Aging athlete - law of aggregated miles?

STrooper

Age 61, with a fitness level of 28. (Well, I do say I'm not 27 any longer). That is due to my high measured maximum heart rate, my low resting heart rate, and the ratio of height to waist size. Now a few years ago...not so much. When I plug the data in from seven years ago (when I was 54 and at my heaviest and least active), it estimates my fitness age at 75.