Altitude Effect of hiking to the top of Half Dome



Theories, just theories.

The LA Times recently posted an article about altitude and said the following:

QUOTE  Anyone who has climbed Half Dome or played baseball in Colorado knows that high elevation causes shortness of breath and other symptoms of “hypobaric hypoxia,” due to low pressure and oxygen Good article, but having hiked Yosemite’s Half Dome 38 times and written the only guide book on it, I disagree that being at the top of Half Dome rebated to your statement that it’s “high elevation causes shortness of breath and other symptoms of “hypobaric hypoxia,” due to low pressure and oxygen.  UNQUOTE 

What do YOU think about this?

I’m no expert or Nobel prize winner….but I think neither is the author. My take: Half Dome is only 8,842 feet high – not enough to cause those symptoms. Aircraft are pressurized to 8,000 feet. Tuolumne Meadows to the north of the Valley is also at about 8,000 feet. People don’t keel over hypobaric hypoxia. While I agree that each person is different and altitude sickness is individualized and people can react differently, you need to be much higher – say 11,000 ft and higher to experience “hypobaric hypoxia.” Even then you may get the classic “altitude sickness” symptoms – headache and nausea and diarrhea. Ask my brother. He got these at 12,000′ as we went up Mt Whitney. I felt fine the whole time.

Toss your 2 cents in and let’s hear your opinion and/or experience.


Unrelated thought worth quoting: “I want to take you higher.” – Sly and the Family Stone

MrHalfDome™ – Rick One Best Hike: Yosemite’s Half Dome

About Mr Half Dome - Rick Deutsch

Mr Half Dome. Has written the only half dome hiking guide, One Best Hike: Yosemite's Half Dome. Has hiked it 31 times to day. Lives in San Jose, CA Available for presentations. Carpe Diem Experience, LLC
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17 Responses to Altitude Effect of hiking to the top of Half Dome

  1. John says:

    Nick’s comment above from 2013 is incredibly like my experience today 9/27/17 at HD in Yosemite up the Mist Trail about .5 miles from the HD summit.

    My girlfriend and I flew in the Saturday before from Jax FL and are both avid athletes in great condition. I am 38 and she is 33.

    We hiked the Upper Yosemite Falls Trail including the extra 1.8 miles to the Yosemite Rim on Sunday the day after getting in, and although it was an as- kicker of a hike, I felt fine. The next day we hiked 8 miles on the Cathedral Lakes Trail in Tuolumne which is around 8000 feet give or take from start to finish. No issues on this hike either.

    Did an easy day yesterday with Sentinel Dome and hanging around the mountain house, and we planned on hiking the Mist Trail the next day (2 unsuccessful HD lottery attempts). I had a couple beers and didn’t sleep well the night before.

    Began Mist Trail at 7am and we both felt great and a couple was nice enough to give us their HD permits and we had enough food and water (and filter for purifying extra water), so decided to take a shot at a HD summit.

    Felt great through both falls and past Little Yosemite campground and then about halfway through the forest on the way to subdome I started feeling something like I’ve never felt before and I’ve done tris and long AT hikes and never before have I felt the disorientation, dizziness, feeling of a fever and a fever’s chills and inability to stay warm, and diminishing cognitive abilities like I did just before the ascent of Subdome.

    I knew something was wrong. I would look at my Garmin and not understand the simple data it was showing and stumbled as I walked. Wasn’t lack of nutrition or hydration and some electrolyte tabs I had did nothing. The higher we hiked, the worse I felt.

    I contemplated just pushing on since we were so close, and then even hiking to subdome to ask the ranger for medical aid, but like Nick said above, I’m so glad I made the decision to turn around and head down, which after about an hour and a half or so brought great relief. something really wrong was happening and I could’ve put others in danger and myself had I continued to the cables.

    Still a great 16.25 mile hike and lesson learned with altitude and trusting your body.

    • Thanks for sharing. You did a lot of stressful hikes so close to going up Half Dome. You should have been acclimated. I wonder if the build-up had an effect. How about the smoke? Think that you were not getting enough good air? Wise decision. The rock will be there for you next year.

      • John says:

        Good questions Rick. Really not sure what happened. Thought we planned it safe acclimatizing and doing some solid warm ups at varying altitudes, and as others have pointed out HD isn’t that high compared to other summits in the States or the world. The smoke wasn’t an issue yesterday and I guess it just was a factor of not taking our time and trying to summit too fast, but disapppointed it happened. But you nailed it—there will be another day. We’ll be back for sure.

  2. Diane says:

    I hiked Half Dome a few years ago. The only problem I had with the altitude was it triggered my asthma. I was winded frequently so had to stop frequently to normalize my breathing. We started out from Glacier Point so it was a long but beautiful hike.

