At What Altitude Does Altitude Start Being a Problem?

Factual Questions
1

This question occured to me as I was hiking up and down large hills in Tennessee last week.

At what altitude does exertion start to be a problem? I don’t mean on the level of a medical emergency, but rather that one starts noticing less capacity for physical exertion?

5000 feet? 2500 feet? More? Less?

I suspect most of my discomfort was from being over 40 and not a fanatical athlete. Climbing 500 or more vertical feet is an effort, regardless of air density. At that, I did keep up with the 17 year old nephew and I wasn’t the one who needed a 4 hour nap after we returned to Grandma’s house.

2

I was in the best shape of my life when I spent some time in Denver. Right out of basic training, I was a lean mean fighting machine–that could not walk up a flight of steps without feeling winded. It got better over time, but I was never really comfortable out there. On the other hand, I could hit a softball considerably farther than I could at a more reasonable altitude…and everybody knows the chicks dig the long ball…:smiley:

3

Most folks won’t really notice anything until around 8,000’. Below that you will certainly notice something amiss if you are sprinting or working at the edge of your limits.

But for hiking, most folks don’t notice the lack of oxygen until 8,000+. That’s where people start really slowing down and getting altitude related headaches. Most won’t experience any symptoms of altitude sickness until 10,000 but it can definately occur lower.

I regularly hike above 5000’ in NH (I live at sea level) and there are no altitude problems.

4

My observation after living for 11 years in Colorado is that altitude affects different people different ways, and being young or in shape is no guarantee that you’ll not be affected.

I once was visited by a ~26 year old very much in shape flatlander. We went hiking in the mountains. He ended up with the worst altitude sickness I’d ever seen. He basically shut down and almost fell asleep during our descent. We had to force him to get up and keep going.

5

I figured you would have more experience with this than most being a pilot. I suspect it is a curve in which even altitudes above a few thousand feet will start to make exertion a little harder and it just gets harder from there. Some of the supplemental oxygen requirements for aircraft start as low as 8000 feet and become mandatory at 15000 feet.. However, I have read that lower oxygen tolerance varies a lot by individual.

6

Yeah I’d agree with the previous.

after about 5000 you start to notice a little weakness when working hard, but I’ve never seen about really get sick from it.

Most ski areas are 8000-10000, and most lowlanders notice it pretty strongly skiing or hiking, and some bad altitude sickness, even fatal, isn’t all that uncommon.

Top of Pike’s peak, 14000 a lot of people get light headed and wierd even standing around, and walking up the mountains to that hight seems to effect everybody a fair amount.

I’ve never been higher than that.

P.S. any of you other Coloradoans pissed off that stupid Mt. Whitney is the tallest mountain in the lower 48? It seems like a load of crap to me. I think we should all head out to California with shovels and dynamite to take about 70 feet off that sucker and put Mt. Elbert on top of the list.

7

:smack: That was a bad train of thought, let me try again. At 8000-10000, fairly bad altitude sickness is not uncommon. Death from it is very rare though

8

Well, I get down below about 2000 feet and notice that they have WAY too much air - it’s like breathing soup. Good lord people, with all that air and the humidity, how do you get anything done?
Going the other way, a 5000 foot increase will slow me down but a 2000 doesn’t… Somewhere in the middle apparently. Not very helpful, I know, but there you go.

[soapbox]I’ve seen altitude sickness drop some pretty healthy dudes, which the OP didn’t ask about, but going from sea level to 11,000 in one day and expecting to ski/hike/climb/etc. is not a good idea.[/soapbox]

wolfman, can we each take a rock to the top of Elbert instead of going to California?

9

Going to Denver has never bothered me. However, I notice a distinct difference in Colorado Springs (elevation 6,035 feet.)

10

insert random “focus on the family” joke here

11

Altitude sickness varies widely from person to person, and has little or nothing to do with fitness. One can acclimate (which is why in the Himalaya they spend time at the lower camps for a while).

Even climbing the 14ers in CA or CO, if one just stays overnight at 10,000 ft or so, it will help. Some people really suffer altitude sickness at as low as 5K ft, others (and I’m one of the lucky ones) never seem o be affected much other than a bit of light-headedness. If I were not already a bit light-headed, I’d probably not be climbing mountains all the time. :smiley:

For fit hikers and climbers, effects are usually not noticeable until above 10K feet. If you are not prone to sickness, it’s just the lack of oxygen that causes you problems, and you just go slower.

