I've got a nice new birthday present of a Timex HRM (T5D741)and after figuring out how it works I see that the zones 1-5 are calculated using my entered max HR (i.e 90% of 177), not my working HR - i.e. 90% of 136 + 42 (resting HR).
This means that for e.g. the 60%-70% (106 - 124)zone programmed in the HRM is quite different to the 60%-70% (124 - 137)zone based on my working HR, which is what I had expected on the HRM.
How should the zones be calculated ? MHR or WHR ?
Has anyone else come across this and what do you do ? There is a manual zone which can be set each time, but that seems a bit of a nuisance.