Yellow is watts - hovering at 200 the entire workout.
Red is HR - gradually increasing, then spiking halfway through.
The reason? Green. That's cadence. Kept the gearing low so I could run endurance power at a high cadence, then downshifted 2-3x for a cadence "jump" halfway through to elevate the HR further. Not sure if there's any training benefit, but it was more fun than holding 200 watts at a more natural cadence.