I turn 75 next month. For six years, I've been on a low dose of a beta blocker for PVC's. When I awaken in the morning, my resting heart rate is low 50's. It drops into the high 40's while sleeping. During our daily five mile walk which includes some short hills at an average elevation of 4200', my HR maxes out around 135-140. Two years ago, I climbed Piestewa Peak in Phoenix and maxed my HR at 161. Two months later, I did the first two miles of the Kalalau Trail in Kauai and maxed out my heart rate at 156. When the weather cools, I will do Piestewa Peak again. When I was in my 40's-50's that climb would have my HR maxing out at 190 as measured by a chest monitor.