I've done some mountaineering, so I thought I would add my 2 cents.<br><br>
The altitude might impact your performance, but 8,000ft is generally not high enough to suffer from actual <i>Acute Mountain Sickness</i> (AMS) aka Altitude Sickness. Here in CO, a few skiers each year suffer from AMS, but those are typically the folks who flew in from sea level and hopped right on a chairlift to 10,000 ft.<br><br>
So if you decide to go sight seeing and ride the Gondola, take it right back down if you start to feel queasy. Better yet, if you want to go up the mountain walk up. Don't go to high to fast.<br><br>
Emphasizing a point that everyone here has made: drink lots of water- more than you normally would. You loose more water than typical just by breathing at high altitude, and dehydration exacerbates altitude problems.<br><br>
Like Coach said, genetics is a determining factor in acclimatization. You might not notice it at all. If you are flying straight into Steamboat you might feel a little out of breath at first, but that will pass. You can expect to have a higher resting heart rate and breathing rate the first night, that will slow down after a few days. As Coach said, to truly acclimate it takes weeks, not days- however several extra days before the race will help a lot.<br><br>
The initial symptoms of AMS are headaches and nausea. If you experience mild headaches and nausea when you first arrive, drink a lot and rest. If the symptoms get worse rather than better (puking, pounding headache), go to the hospital. The only real cure for AMS is to go down to a lower elevation. If you are running your race and you feel light headed or nauseous, just slow down and take it easy.<br><br>
Like I said to begin with, it is unlikely that you will have any problems at 8,000 feet.<br><br>
Have fun- Steamboat is beautiful in June, and there will still be snow on the peaks this year- it has been a great winter!