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High altitude illness on summit of aconcagua

The Hypoxia Hurt Game

Your head hurts, you’re slight­ly nau­seous, each step you take injects pain into every cell of your body, and you have a hard time wran­gling the moti­va­tion to eat. Hun­gover? No. Just climb­ing at ele­va­tion. Wel­come to the hypox­ia hurt game.

As moun­tain ath­letes, the ele­va­tions that we play in affect our bod­ies and minds in many ways. If you’re like us, you want get the most out of your time trekking or climb­ing in the moun­tains, it’s impor­tant to under­stand the phys­i­o­log­i­cal changes that your body is endur­ing at ele­va­tion, and how they man­i­fest for you. 

How well you do at high alti­tudes depends on many vari­ables to be sure. You can train for months in advance of your trip and be in the best shape of your life, but if you ignore the poten­tial impacts of high alti­tude ill­ness your hard work may all be for naught. Prepar­ing for a high alti­tude trek or climb includes train­ing, get­ting the essen­tial equip­ment, some men­tal work, and under­stand­ing what your nutri­tion­al needs will be. But, the first and fore­most way to pre­vent ill­ness up high on your climb is knowledge.

How high is high?

Alti­tudes over 9,000 feet (2,743 M) are con­sid­ered high. This means whether you are on Mount Bak­er, Kil­i­man­jaro, or Aconcagua, you will be impact­ed no mat­ter who you are and how well you do up high. As ele­va­tion increas­es, atmos­pher­ic pres­sure decreas­es. Low­er pres­sure allows the oxy­gen mol­e­cules in air to spread out. This means that each of your inhala­tions at alti­tude con­tain few­er oxy­gen mol­e­cules. At the top of Ever­est (29,035 ft / 8848 M) the par­tial pres­sure of oxy­gen is one-third that of sea-lev­el. If you were mag­i­cal­ly deposit­ed at the top of Ever­est with­out pri­or acclima­ti­za­tion you would lose con­scious­ness with­in min­utes and you would die.

17 April17 Icefall3 FB
Everest summit with Mountain Madness
oxygen on mount everest with mountain madness


There soon becomes a lot of activ­i­ty in your body as you arrive at high­er alti­tudes. The first reac­tion is your body accli­mates to low­er pres­sure and less oxy­gen with both acute and longer-term changes. Ini­tial­ly, your body, won­der­ing where all the oxy­gen has gone, responds by increas­ing your res­pi­ra­to­ry and heart rates to increase oxy­gen deliv­ery to tis­sues. Then, your kid­neys start pro­duc­ing bicar­bon­ate and increas­ing urine pro­duc­tion to keep your pH neu­tral. After a cou­ple of days at a new ele­va­tion your heart and res­pi­ra­to­ry rates start to slow down as your pH returns clos­er to nor­mal. Your body also responds by increas­ing a hor­mone called ery­thro­poi­etin which in turn increas­es the pro­duc­tion of oxy­gen-car­ry­ing red blood cells. Increased ery­thro­poi­etin pro­duc­tion starts with­in min­utes of arriv­ing at high alti­tude but takes 2 – 3 weeks to complete.

How to pre­vent illness

If you’ve ever rushed the acclima­ti­za­tion process, like a two-day ascent of Mount Rainier, or dri­ven to the top of Pike’s Peak, you’re famil­iar with the headache that marks the onset of Acute Moun­tain Sick­ness (AMS). Oth­er alti­tude-relat­ed ill­ness such as High Alti­tude Pul­monary Ede­ma (HAPE), High Alti­tude Cere­bral Ede­ma (HACE) and High-Alti­tude Flat­u­lence Expul­sions (HAFE) can also occur; the for­mer two can be dead­ly, while the lat­ter only threat­ens the wel­fare of your tent mate and lead you to end up sleep­ing out­side. These risks can be min­i­mized by fol­low­ing a prop­er acclima­ti­za­tion strat­e­gy, chang­ing dietary habits, and in some cas­es by using medications.

If you are com­ing from low­er ele­va­tions, or even sea lev­el, those aren’t points against you in the game of high alti­tude moun­taineer­ing or trekking, it’s just some­thing that needs to be strate­gi­cal­ly han­dled with each new ele­va­tion reached. You don’t need the cen­turies old genet­ic adap­ta­tions to alti­tude of a Sher­pa or the Andean Quechua, just some basic things will go a long ways in help­ing you reach your goal.

Cho Oyu summit climb with Mountain Madness
Kili Summit Oct2010
western breach on Kilimanjaro on the way to the summit

As moun­tain ath­letes who endeav­or to climb high and feel as strong as pos­si­ble, the best way to work with the changes that alti­tude caus­es is to accli­ma­tize. Prac­ti­cal­ly, this means ascend­ing to a new high point then return­ing the same day to sleep at a low­er ele­va­tion. This climb high, sleep low approach allows your body to slow­ly adapt to the stress of per­form­ing in an oxy­gen deprived environment.

So, what’s a moun­tain ath­lete to do?

  • If you’re join­ing a Moun­tain Mad­ness trip, please read the sec­tion of high alti­tude ill­ness in your depar­ture info we send you; otherwise,
  • Plan acclima­ti­za­tion into your schedule
  • Reduce as much stress on your body as pos­si­ble. Stay hydrat­ed, rest, eat well
  • Com­mu­ni­cate how you’re feel­ing to your guide or teammates
  • Lis­ten to your body — there are times when you have to push through the hurt and oth­ers when it’s bet­ter to take a time out; it’s ok to take a break now and then 

Some sol­id resources

Train­ing by your­self or with a part­ner is fine, get a pro­gram dialed and stick to it. But, if you hire a train­er it’s worth con­sid­er­ing find­ing some­one that has some knowl­edge of high alti­tude climb­ing and trekking and what your body goes through. Alpine Ath­let­ics own­er Lisa Thomp­son, who has climbed the Sev­en Sum­mits and K2, has pro­grams that train you, gives you advice on equip­ment and nutri­tion, and that pro­vide invalu­able insights from some­one that has played the hurt game and over­came the chal­lenges of high altitude.

A cou­ple of go to books to get you schooled and intrigued at the same time include Going High­er and Train­ing for the New Alpin­ism.

Con­trib­u­tors: Dr. Tracee Met­calfe, Lisa Thomp­son/​Alpine Ath­let­ics, and Mark Gunlogson