This is probably a question for AJ but if anyone has input I would welcome it. Last week I did the bike LT test workout set out in the training plan. I did the workout correctly, but I am fairly sure the HR monitor on my watch malfunctioned or somehow was not recording my heart rate properly. The first 10 minutes of the 20 minute test were fine — my avg beats per minute was in the general (high) range where I would expect it be given the high intensity of the workout. Then, for the second ten minutes, the heart rate (as recorded on the watch) dropped significantly — a clear linear downward slope if you were looking at BPM vs. time on a bar graph — and then stayed there for the remaining 10 minutes, even though my intensity remained the same (same avg pace, RPM, etc.).
My question is: is this normal? Is this something that has happened to others, or something common with these watches? And finally, what should I do? Retake the test? If so, when? Return my watch? Cry in a corner?