Just noticed a trend over time that I thought I could pitch to the forum to ask about. I noticed that when go for a z2 ride, my heart rate tends to trend downward over time the longer I go. When I start my effort, my HR rises normally but as the time ticks up to 1-2 hours, I notice my HR drift is actually downward rather than going up as expected.
Is this simply due to me cycling at a very manageable pace? Should I expect an increase in HR over time even at Z2? Thoughts?