Francois, I can't really help you here, but I would suggest that you desguise this post as a PC vs RC thread and try to get Andrew Coggan to get involved. Did you post this on the Gordo Forum?

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"Yeah, no one likes a smartass, but we all like stars" - Thom Yorke


smartasscoach.tri-oeiras.com

haaaa...I recognize here the smartasscoach we all know :-)
I though AC would see that...maybe best to post on G's indeed.

People with higher VO2max values will tend to desaturate more at a given altitude. One theory as to why this occurs is the blood transit time through the lungs is shorter. At higher altitudes (and hence lower partial pressures of Oxygen), the blood has less time to grab a full load of oxygen.

This is why people with high VO2max values tend to lose relatively more performance at altitude. All this being said, this is still a trend, there are people with very high VO2max values that do not desaturate, and do quite well at altitude. Nothing is ever simple.

Scott Martin

you just need to move to Cali :)

Francois - shoot me an email at mike@d3multisport.com and I will get you the email of Dr. Randy Wilbur, who does extensive studies in this area at the USOC in CO Springs. I think he will be answer your question.

Mike

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Mike Ricci
2017 USAT World Team Coach
USAT National Coach of the Year
Coaching Triathletes since 1992.

Are you 92% at rest? I like smartin's explanation, but I've only heard of elite athletes desaturating (a little bit) at high efforts when cardiac output is very high.

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So, I was measured at 81mlO2/min/kg of Vo2max
at sea level (4' step tests, direct measurement) and
was measured at 72mlO2/min/kg here at 4500ft.

Would the O2 saturation change linearly with Vo2max.

to answer jhc, yes, I was measured at 92% at rest (yesterday).

81??? Damn Francois, I want to coach you! Now let's start by lowering that saddle :-)

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"Yeah, no one likes a smartass, but we all like stars" - Thom Yorke


smartasscoach.tri-oeiras.com

Maybe! Seriously the answer is not known. In your case it does for these 2 data points, but who know at other altitudes. Also, this effect is not universal. As I said before, the reasons why this occurs are not clear. Some people with very high VO2max values (you would certainly fit in that category) desaturate at altitude to a higher degree than others (this can be predicted by seeing if you desaturate at sea level with moderate/moderate high exertion, which is also something that people with higher VO2max's do more than people with lower VO2max's).

The practical aspect of this is alos not known... Can you acclimate to altitude and attenuate this effect? People's response to altitude acclimitization is also variable, what you are experiencing may or may not play a part in that.

Scott Martin

P.S. Just as an aside... Boosting your Hct by blood doping or EPO shouldn't change this effect. You would have more oxygen available, but unless you boosted your Hct to a point where blood viscosity became an issue (in which case desaturating would be the least of your worries), the blood transit time in the lungs would not change. There would be more overall oxygen available, and you would be faster, but would have the same oxy-hemoglobin saturation (or desaturation as the case may be..), and have the same relative loss of performance compared to sea level.

lowering the saddle? done...

we figured a seat too high with 56 chain ring was a good recipe for an achille tendinitis (which is what i have been dealing with for 2 weeks with a partially torn achille...in a much better shape now though)

Francois,

Not that this will help much - but I live at about 8000 feet. My sat is around 92-95% here. I also get to see about 1000 O2 sats/year (mostly people from sea level) and most people our age run between 90-95% at 8000 feet. 92% at 4500 feet seems a bit low. Running: 20-30 seconds/mile slower is what I see at 8000 feet (unless you are Meb or Deena - they don't seem to slow much) - biking is a wash (except climbing) from lower O2 vs. lower air resistance. Swimming is slower, too. I personally wouldn't expect to see nearly this effect at 4500 feet.....your pulmonologist should be able to figure it out. You could also consider getting an arterial blood draw to double check what your sat truly is (though that hurts) though the finger pulse ox's seem quite good these days. Good luck.

Sick all the time? Overtraining a possibility? You seem to put in monster miles.

Dave

actually saw some papers that suggest and average loss of 3% of Vo2max per 1500ft with some people losing much more, some not much.
I also noticed that on the bike, pace is the same as air is less dense and slower in the water too (about 2''/100yds at every intensity).
the measure was indeed taken with finger pulse ox.

Sickness seems clearly related to tons of allergies (including dust, which in El Paso is a MAJOR problem as that crap flies year round...). Even when not training, I still get sick, and unlike previous years, I have been very careful with recovery this year...still no luck though.