i'm 63, reasonably fit, do plenty of exercise and i've had resting heart rate about 64 to 67nfor long time, and my cardio fitness zone thing has always been very good. The score if usually 42to 43, which it states for my age is excellent. Nothing has changed exercise wise in past couple of months, yet this cardio zone , which i hadnt looked at for a while has gone down to 33 ! which it states as GOOD for my age, but its dropped 10 points for absolutely no reason as i've more or less done same amount of exercise in that time. So why has it stopped functioning correctly? It cant have dropped like that when i'm doing the same thing and no weight gain etc...?
Moderator edit: clarified subject.
