At 56, you shouldn't have to take more than 2-3 days to recover from even a kick-yer-a$$ hard ride; and if you go a whole week you're not just resting, you're losing conditioning. I do agree with KoffeeBrown, you should get a book or two on HRM training - and a HRM to go with them. I think you'll find you're training in the 'dead zone', which IIRC is about 65-80% of MHR. (Sorry, I lost my HRM book. ) That seems to be the 'comfort limit' for most people; but you don't improve at that exertion level, you just get tired. I try to include ONE ride per week where I push my HR to about 95% for an hour or so, followed the next day by a 60% ride, which is actually harder to do than the hard ride. After a month of doing that, the results are apparent!