assumption! What about those subjects that do not show a plateau in oxygen consumption – what is limiting their performance? Despite the efforts of many eminent physiologists, the question of whether VO2max is the limiting factor in endurance performance is still open and is unlikely to be proven anytime soon. With that being the case, basing a training program on a concept that has never been adequately proven, despite years of effort and research, is questionable at best. The third challenge is the poor ability of VO2max to predict running performance. If the limit to performance is the ability to process oxygen, then those with the highest VO2max would also be the fastest runners. That is not the case though. For example, Steve Prefontaine had a VO2max 16% higher than Frank Shorter. If VO2max is the sole determinate of running performance then we would expect Steve to have been 16% faster than Frank. However, their best 1 mile times only differed by 8 seconds and their best 3 mile time differed by .2 seconds – much less that the 16% predicted by VO2max. Other examples and numerous studies comparing VO2max to actual performance have shown the same thing; VO2max does not reliably predict the fastest runner. The fourth challenge has been mostly ignored by advocates of VO2max. At distances of 5K and beyond, runners do not race at their VO2max pace. They race at a pace less than VO2max. How is it possible to say that VO2max limits performance when you aren’t even running at VO2max? If VO2max really limited performance, then you should be able to run any distance at or only slightly slower than your VO2max pace. We all know that is not the case though. Now you know the major challenges to the theory of VO2max. VO2max has not definitively been proven to exist and furthermore, if it does exist, it has not been proven to be the limiting factor in endurance performance. Additionally, if VO2max does exist and is the limiting factor in performance, then those with the highest VO2max will be the fastest runners. Numerous studies show this is not the case. Lastly, distance runners don’t even attain VO2max during races of 5K and beyond. Some other as yet unidentified factor is obviously limiting their performance We now come to the most important point. You already know that just about every endurance training program is based on the theory of VO2max. Remember, if you use a heart rate monitor so you can run at some % of your max heart rate, or your program includes tempo runs, aerobic base building, lactate threshold or other such runs, you are following the theory of VO2max. However, if the theory is flawed, as I and others have suggested, does it really make sense to base your training program on it? If the theory is flawed then wouldn’t the training programs based on the theory be equally flawed? Lastly, if VO2max is not the limiting factor, then what is? Muscles are. That’s right; muscle contractility is the limiting factor, not oxygen capacity. I know this goes against everything you’ve read or been taught, so I will briefly build the case for muscles being the limiting factor later on in this series and will address it fully in a future series. In the meantime, since muscle contractility is the limiting factor, a major change in your training is due. Till then, keep on running. References:
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