There are two very severe types of altitude sickness, HACE (High Altitude Cerebral Edema) and HAPE (High Altitude Pulmonary Edema). The former gives you splitting headaches and can kill ya’ while the latter will make you cough your lungs out, almost, and you will actually drown in the fluid. That will kill too. Better to avoid these if you are prone to these.

Seriously, the ONLY cure for either of these conditions, if they start, to get the hell down as far and as fast as you can. The trouble is, the high altitude also affects your judgment, so many people start suffering these ill effects but don’t realize they should descend quickly. That is why you should always have at least one buddy if climbing at altitude.

The Air Force started studying this during WWII and there has been a vast amount of study of it since. One of the CA universities has a lab part way up 14K ft White Mountains in the High Sierra and another hut on top where they study it, and other studies go on in Europe and elsewhere.

The result of all this study to try to determine who will or won’t get altitude sickness is, oddly enough, I]nada.* They still have no idea why some people get it and others don’t. Highly fit marathoners can get it, and couch potatoes may not (providing they can get up there some easy way).

My wife begins getting headaches and dizziness at Flagstaff, AZ which is only 7,000 ft, while I can stagger all the way to 14,599 (highest have made yet, on Mt Whitney) without any sickness at all. In fact, I was 72 years old when I did that mountain, so neither age nor stupidity affects who gets it either, obviously.

Well, it does tend to keep the pussies off our mountains. :smiley:

12

Fitness and health has absolutely nothing to do with altitude sickness. There is no corellation. Very fit people can get altitude sickness at as low as 8,000’. People not in shape can function fine over 12,000’. It seems to be luck of the genetic draw as to whether you will do well at altitude.

You can spend time acclimatizing to lessen the effects of sudden changes in altitude. Spending nights progressively higher will allow most people to function well above 10,000’ but some folks simply cannot operate at altitude. They have to descend to get rid of the symptoms. If you are acclimatized and fit, you can do more than someone who is acclimatized and not fit, but the symptoms of altitude sickness aren’t changed. Running out of breath isn’t the same as headaches, vomitting, collapse.

There is less oxygen at 5000, and it certainly is noticable when you are under heavy exertion. Pro athletes can notice it playing football, soccer, and basketball in Denver, probably less so with baseball. Most folks will notice it when climbing stairs quickly or playing hard, but it quickly goes away. Spend a night or two in Denver and the affect will disappear or be greatly reduced. Your body will start producing more red blood cells quickly but it takes a few days, up to two weeks to really adjust fully.

13

Yes, but there’s a large difference between sitting in a cockpit versus climbing a small mountain.

Between the flying and the asthma perhaps I am more aware of the question than most other folks. I try to pay very close attention to what my lungs are doing from a sense of self-preservation. I was breathing pretty hard during the uphill parts of the hike, but not wheezing, not dizzy, no black floaty spots in the vision… I suspect climbing up a 500 foot staircase in the Chicago area where I live would have been an equal effort.

When we visited Cade’s Cove, North Carolina about 10 years ago I noticed I got winded very quickly - but Cade’s is around 6,000 feet so that’s not entirely surprising.

Actually, for night flying supplemental oxygen suggestions start as low as 5,000 MSL. Although the major cognitive functions do not appear impaired, extra oxygen apparently noticably improves night vision, particularly in older pilots and smokers. Not required, mind you, just suggested.

Clearly, this will vary by individual as well by general fitness, age, health issues, etc. And activity level. Many answers here seem to concentrate on altitude sickness, which as I thought I mentioned in the OP, wasn’t my intention. I’m curious as to when people notice an effect - not necessarially illness/headache. Of course, I’m sure plenty of tourists don’t notice the ill effects until they’re ready to pass out, some people are like that.

I think I’m aware of breathing a little harder/getting winded more quickly even as low at 2500 to 3000 feet, but it’s a very slight change and I could be fooling myself. Definitely some difference around 4000-5000, enough that I’d probably be careful to pace myself but it wouldn’t stop me from going on a hike or doing normal stuff. Just wondering if anyone else noticed something of the sort that low.

