I don't find wingfoiling all that physically difficult. My heart rate watch doesn't agree.
I relish the physical sensation of strength holding the wing for long reaches and the feeling of acquiring skills and improving. I never felt all that wrecked at the end of a session.
According to my watch, when kite foiling I generally cruise around 2 for training effect, 110-120 bpm with a max of 130-140 bpm. When wingfoiling my training effect is about 5 and heart rate averages around 130 with peaks at 160-180 bpm. My watch thinks I should take it a bit easier. It's a good thing I stop recording my session before I walk 200m back to the car up a steep path carrying about 17kg of gear.