I always run too fast and end up getting injured because of it. So to solve this problem I bought a garmin 305. Today I planned on doing a 4 mile easy run at around 9min/mile pace. Although I found it quite difficult to run this slow, I seemed to be getting the hang of it by the end of the run. However, although I felt really comfortable throughout the run my heart rate was really high, generally above 180 bpm. My MHR, calculated from age, should be around 185, so I really don't know what's going on. I realise that this method of calculating MHR is not the best, but it can't be totally out, can it? Any suggestions as to what's going on?