TennesseeJed wrote:
Is it common for the actual watch to be the issue? I considered the HRM/Strap. I have noticed the occasional faulty spike more frequently lately, usually at the beginning of a run lasting 30 seconds or so. I usually just lick my hand, and wet down my pads and skin and it goes away shortly. I assume the contact points are not wet enough or there is some static in my shirt. That said, I have ruled the strap out because I use the same strap on the bike where I am not seeing the same lower hr values.In my experience chest strap data is more reliable on the bike. In cold weather or some other circumstances, my chest strap used to give odd readings on the run, but the bike is always robust. I presume this is entirely down to movement. The strap is less likely to lose contact or have interference from clothes when your upper body isn't moving about much on the bike.
However, it seems highly unlikely to me that you'd have consistent errors that show a pattern like the one you describe.
Training at low HR can/will reduce the HR at which you run a given cruising pace. Increased fitness may reduce how high you can comfortably drive your HR since muscle strength and demand may not have kept pace with CV improvements. However this would impact the bike too and while the values might be different, I'd assume you'd still see similar responsiveness. The fact that your cycling HR still responds much as before does make it much more confusing.