Just a Tech question (and who doesn't love tech questions?)

Does anyone know of a heart rate monitor that specifically does this: Say your target HR is a given band, perhaps 115-125.

I just want a display that shows **total elapsed time, inside, that band**.  Thus, the stopwatch only advances, if, you are in the target band.

(Example - you jog 5 mins at 120, 3 mins at 130, 1 mins at 120, 5 mins at 100 ... it would now show "6:00". During 100, it would simply sit at "6:00" and not advance.)

I realise any advanced watch includes a file of your HR over time; of course you could calculate time in any band afterwards.  What I'm saying here is, I'm looking for a simple live display of elapsed time-in-a-band.

Can anyone remember seeing this particular function on a watch?  Thanks!

I lean towards garmin FWIW. The function I describe is not on my beloved garmin 401, nor my polar (it's that cheapest polar).

Come to think of it I guess it would also be great if it showed your total time in band(s) cumulatively over weeks - I'm sure this must exist too?  But I'm really just looking for a simple live display, this run, of time-in-a-given-band.  Ideally with BIG numbers!  Man, I hate small numbers on watch displays.  (Another reason to love the 401!)

Anyone remember seeing this - thanks!!!!

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*An advanced bonus question for programmers amongst us: someone must have come out with a sports watch that one can program?  Load little javascripts or the like, and get exactly what you want on the display? Is there such a thing? Cheers*