Perhaps the most frustrating aspect of altitude sickness is the randomness with which it can occur. The same hiker, who has no problem at 10,000 feet one year, might suffer at 8,000 feet the next. Some people go decades without symptoms and then, suddenly, begin to have problems.
The consensus is that most hikers will be fine until they get above 8,000 feet, but that’s no comfort on the JMT. Although the lowest point on the trail is 4,000 feet, after the first day or two you’ll be spending much of the first half of the trail above 9,000 feet (assuming you start at Happy Isles, the northern terminus). During the second half you’ll spend most of your time above 10,000 feet. There’s just no way to avoid the potential of altitude sickness.
There really isn’t a foolproof way to avoid it, either, although there are some common sense things you can do. These are roughly in the order of effectiveness (most effective, first):
Transition as slowly as possible. If you are coming from lower elevations, and if your schedule allows it, spend a couple of days in Yosemite Valley (4000 feet), then a couple days at Tuolumne (8600 feet), prior to starting your hike. While you are there resist the temptation to do a bunch of day hiking. The idea is to ease your body into handling the low pressure and thin air, not to shock the body into compliance.
Hike southbound. If you start in Yosemite Valley, you will postpone the highest part of the trail for a week or more, depending on your hiking speed. If you can hike ten-to-twelve miles a day, you should be able to end each day of the first week below 10,000 feet. On a few nights you should be able to get below 9,000 feet. That will be a tremendous help, because you are going to want to…
Sleep as low as possible. Himalayan adventurers have known for years that the best technique is to “climb-high, sleep-low.” Learn from them and plan your campsites accordingly.
Stay well hydrated. Start several days before you leave for the hike. Even on the days you are acclimating you are going to lose water much faster, through respiration, because of the high elevation. Once you get on the trail, DRINK! One of the worst things you can do is to delay your water intake because you don’t want to stop and purify water. Your goal should be for your urine to be almost clear. If it’s a nasty, dark yellow, you’re asking for trouble. Last, stay away from alcohol—few things will dehydrate you faster. The week before the hike and the first on the trail would be good times to abstain.
(Hydration is essential, but there is no reason to overdo it; this is the wrong time to over-hydrate and cause electrolyte problems.)
Eat and rest well. Once you’re on the trail you’ll quickly learn how interconnected the human body is. One ailment can exacerbate another very easily. For example, you might have a mild (and almost unnoticed) case of altitude sickness that can dramatically worsen if you don’t properly replace the calories you’re burning, and you don’t get a good night’s sleep. Think of yourself, while on the trail, as a professional athlete, and take care of your body accordingly.
Consider medication. The drug most often prescribed is acetazolamide, also known as Diamox. Most doctors recommend that you begin taking the medication one or more days prior to going above 8,000 feet. There is substantial difference of opinion regarding the dosage, and there are even some alternatives. Do some web searching and talk to a doctor who is familiar with elevation sickness. (One side-effect I can attest to from the Diamox is tingling hands. I know that sounds pretty benign, but I found it quite unpleasant.)
Next week, what to do if you start to exhibit symptoms on the trail.
Good hiking, Ray
A couple of things to add if you don’t mind:
1. Climb high, sleep low is not a cure-all, and it’s important to understand how this works. For instance, if you live at sea level, and were dropped off by helicopter to a 10k peak every day for 3 days, yet slept at sea level, you would not be acclimated to 10k. You really only truly acclimate to a level you sleep at. The most effective way to climb high and sleep low, is to sleep no higher than 1k above where you slept the previous night, yet climb higher during the day to give your lungs a workout. Mild to moderate exercise during the day is more effective than complete rest, because the very symptoms of breathlessness that you experience at higher altitude is what helps you acclimate. During the day, you can ascend more than 1k as long as you sleep no higher 1k above the previous night.
2. For every 3k in altitude gained, (at the point of where you are sleeping) you should have a rest day. Once again, a rest day is not total rest, but a day consisting of mild exertion.
3. Exertion level, in my personal experience, is of huge importance, and there are studies that bear this out. Hiking at high altitude going super fast, (where I was constantly out of breath) resulted in bad AMS, but doing the same trail and greatly slowing down my pace resulted in no symptoms at all. You often see this on Whitney. Marathon runners, used to pushing their bodies reaching trail camp in only 2 1/2 hours have trouble, while people who are greatly out of shape and take 6 hours to reach trail camp have no problem at all. My rule of thumb is to hike at a pace slow enough to enable me to hike for 3 hours without stopping to rest (a much more leisurely pace). This ensures you are not over taxing your body.
Following the three items above, I went from a person who experienced several episodes of pretty bad AMS above 10k (and thinking I would never get above 10k) to someone who can easily make the top of Whitney with no symptoms at all.
All great points. Thanks, Kathy!
Great article! And I wanted to chime in with an alternative to the prescription drug: Diamox that you mention. Acli-Mate Mountain Sport Drinks have a great track record helping people avoid altitude sickness. We receive testimonials from a majority of our customers who have previously experienced altitude sickness and then found Acli-Mate which has alleviated symptoms for them. Acli-Mate comes in a powder you mix with water and has all natural ingredients. Great for kids and adults – any mountain visitor or athlete. We have testimonials and more information on our website; http://www.acli-mate.com Happy hiking!
Sounds interesting. I may give it a try on my next JMT hike. Thanks!
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I would like to add that there is a product from Royal Body Care called Microhydrin which has been proven effective in oxygenating the blood. It is a powerful anti-oxidant that we have used for years. Personally I wouldn’t hike without it.
Aloha, Diane
Interesting, Diane. Thanks for posting this.
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