I'm sure DMC has said in his coaching blog that running doesn't have much impact on recovery in climibng specific muscles. So I think he would say if you are after active recovery then it shoudl be super easy climbing, focusing on movement skills etc.I don't know much though, I just parrot what I most recently heard like a mynar bird.
I know nothing, but I'll say this: running, however easy, is a load more work than easy climbing. easy climbing is really pretty low effort stuff in comparison to even a gentle run - just look at the size of the muscle groups involved.
Have you come across this paper? :Effects of Active Recovery on Lactate Concentration, Heart Rate and RPE in climbingUnfortunately it relates to using active recovery during a workout rather than between workouts but might provide some clues. I was drawn to the comment that "The use of larger and or alternative muscle groups in the active recovery may benefit lactate clearance"Don't know if it counts as active recovery but spraying cold water on your forearms after a session has been used to aid recovery.
@ Duma - I actually disagree about the easy running being harder than easy climbing and oddly enough for the exact reason you mentioned. You have really big muscle groups to propel you running, which makes it easier.
I think that how 'hard' climbing is, is often underestimated for a number of reasons. Climbing may involve quite a large, or a small percentage of your body muscle mass; it is not just a series of isometric finger flexor contractions - stemming up a groove, you'd be using abdominals , everything in your legs, as well as yarding on any available holds.