With the use of Intervals.ICU I’ve noticed that my heart rate at a given power target is generally lower during the later parts of a 2-hour workout. Intervals.ICU calls this decoupling. Below are a few of my workouts recently with my heart rate and power output compared. This negative decoupling seems illogical to me, as I’ve always been taught that the heart rate should increase relative to the power output. Does anyone have any ideas as to why this might be?
The pink number is the 1st half
The orangeish number is the 2nd half