Well, even a young person of 33 a HR of up to 180 when running hard is pushing your maximum rate, but should not be a problem if you are not gasping for breath. A HR over 200 should be avoided, slow down I think. The elevation is a contributor to the high HR, as you know...and a reason to slow down if your HR hits 200+.
Do you have any feeling of you heart when at rest or moving at a walking pace? Does it feel regular in its rate, or does it jump around? These facts can help analyze you situation, still with what you've said all I can recommend is what I already have, don't over exert yourself.
Thanks for the info. I did recently read that Garmin Heart Monitor could have less than accurate reading with synthetic clothing? To answer your question about when I am resting. I occasionally have a palpitation or something minor.
I was going to comment on the accuracy of the heart monitor but you've covered that.
I'm into mountains so will be under pressure for up to 9 hours and sometimes longer climbing or scrambling up rough terrins in all weathers All I can add to what Jerry has said is that your body has good days and bad days and you need to respond to what it is telling you.
Sometimes i feel real bouncy with spring in my legs and others real heavy so still go on but takle it slower with more stops to admire the view. The key is to enjoy your exercise and you will know pretty early on what sort of a day it is so tailor your day accordingly.
By the way don't become an endorphin junkie by pushing yourself too hard juat to get that 'natural' high.
From experience and knowing that i am going to put my body unfer a lot of stress I watch my resting pulse and if it rises over a few days i know that I am fighting off a low level infection of some kind so wait until it gets back to normal before going for a hard day.
Your body is not a machine so listen to what it's telling you and plan your exercise to match.