I don’t know if I would consider it “grave harm”, but you will DEFINITELY feel the difference - as in gasping for air. You can certainly try to run as much as you do at sea level, but I assure you, you will feel the effects until you get acclimated. A change of even just a couple 1000 feet in elevation can be felt.
How much of a difference it makes will vary from person to person, but it will absolutely, without question, make a difference. I don’t think it’s possible to come to grave harm, but you will definitely get tired faster.
For me, whenever I go back East and let myself get de-acclimated, when I come back it always feels like all the hills are steeper.
Either you won’t be able to go as fast, or you won’t be able to go as far, but my guess is you’ll feel it. But I’m not going to guess how much.
My husband, in high school, ran a 4:10 mile. This was considered very good for the altitude (at the time). His coach theorized that he could run it in 4 or under at a lower altitude, if that gives you any idea.
I live in Denver, and when I go to sea level–say to visit my son in Seattle–I can just run forever. It’s neat.
You will DEFINITELY feel it as other posters have said.
I don’t think (and again my only medical qualification is watching a lot of Quincy when I should have been at college) that any dangerous side affects kick in at 6kft (Wikipedia say 8000ft is when Alititude Sickness can kick in). But if you go very much higher than that you need to start thinking about acclimatising yourself to the altitude before doing anything strenuous (I flew into Cusco Peru at 3800m and would feel light headed if I stood up to fast, let alone go for a run).
Oh, god, whenever I go (from NM) to visit my parents in NJ, going running is the highlight of the trip - I can just keep running until I’m bored rather than tired.
I ran daily the summer of 2004 and also otherwise worked out - I was in pretty decent shape. That August I moved to Santa Fe, altitude ~7000 feet. After two or three days I figured I was acclimated enough and went out for a run. Granted, I did compound it by heading out on some very steep trails, which I also wasn’t used to, but I lasted less than a mile. I know a number of people with similar experiences - there’s nothing but time to get your body used to the thinner air.
It really varies from person to person and time to time.
I’m pretty good going from sea level to 5,000-7,000 feet and running within a day. I definitely breathe a bit harder but it’s not gasping for air or slowing to a crawl. I run a fair amount (30+ mi/week) and bike a lot so I’m in decent aerobic shape. After even a few days of this, going for a run back at sea level is great, I feel like Superman.
Personally I tend to notice the effect on normal exertion at around 9,000 feet - running up a flight of stairs results in me really sucking wind. At 11,000 feet or so I’m consciously slowing down even low-speed activities (hiking).
I’ve been altitude sick twice on Mount Whitney - once it hit me right at the top (14.7k) and the second time at 12k (having been to the top before and lectured my buddies about not pushing on in the face of illness, I did the mature thing and hiked back down to the trailhead and sat there drinking beer with another guy until my friends made it up and back).
My Wife is an IronMan and trains at 9- 11,000 feet. We live at 11,200. While I’m sure it does make a differernce to a lot of people, when she races at lower altitude (sea level), it never seems to make a difference. :shrug: So everyone is different.
I’ve driven sometimes and flown sometimes from pretty much sea level to new mexico and been doing strenous stuff within a day or two while being in pretty good shape and yeah you will feel it at 6k feet. At 10k feet you will really feel it.
That’s right around the threshold where partial pressure decreases oxygen uptake. VO2 max will be around 10% lower at that altitude than sea level, and similar reductions are predicted for every 1000 feet of increase in altitude. Your heart rate will temporarily increase, but your stroke volume will go down, and your blood will get a bit thicker. You gradually adapt over 4–6 weeks of living at altitude but will probably not match performance at lower altitudes.
In other words, if you’re planning on doing any significant aerobic activity, you won’t be able to do it as hard or as long as you would normally. Anaerobic performance in events like weight lifting, sprints, throws, jump distance, etc. shouldn’t be affected much if at all. Actually, throws benefit from slightly thinner air. You’ll be in no real danger from exercising since 6000 ft is pretty low as these things go. You’d have a statistically greater chance of stroke or heart attack, but frankly the odds are only infinitesimally increased over sitting at home watching TV.