Originally Posted by
Latitude65
from a functional point of view does it matter whether what the limitation is?
Further, it is not necessary, or even useful to know the maximum heart rate cause as long as tissues are perfused and there are no other symptoms. That is why the Breathing Test is such a useful tool.
The only practical reason to know your MHR is if you want to use it to set training zones, which was the op's original inquiry. I agree, from a heart health point of view, it doesn't tell us anything.