Hahaha. Quite old.. 35... As someone who will turn 40 this year I guess you will call me positively geriatric! Interesting that cutting back has resulted in endurance loss but not the heart rate going back up. But it is reasonable to suppose that endurance is sort of a leading indicator with resting heart rate following it. My wife has a low resting heart rate since her 20's (never really measured it before that.) She was never a big athlete or a good exerciser. Recently she has started an HIIT program, for general fitness and weight loss. I think we will need to track the heart rate carefully now.