Altitude

If I--as a runner who has never run at altitude before--was told that it would take the better part of two weeks to recover from running 10 miles (6 of which were at 10K race pace) at 5,000-plus feet, I would have responded, "no way." I also would have been wrong. It's not the lack of oxygen in the air, but the lower barometric pressure, that causes the beneficial effects--or, in my case, a large buildup of lactic acid--of running at altitude. I've learned that no matter the elevation, the air we breathe always contains 20% oxygen. It's the barometric pressure that varies. The higher up you go, the less pressure there is. The less pressure there is, the less oxygen there is in your blood...

I didn't seem to notice much of a difference in my performance at 5,000-plus feet. It wasn't until I ran again at sea-level when I began to notice a difference in my performance. My legs would literally not go. I had a very difficult time last week and even this week through Thursday. I'm not sure how coming up short on my 18-mile long run will affect my marathon performance, but judging by this week's long run of 15 and change, I would say that it will not affect it at all.