@Andrew – that sounds like the right way to do it to me. If I recall, we only get Pa:HR if there’s GPS data as you noted.
@Saadia – I have the same issue with my HR monitor and watch. Very frustrating sometimes as it’s unpredictable. Doesn’t happen often enough to warrant new gear, but just enough to frustrate me once a month or so. Was hoping it wouldn’t happen during the test.
Question for the group – assuming my % drift is good, is the top of my Zone 2 going to be:
(a) the number I was aiming for during the test? or
(b) the average HR of the first half of the test?