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>Dan
>Whoa? Why is it impossible for a fat athlete to have a high VO2 max, I
think
>it is improbable but not impossible.


Lets say Dan Volker weighs 205 pounds ( bodyfat 17%), and has a VO2 max of
55ml/kg . If Dan gaines 20 pounds, he loses VO2 max, and ends up with a VO2
max of 50ml/kg
If instead of gaining,  he lost 20 pounds, he increases his VO2 max to
60ml/kg ----the difference of just 5 ml/kg  is a huge determinant in an
endurance contest. It is the difference between being able to ride a bike at
24 mph, or 27 mph----if you have ever ridden a bike, you will know there is
a huge difference in people with these two different max sustainable speeds.
In the Dan Volker case, the 55 ml/kg value represents 15 years of intense,
competitive level Cardiovascular training. Without it, Dan would be closer
to 40 ml, and the weight gain dropping jim closer to 35 ml.

In the scheme of things, this 20 pounds is not fat to the degree of obesity.
Dan would have to grow to perhaps 300 pounds.  With all his cardio training,
this would have him at a VO2 max of 37 ml/kg-----but if he did not have the
cardio training,  it would be closer to 14 to 17 ml/kg  .... clearly gas
exchange would be dangerously low here.  Our assumption, the one we must
test in the chamber, is that this measure of gas exchange is a good
predicter inert gas exchange.  so far, all evidence points to it, but we
must still run many tests, before this goes from a theoretical concept, to a
basis for change in agency standards, to promote safety.  Neither you, nor I
, have indicated ANY change should occur until a great deal of testing is
done, to further develop these issues.

The next issue will be the helium, which saturates the fatty tissue
compartments much faster than did air.  More deco time will be needed for
extremely fat people because of these huge helium "sinks". Past tests on fat
rats, would need to show helium effects, for it to apply. On air, the obese
person may not be at as exponential a risk for DCS, as on helium, but this
will not be sufficient justification to dive deep on air.

Tom, I know you are compelled by concern for certification safety, just as I
am. I do not want to inflict emotional trauma on overweight people. I think
there is sufficient justification for the gas exchange issue in fit and
unfit divers to be explored at much greater length.  Hopefully, I'll be able
to tone down my less polititcally incorrect descriptiveness, and more heavy
people will take a second look at how they may improve their  chances of
alwasy enjoying accident free diving.
Regards,
Dan Volker

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