CameronMartz
Fitness Instructor
I'm not cherry picking at all. I am just trying to avoid retyping previous posts or my entire book here. <g> I just listed the first three studies I found using the search terms "dcs vo2max" and directed those interested in learning more to click the "related articles" link. Doing so will lead anyone willing to put in the effort to a lot more on the subject.
The article you quote demonstrates how crazy it gets when studying exercise physiology. There is a difference between "VO2max" and "RELATIVE VO2max," though most of the time you see "VO2max," it is actually refering to "RELATIVE VO2max." Jolie is as guilty of doing this as I am.
In this case, "VO2max" is accurately described in your post above, but that is not what is important to either divers or athletes. What matters is how your cardiovascular capacity relates to your body size. This is where "relative" comes in. "Relative VO2max" is VO2max divided by body mass, giving you milliliters of oxygen consumed per minute per kilogram of body mass.
Why is this distinction important to divers? Because body mass is correlated with how much inert gas we can store. In other words, the more massive we are, the more places inert gas can go and the more inert gas we can store at the same pressure, more or less. So, it then becomes important to measure not what our maximum cardiovascular output is, but how it relates to the amount of inert gas we can store.
Think of VO2max as a measure of how fast we can move gasses into and out of our bodies at maximum effort because, in the end, oxygen and carbon dioxide consumption are limited by the same laws of diffusion governing the exchange of inert gasses such as nitrogen and helium (the roles of hemoglobin and bicarbonate have to do with gas solubility). We want to know how fast we can move gasses for each kilogram of inert gas "storage," not overall, because we only care about getting to equilibrium pressure quickly. We don't care how much gas we actually have to move in order to do it.
Anytime you see a correlation with BMI but NOT relative VO2max, you have to scratch your head and wonder "how?". Relative VO2max and BMI are linked by a common variable- body mass. If you lower your BMI, you raise your relative VO2max. It is purely a mathematical fact.
So, if Jolie really means "VO2max" and not "relative VO2max," then she's missing the point (which I doubt). If she's really refering to "relative VO2max," then the study quoted needs to be analyzed more closely before jumping to the conclusion that it is saying cardiovascular fitness is not important to dive safety.
Cameron
