heartdisease shivers

I had open heart surgery about 10 years ago.
Lately when I exercise like hiking my body overcomes by shivers when my heart rate goes up.
I also noticed this shivers once in a while when I am not exercising.
I am 53 and the reason for my surgery was that my body over the years didn't generate any good cholesterol.
Don't smoke never was over weight just bad luck I guess. I am in good shape and I am worried about this shiver thing...

Gunther, welcome to the forum Eventhough this might sound corny, I strongly advise you to see your physician. Only he, and he alone, can test you and see what the problem might be here. I would love to assure you over the forum but that would be terribly irresponsible.

So, please go see your doctor to rule out any conditions related to your health.