Heart Rate measurements wrong during activity

I have the exact same issue now for over two months. I keep my watch clean, updated and snug on my wrist, nothing has changed, but the HR is way way off. Under intense cardio I should be about 120-130, but the past few months it's been 79-89, definitely off for me. Not sure what else to do, I have done all the updates but still just doesn't work right.

All of a sudden I can not get out of warmup zones when before I was 128 BPM CARDIO on treadmill at 2.0 because I'm 150 lbs overweight. Last 3 days I have pushed myself at more than 2.5 and still it will not raise much over 103.  

I have this happen sometimes and hate it. I will say that taking the watch off 10 or so seconds and then putting it back on seems to reliably fix it. It's annoying as hell - and it's clearly an algorithmic thing (I doubt it has anything to do with cleanliness or exactly how tight or exactly where on your arm it is). It's likely that some parameters go far enough out of bounds (extreme uptick in rate etc) and it gets clamped down and never gets back "outside" of the box - but taking it off seems to let it reset it's moving average.

I've had the same problem which worried me considerably in case it was a sign of some sort of heart problem. Today when it happened again, I checked the sensor list and one sensor was connected to the watch despite it sitting in a drawer. It was this that was transmitting zero. I disconnected all the sensors from the straps and the problem was solved.

• I agree. My Garmin watch gives me completely inaccurate heart rate readings.  My b)watch says I am at 94, the exercise machine I am on 131?  And my body feels like 131.  The Garmin is way off