Karnoven Heart rate
Im not sure but I would imagine this would relate to the training intensity needed to maintain your fitness. If you are looking to improve Id push higher. But as I say Im not entirely sure.
I have recently discovered Karnoven formula to calculate the heart rate training zone and this has helped me to improve significantly.
However, there is one aspect of the formula that i dont understand:
As our fitness improve our Resting heart rate decrease , and a/c to the Karnoven folrmula (HR = RHR +%(MHR-RHR) = RHR(1-%) -%MHR) so, for the same training % zone, the heart rate declines with the RHR
.So the better our shape , the lower the heart rate we need trained at