drtgirl:

Here's a link to a post that may give you some more thoughts:
http://forums.teamestrogen.com/showthread.php?t=18381

I'm starting to use my HR measurements as a guide to pacing myself...for instance, if I'm coming up to a steep hill, I know that my HR needs to be in the 140 to 160 range, or I'm not going to have the juice to climb.

Yesterday, on the Hilly Hundred's steepest hill, I crested the hill with a HR at about 190...but my HR was 140 at the bottom. If I had been at 160 at the bottom, I probably couldn't have made it...