14

Damn, KlondikeGeoff, you beat me to the submit button. Curses!

I had no trouble in CO or CA with altitude sickness for the 14’ers. In Nepal at 18K I had a nasty headache but that was about it. But the lack of oxygen up there is a killer. I didn’t really notice it much at 14K but at 18K it felt like walking in a fog. It took us 6 attempts to get a successful two-person hackysack. :smack:

15

I always wondered about this in airplanes. Supplemental oxygen is required above 15,000 feet, yet people have climbed Everest (20,035 feet) without the use of oxygen. I know that without acclimatation you can’t stay at altitude, and certainly the pilots need it, but how much would my health suffer in the five minutes it would take to descend from 30,000 feet to say, 10,000 feet?

I assume in a depressurization situation the pilot would go into an emergency dive at the maximum descent rate, which, for a passenger jet is what, 4000 feet per minute or so? It’s going to be different for every aircraft, but I seem to remember it’s somewhere around there.

16

Oh yeah, if you’re sitting next to me in an airplane and something happens, don’t assume I’m curious enough to make the experiment. I’ll probably have my oxygen mask and yours both. Fair warning.

17

True. And altitude sickness of one sort of another is a factor in the mountain’s death toll which, I believe, still averages one climber in seven. A few mountaineers have managed it, but most of 'em - even most Sherpas - still use supplemental O2. Only a small minority of people have won the genetic lottery in the sense of having a cardio-pulmonary system up to the task of climbing Mt. Everest without extra O2.

Current standard for passenger jets is a cabin pressure equivalent to 8000 MSL, but the newer designs are shooting for 5000 MSL for greater passenger comfort. After all, not every passenger is in peak health or condition, and as pointed out previously, a certain percentage of people will feel effects sooner than others.

IIRC, a pressurized emergency descent for a passenger jet is around 1000 feet per minute. In a decompression emergency, though, I think it might well be faster. Certainly, the airplane is capable of descending very rapidly but there are issues about control, airspeed, and safely pulling out of the dive to consider. If we’re lucky, one of the Dope’s airline pilots might check in and enlighten us.

Assuming five minutes and descending from 30,000 to 10,000 feet… well, you’d be unconcious part of the trip. The cabin would probably get cold. So… you’d probably wake up going :confused: , shivering, with a headache. It’s possible to suffer from a variant of the bends under such circumstances, but it’s a crap shoot who will actually show symptoms (although such things as scuba diving in the recent past will vastly increase your odds of such). However, by the time you reach 10,000 feet symptoms such as joint pain should have gone away and, as already pointed out, you’d be unconcious for most of it. It’s possible some folks might blow out an eardrum in a decompression, or suffer sinus problems (this can occur in skydivers and pilots going from roughly sea level to 10,000 feet, which is why aviation activities are not recommend with ear infections and sinus problems). It’s possible that someone in ill health or someone very frail may die from the stress of such an event, but most people would probably emerge with no permanent ill effects.

It takes hours for that sort of altitude change to kill, not minutes.

18

Right, man, you’re getting close to THE DEATH ZONE!

I envy you getting to Nepal, it must have been worth the headaches, eh? The thing I like about trekking poles is that up there you can stop, lean on the poles and pretend you’re admiring the scenery while you are actually gasping for breath. :smiley:

19

wolfman, I agrees with ya about Mt. Elbert. Mt. Whitney may be taller, but for sheer mass, nothing beats the Colorado Rocky Mountains!

As to the general discussion:

When my ex and I moved to Durango (alt around 6500 ft.) from California in 1991, we were soon followed by his parents, who stayed one year, decided they didn’t like it, and moved back. :rolleyes: His sister came out from Lancaster (CA) to help them move. We told her to take it easy for a day or so, before she started in packing. She didn’t listen, and ended up in the ER needing oxygen and IV fluids. :smack: Fine. Don’t listen to us, dumbass.

20

For me, about ten feet. I may have been the only air assault qualified infantryman in existance who is afraid of heights. I used to jump out of helicopters rapelling down 90 plus feet. Now I will not get on a single story roof. Back then there was peer pressure, to day I can hire someone to clean out the gutters…