/ Do you measure your SpO2 when acclimatising?

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Getoiu 11 Aug 2019

Do you measure the oxygen saturation in your body while acclimatizing and if yes, then what percentage should be a good sign that one is not properly acclimatized? At what percentage do you feel comfortable to climb again? 

I presume no one's acclimatizing to 95% when above 5000+ meters

Post edited at 01:05
summo 11 Aug 2019
In reply to Getoiu:

I think it's a bit over analytical. I've known folk with poor stats go like machines on the mountain and others with apparent good numbers feel dire and decide to come off the hill. It's also no indication of recovery between hills to know when to go again. 

You can't analyse fitness at altitude with a single measurement. 

althesin 11 Aug 2019
In reply to summo:

Not an expert, but measuring your bicarb would let you know when you'd done most of your respiratory/renal compensation for altitude, oh and haematocrit, that would be useful too.

Saturations would be pretty low at any kind of altitude, figures of about 50% on Everest in acclimatised conscious subjects recorded.

ben b 11 Aug 2019
In reply to Getoiu:

I'd put it in the "actively unhelpful" category; easy to measure, no real relevance to risk. 

It's kind of difficult to explain but SpO2 measures the percentage of your haemoglobin that is saturated with oxygen. Acclimatisation increases the amount of haemoglobin, so more oxygen is carried per unit of blood. But the saturation might not change that much. My SpO2 at sea level is 97%, but if you give me a blood transfusion (or a shedload of Epo) it will still be 97%. However more blood equals more oxygen carriage per unit volume.

There are changes over time in SpO2 at altitude but they are complex and at times a little contradictory. I think performance at altitude is about many factors (including food, rest, sleep) and SpO2 is a minor player.


In reply to Getoiu:

The signs of not being properly acclimatised are more obvious than any number on a gizmo, not sure you need a gizmo to recognise being poorly acclimatised.

kenr 11 Aug 2019

The other big problem with measuring oxygen saturation is that it reinforces the mis-conception that acclimatization and athletic performance at altitude is all about Oxygen.

Ignores Carbon Dioxide, which is physiologically very important for human symptoms and performance.

. . . (also ignores Nitrogen, but that's _not_ so relevant to human physiology at altitude -- but very important for certain plants).

Note that if acclimatization were simply only about Oxygen, then one-week holidays from London to the Alps would not work -- because it requires two weeks to significantly increase red blood cells and hematocrit.


Post edited at 17:23
Stichtplate 11 Aug 2019
In reply to Getoiu:

The vast majority of pulse oximeters are designed to work on fingers. If the subject is cold the body will constrict blood flow to the peripheries and produce a low spo2 reading. It can be hard to ensure accurate readings in typical mountain conditions.

SouthernSteve 11 Aug 2019
In reply to Stichtplate:

I notice Garmin have added this to their latest 'Fenix' watches - so wrist based. Apparently it 

'allows you to assess your physical condition, formulate fitness goals and decide on an appropriate training intensity, all in real time'

Sounds a bit far fetched to me. More like a different kind of altimeter. Might be handy on budget flights to argue for a bit more cabin pressure though!

summo 11 Aug 2019
In reply to ben b:

All that maybe true, but on a multi peak trip in the alps, or say south America you'd rely on previous experience and weather windows to decide your plans not spo2, midichlorian levels or anything else.

If you can hold your breath while you squat taking a dump in a stinking French hut toilet and not pass out, I'd say you are ready for another peak! 

Post edited at 20:09
Denzil 11 Aug 2019
In reply to Getoiu:

Page 12 of this booklet includes an example of the sats on a trekker in the Himalayas


as other people have stated, a simple sats measurement doesn’t really tell you how well you’re acclimatising.

Ash Routen 13 Aug 2019
In reply to Getoiu:

Guides are starting to use SpO2 on Everest. I wrote about this here:


And Dr Leo Montejo has written about their use at the bottom of this piece:


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