  3. Rod Braithwaite says:

    I live at sea level and I hiked HD last weekend (July 6/14) after two nights of only 4 hours sleep each. Spent a few weeks on treadmills and local hills to prepare, so OK for conditioning. Started to feel a bit queasy at the top of Nevada fall, short of breath and vomiting began at about 7500 feet. Couldn’t keep water down much after that. I have had AMS in Peru and this felt very similar, but might have been worsened by the lack of sleep.

    • Rod – I do think your body stressed under the heavy load it was taking after nil sleep. 9,000 feet is at the very low end of altitude sickness…but those are the symptoms.

      Cuzco, Peru, is at 11,000 feet. Most do get woozy after landing. Ahhh, coco tea solves that! Folks: Machu Picchu is lower at about 9,000 ft.

  4. Nick says:

    Last summer i hiked up last summer and felt great until about .5 miles from the cable . It started out that i needed to take more and more breaks, but by the time i got to the cables i had to take about a two minute break after each three steps. I am 27, in good physical shape, trained for the hike and drank plenty of water. I have never felt anything like it in my life and my girlfriend was fine. I tried taking a 30 minute break before the cables, but since my breathing wasn’t getting any better i figured it was best for my safety and more importantly the safety of others not to try the cables. It was a tough decision but i knew it was the right one. On the way down with every step i could feel myself regaining strength and by the time we got back to the car i felt normal again. I know it wasn’t my fitness level. I will say I’ve lived at sea level my whole life, but i think the real cause is a combination of stopping at death valley the day before (just poor judgement) on our road trip and just genetics, as my girlfriend was fine. I think when i get back out there i will try to camp at a higher elevation and again assess how i feel at the cables, but as for this time i know it was the right thing to do to turn around.

    • Nick,

      This is a great comment. A real world experience. Even light dizziness and an unsteady feeling could indeed be caused by the altitude. Your possible reasons could be dead on. It’s a roll of the dice who gets affected. I take it real easy the week before and taper down my training. I am in bed at 9 pm the pre-night. A couple hundred a day go up the HD cables with no issue. Good luck on your next hike.

      Thanks for sharing.


  5. Ewing Hatfield says:

    I have done halfdome a few times now. Twice I drove up the morning of my hike, and on each of these hikes the altitude kicked my butt. This most recent trip I was able to camp at upper pines and acclimate the day before my hike. The next day My hike was effortless. To me, acclimation to altitude and being in shape are keys.

  6. Jessica N. says:

    When my parents hiked Half Dome two summers ago, they said they could tell that there was less oxygen. When I went (same summer, but a separate trip), it took me until 9000′ (en route to Cloud’s Rest) to notice the lack of oxygen. It could be a) because I’m younger and in better shape, b) I wasn’t paying as much attention to the air “thickness”, or c) I spent a night at 6000′ before climbing Half Dome, then spent two more nights at 6000′ before climbing Cloud’s Rest (whereas my parents did a day hike to Half Dome from the Valley). Probably a combination of all three factors.

    Do most Half Dome hikers tend to notice the thinner air?

    • I think all 3.

      To be honest and not rude, I’ve never seen anyone with AMS on the HD hike. The FEW people that I see complaining seem to be in bad shape – no training. Just tired – not from altitude. But that’s just my observation.

      I don’t feel any difference. And I live at Sea level…in the 10th largest USA city: San Jose-by-the-sea.

  7. Maureen L says:

    Researchers have found that pressurizing aircraft cabins to 6,000 feet would increase passenger and crew comfort.

    There’s a nice summary of the New England Journal of Medicine article published July 5, 2007 here:

    “…acute mountain sickness, which can involve headache, nausea and vomiting, can occur at altitudes of 6,500 feet and higher.”

    • I’m sure that if planes could be pressurized to sea level, people would feel more comfortable. But fuselage structures need to be light so the plane can travel further.

      I agree that everyone is different and things can occur…But you can also drown in 2 inches of water…but nobody does. I’m curious if there are any real world personal stories anyone has.

      • Maureen L says:

        The link I posted discusses an experiment in which people were placed in various levels of pressurization and their responses noted.

        There are recommendations to pressurize to 6,000 ft instead of 8,000 ft.

        My own suspicion is that the nausea folks I’ve met on the top of Half Dome had dehydration and electrolytes out of balance.

        • When I was in the Air Force I went through the altitude chamber class. We were hooked up to Oxygen and they slowly lowered the pressure to simulate flying way up there. A sergeant sat across from me and I would have me do simple math problems on paper. No issues….then I could not multiply very well….then I could not even add one digit numbers…next step is passing out…then they are there to bring me back.

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