Training after 65

I have been competing in Masters since I turned 25 in 1974, self coached the whole time. From age 35 to 62 I was slowing down very slowly. I started slowing down more rapidly at 63, but it wasn't until age 69 that aging(and injuries)were noticeably affecting my training. I need more rest and more recovery time now. There is precious little information on training at a high level after age 70.What experience, either personally or as a coach, do you forumites have with this age group? One accomadation I am making now is to take my pulse regularly during workouts and pausing a set to let it get down to 130 before proceeding. This seems to help. Noteably, depending on the equation, my maximum heart rate should be 150-160, but I can easily get to 180 with sprints (I enjoy sprints and swimming fast, that is what I find fun.Long slow swims are intolerably boring for me.) Again, what has worked for others over age 70?