Garmin Heart Rate Strap problems

The Garmin Heart Rate Strap I use for my training sessions is problematic, the main issue being that it often shows (and records) elevated heart rate readings. I'll be running along at an extremely easy pace and look down at my watch and see 170bpm when I know it is actually around 135bpm.

This elevated reading usually occurs in the first ten minutes or so. Then it will settle down and behave itself for the rest of the session (but not always). Any headwind that causes my top to flutter against the strap nearly always triggers the problem as well. I assume the fluttering causes static interference or similar. Last season I did most of my sessions in a tight fitting tri-top, but this is not as convenient during the cold months of Winter.

To my knowledge Garmin has release 3 different straps, 1 hard and 2 soft versions - I had tried them all. Brand new, the straps usually work well, but it doesn't take long for the same problems to arise with each one. Keeping them clean, especially the contacts between the actual transmitter unit and the strap helps, but does not eliminate the problem. Some running and cycling tops seem more problematic than others, maybe different materials are more prone to static electricity (assuming that is the cause).

Obviously the unreliability of the heart rate readings is extremely frustrating when you are trying to train at a particular heart rate. Since Ironman I have turned off the heart rate alert functionality, because I got sick of it continually beeping despite me running at a very slow pace. The result is that a lot of my runs have crept up a little too high in pace (and actual heart rate), so they have not been quite as effective as they should. It is also annoying when you use training software to accurately report how long you have spent in each heart rate zone for the week or month - ideally you want to do at least %80 of your training in zone 2 (aerobic).

Through trial and error I have identified the running tops that seem to be the worst offenders for interference. I have also discovered that making sure the chest contact points are very wet before the session starts greatly reduces the initial elevated readings. With these new measures in place, I have re-activated the heart rate alert setting on my watch. Hopefully I can keep the strap problems to a minimum and continue to improve my aerobic training base.