HRM position

The HRM detects very small electro-chemical impulses that create a very small change in the electromagnetic field. Since the changes are so small, proximity to the heart plays a role in the effectiveness of the HRM. This is also why areas with significant EM interference can cause bad readings.

Shane

Static buildup from tech fabric shirts (polyester) can also cause a HR monitor to misread.  It's especially noticable to me when it's cold and dry out.

Try wearing something snug - like a tri top so it's not constantly brushing against the HRM.  You can also try a different fabric.  Cotton is fairly neutral.

Edited by spudone 2014-11-05 5:09 PM

I always run in my tri top and shorts, so I think it is a position that made such a huge difference..

Edited by woosh 2014-11-05 5:16 PM

Eh, who knows? There is nothing in your belly that will give off a regular pseudo-heart beat.
If your belly is smaller than your chest, then it will be able to slide around more once it gets there...thus static derived HRM spikes.

The strap should be on pretty dang tight. I have mine centered and right above my xiphoid process. When I take it off, there is a very clear red mark that persists through a shower. However, it is not uncomfortable and unless I am cycling with a loose jersey, I rarely get spikes and never ever does it fall down.

The strap needs to be replace about once a season. I've replaced batteries and still get strange readings. The sensor is usually good but the strap can go bad.

Fortunately Garmin sells the strap replacements.

Next time, grab a polar replacement strap. The garmin pod snaps right in and they are quite a bit better quality...last longer and fewer spikes!