QUOTE(Coach Eric @ Jul 9 2007, 05:39 PM)

Actually being at elevation raises your resting heart rate and decreases your maximum heartrate, so all the usual heartrate guidelines go out the window. Your rate of respiration is a good guidepost of your exertion level so be conscious of your breathing.
Sorry, but I have to disagree with Coach Eric. Your heart rate monitor is going to be your best coach when running in altitude. Your heart rate automatically adjusts for the additional stress that altitude places on your body. Your aerobic threshold is the same no matter what altitude you are running at.
What does not apply at altitude is your pace! If you are use to running at a 10 minute/mile pace in Portland, then your pace will be significantly slower at 7500 feet elevation. After a few nights of sleeping at the altitude, your body will start to adjust and you will find your pace starting to return to your lower altitude pace. This is assuming that you are getting a good night's sleep each night. Try to let your body wake you up by itself. If you let it, your body will naturally wake you up when it is done repairing most of the previous days damage.
If you are tracking your resting heart rate (RHR) each morning, you will be able to use it to determine how quickly your body adjusted to the altitude change. (As always, good nutrition and being properly hydrated will help decrease the time to adjust, also.) Assuming that you don't get sick or have some other increase in your body stress, your RHR will start decreasing to your lower elevation RHR level on a daily basis.
You may have to walk the first couple of days, but if you rest properly and your body adjusts correctly, you should see daily improvements within 1 to 10 days.
Eric