Have received this from a contact at Garmin as asked whether applying water or gel to your strap before starting an activity was a good thing to do to maximise chances of getting good results. Seems water is the answer - well if you are having problems.
We did some testing and found that residue from electrode gels does seem to build up a bit over time and reduce the conductivity of the electrode material. The same is true for liquid soap. So water is the “official” recommendation for improving the connection before you start sweating. The other advantage of using water is that you can get the whole front of the strap wet. That helps reduce what we call the “jersey flap” issue where a synthetic shirt is rubbing on the outside of the strap and creating static electricity build up making it harder to pick out the heart rate signal.
I can probably name two dozen factors that affect heart rate accuracy - some environmental, some physiological, some depend on the use case, some on the care history of the strap, etc. So I would stop short of recommending that everyone should soak the strap before use. Many people don’t even wet the electrodes and still get perfect heart rate. But if someone is not getting accurate heart rate, particularly in the first 15 minutes of a run, then that would be a good thing to try.
