[Scott Johnston]

Krizz:

The only explanation I can think of for a 15bpm drop in HR is some sort of glitch with the monitor.  Did your perceived exertion stay the same during those 3 minute periods as it did on the rest of the test.  It seems that even if you exclude those 3 minute drops in HR you would still get no or only a tiny amount of upward HR drift and perhaps the HR average would 160.

If you have been diligently training in Z2 for 3 months since that last outside test it is not at all unlikely that your AeT HR has moved more than 3bpm.  If I were you I would start using 165 as the top of Z2 for the next few weeks and then test again.

I hope this helps,

Scott