when does altitude start to have an affect?

Altitude is exponential. About 3000 feet is where you might start noticing the effects, and gaining (small) increases in red blood cells. For every 1000 feet above that, the effects increase exponentially. The difference between 5000 feet and 0 feet, is the same as the different between 5000 feet and 7500.

Think of it like swimming to to bottom of a deep pool, but in reverse. The higher you go, the lower the air pressure, and as you conine to go higher, there is less and less air above you pushing down on the air you are brrathing, making it harder and harder for your lungs to fill.

Your lungs full by (basically) creating a low pressure zone inside you that the air rushes into to equalize. The lower the air pressure where you are at, the less is needed to equalize the low pressure zone in your lungs. Hence less oxygen delivery.

Alty wrote:

Altitude is exponential. About 3000 feet is where you might start noticing the effects, and gaining (small) increases in red blood cells. For every 1000 feet above that, the effects increase exponentially. The difference between 5000 feet and 0 feet, is the same as the different between 5000 feet and 7500.

Think of it like swimming to to bottom of a deep pool, but in reverse. The higher you go, the lower the air pressure, and as you conine to go higher, there is less and less air above you pushing down on the air you are brrathing, making it harder and harder for your lungs to fill.

Your lungs full by (basically) creating a low pressure zone inside you that the air rushes into to equalize. The lower the air pressure where you are at, the less is needed to equalize the low pressure zone in your lungs. Hence less oxygen delivery.

+1

You should just barely began to notice altitude at 1000m. You can start using it as an excuse for slower times at 1500m. It will start significantly slowing your times at 2000m. Even the Colorado natives feel it at 3000m.

This only matters for distance running. Sprints will actually be faster at higher altitude. (Don't be a moran like me and bet someone you can break 4:20 at sea level because you can run some fast 400's in Salt Lake City.)

Jruns wrote:

affect? effect? whatever.

normally i live in an area with about 800-900 feet of elevation

But I'm travelling for the summer and I'm staying in an area that has about 1,030 to 1,100

Does it even have an affect?

You will feel ZERO difference as long as the weather is the same. I live at sea level but the best place to run is a 30min drive and it is about 200-300ft above sea level. It feels exactly the same because the difference in oxygen and air pressure (or whatever) is minuscule.

I was living and running In Lusaka Zambia which was between 4000-4500 feet. Whenever I would go back to NJ or DC and do a race, I would do better than expected. I always chalked it up to a combination of the elevation difference and the perfectly paved roads and racing conditons of suburban America compared to hilly, pot holed Africa with drivers not trying to avoid you.i did go t Addis for work once which is between 7500-8500 feet and a 20 minute jog made me dizzy!