Abnormal wrist heart rate during running

Do you use a chest strap or the optical sensor? I had the same happening to me with the use of a chest strap, and applying a electrode gel didn't help either (eventually the straps do break down, I know). But yesterday I changed the battery in the HRM and that seems to have done the trick (I'll have to test further times, but a good first start).

So although the battery might not be completely empty, and you do get readings, I think it could be the culprit in this case. At least easy to try and see if it helps.

I use a optical sensor. The wrist sensor.

The optical sensor is pretty much unuseble for running. Data is much and often to high.

And running without the HR strap will result in missing a lot of data on running stats as well.

A pitty for such an expensive watch

That is NOT my experience at all...  The optical HR I see on my 945 is VERY similar to my HRM-TRI,  but the wrist data have some inertia: the chest band reacts faster to variations in heart rate. I use both systems: the HRM-TRI for biking (always) and for running series or intervals, specially the short ones (100-500 m);  but for easy runs, steady runs, "tempo" or even threshold runs (2x20 min at anaerobic threshold) my wrist heart sensor works absolutely ok.

The chest band is a bit uncomcortable for me, specially wearing it long time...   so I'm very satisfied with the optical sensor, and its HR is very similar to the chest band.  I don't see any data missing from the optical sensor!!!  (but obviously don't have the running dynamics data...  that's no essential for me in ALL my runs!  when I want see my running eficience I wear the chest band or the Running Pod) 

Try to Wear the Watch at Least 1.5 Inch above the Wrist Bones and Wear it a little Tighter.

I was so pissed this morning. I use this watch since April and before other garmin stuff. and suddenly something went wrong. 

Thank you for your replay. 

Maby it is temporary. I hope so.

Yes it isn't perfect, occasionally it will be off a bit here and there in a run... or in some cases off entirely for the run.  Just the nature of trying to detect capillary vessel expanding within skin while being swung around on a wrist!  Even with the HR strap on chest it occassionally has static issues, dry sensors, or loses connection... rare, but it happens!

This is normal for heart rate reading from a wrist. If you want reliable data go for HR strap. oHR from a wrist is good for 24/7 HR tracking not for sport usage.