Originally Posted by
bobthib
My Cardiologist and my Personal Trainer both said to keep my HR at 85% or less, and there is other references that advise against exercising above 85%.
Presumably, if you have a cardiologist you have some CV issues. Normally, with a healthy heart there isn't any reason to limit your HR.
As others have suggested I would try and verify what your current MaxHR is for running. Perhaps this is not possible if you aren't supposed to stress your heart. Ideally you would find a hill and run up until your HR was at it's threshold level (i.e. the rate you would run a 10k at) and then sprint as hard as you can for 30 Secs. This should provide your MaxHR. Maybe you've already done this as part of a stress test?
If you're bumping into the 85% threshold so easily it sounds like your MaxHR is higher than you think.