Blood, sweat and frozen tears – your body’s response to high altitude

“Every Alpinist who climbs 8,000-meter peaks searches for ways to prepare the body so that it will adjust to the variables. The environment at extreme altitudes is as alien as outer space; the dynamics play out in ways that we cannot fully understand. A mountaineer can only hope that a commitment to constant training will prop up his ambitions to explore the earth’s highest reaches.” Anatoli Boukreev – Russian alpinist

We still have very little understanding of the effects of altitude on a human body but without a doubt it has major impact on us physically. These effects start to occur at around 3000 meters above sea level. All 7 Summits are above 4500 m so we definitly need to take into account that this will be something we need to deal with a lot next year. Let’s have a look at a few important facts of altitude and physiology.

To do a given workload we need to provide the same amount of oxigen to our muscles at high altitude as we do at sea level. But the VO2Max (Maximum rate at which the heart, lungs, and muscles can effectively use oxygen during exercise) of an acclimatized climber at 8800 m (Everest’s Summit) is 20% of his VO2max at sea level. Maximum attainable hart rate and blood volume is reduced dramatically at high altitude. This translates directly to how fast you can move, At any given task, whether it is packing a tent or ascending a snow ridge, a climber at 8,000 meters is 80% slower. This fact clears out the importance of training hard to increase VO2max before going for a high altitude expedition.

Even with the largest VO2max imaginable, it is impossible to climb up these summits in one straight pace. Your body needs to adapt to new altitudes, acclimatize. There are two ways of acclimitization;

  • Increasing the efficiency with wich those muscles use oxygen
  • Increasing the ability to deliver oxygen to the muscles

The first thing depends on the training you’ve done before you set out on the expedition.
The second thing happens naturally, it’s simply a matter of time before your body starts to build up more hemoglobin to be able to transport the oxygen to the cells. Let me tell you how this works…

Within hours of getting to high altitude your respiratory rate goes up, your hart starts to pump faster, blood pressure goes up and your bone marrow starts to make new red blood cells. These red blood cells can be seen as the taxi’s in the blood which transport oxygen molecules to the cells. These new minted taxi’s take 7 to ten days to mature and become ready to do their job.
You simply need to wait before you can continue the ascent. One of the most common mistakes a firts-time altitude climber make is expecting their bodies, once acclimatized,  to feel as strong at height as down low. This never happens.

What is interesting is what happens to the heart at altitude, it seems fairly contradictory. Logic seems to indicate that due to less available oxygen your heart rate would be higher than it would be at lower altitude. But fact is, your heart rate decreases at altitude. It appears to limit itself, presumably to keep it from damaging itself. A reduced maximum heart rate reduces the volume of blood pumped to your cell each minute which results in a reduction of power capacity. To give you a bit of an idea, the pace a climber self-selects  at 6000 meters is around 50-75 % of their VO2max.

Climb high, sleep low strategy

This strategy was first been proposed to mountaineers by Dr. Houston. It means that you can climb as high as you want to give your body the altitude stimulus, but the average elevation gain of each night shouldn’t be over 305 meters.  Gradually you can work your way up the mountain to higher and higher altitudes. Doing this, you acclimate much faster than just staying in one spot for several days.

Spend one night high, descent low, the Sovjet System

The Sovjet system works the other way around. It seems to express something many climbers experience, the body cannot easlily do the work of acclimating while remaining up high. The night spent high provides the stress. These climbers carried a light kit to spend the night and then return all the way back to base camp the next morning to rest. The recovery period at base camp allows better recovery at rest, which provides the energy for theses physiological changes.

Do it yourself!

The trickiest part of acclimating is having the right strategy. Think this trough before you set of. The very best advise is to GO SLOW!!
In upcoming blogs I will tell you all about mountain sickness and the causes of it. Something you definitily want to take very serious because very often mountainsickness means game over.
If you are not completely sure about your own strategy of ascending a high altitude peak, feel free to ask your questions in the comments below or send me an email with your schedule to; [email protected]

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1 comment

Stefan van Gestel 4 September 2019 at 01:47

Dag Judith,

Interessante blog. Eenmaal geacclimatiseerd, hoe lang duurt het voordat de extra rode bloedcellen in het systeem blijven?

Wij zijn namelijk momenteel aan het acclimatiseren gedurende de Annapurna trek en mijn companion doet eind september mee aan de marathon van Berlijn en vraagt dit zich af. Ook rest de vraag of het überhaupt significant verschil uitmaakt voor hem.

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