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Sierra Ledge Rat wrote:Ze's basically arguing that by hyperventilating and reducing pCO2 you can drive up the A-a gradient, which is what I argued against. The math shows that this effect is tiny.

The math and example I quoted from the textbook indicate the opposite. I have no motive in this, just going on what I've read.

I wonder how many top-notch alpinists in the world spend time hyperventilating. . .

dskoon wrote:I wonder how many top-notch alpinists in the world spend time hyperventilating. . .

well when at altitude, everyone has an increased ventilatory response (many call that hyperventilating, but it seems debatable)

I don't know what they do at sea level - again the original poster's question is what he could do at sea level to train for altitude. since eventually he will suffer from the side effects of (hyperventilation / increased ventilatory response), I merely speculate that 'practicing' that could reduce the side effects. it's pure speculation, but not absurd.

I wonder how much of this increased ventilatory response is actually a repsonse to hypoxemia. Usually our respiratory effort is driven primarily by pCO2, but at altitude I wonder if the paO2 can drop enough to stimulate a hypoxic response.

Anyone know the answer to this?

Actually the best way to voluntarily improve oxygenation at altitude is something that most of us do anyway unconsciously - it's called "auto-PEEPing" or "purse-lip breathing."

Basically you inhale normally, but then close your mouth slightly into an "O" shape and exhale against sllight resistence. It's sort of like blowing instead of exhaling. You do it naturally when you're huffing and puffing, so you probably don't need to practice it. Maybe just be aware of it and optimize it.

Exhaling against resistence increases alveolar pressure and thus increases arterial paO2, since:

paO2 = Total alveolar pressure x FiO2

The fraction of expired oxygen (FiO2) remains constant (21%), so increasing alveolar pressure increases paO2.

The increased pressure at the end of expiration (Positive End Expiratory Pressure, PEEP) also splints the alveoli open and so increases lung compliance (makes it easier to inhale). This latter effect is not really important in a normal lung, but can make a difference in a wet lung (HAPE) when the alveoli are flooded and the surfactant is diluted with exudate. Again, most people with HAPE purse-lip breath anyway to "get more air."

You'll probably be fine this time

Spend big $$ and get a system from these guys:
http://www.altitudecentre.com/

Sleep/exercise in a hypoxic environment. The U.S. military did some studies about effectiveness for soldiers on their way to Afghanistan but I couldn't find those results.

I think it's mainly genetics and if one experiences problems, then one has hit one's limits or has to train longer than the "average" high altitude regimern estimations.

Any of you have info in free diving with just a snorkel mask to increase one's capacity for using oxygen?

WileyCoyote wrote:I think it's mainly genetics and if one experiences problems, then one has hit one's limits or has to train longer than the "average" high altitude regimern estimations.

Any of you have info in free diving with just a snorkel mask to increase one's capacity for using oxygen?

Free diving is an anaerobic sport. It will increase your breath-holding and anaerobic capabilities, but won't help with high-altitude climbing.

Some of the altitude tent companies rent them on a short term basis.

I've been considering renting one for a couple of months before Hardrock, this summer.