It's called "Praveelo", and it's used to remedy back ailments.
Though I think it can be used for something else 😀
This thing has "Tie & Tickle" written all over it!
Ancient Russians pretty sure borrowed this strange contraption from some ancient crazy villain, maybe that legendary Baba Yaga who remains alive up to now only in their folklore; it was in that time that they united, searched, found and finally plundered her demonic damned hut; and there among other impious artifacts they have found these other-worldly devices
But tbh, it seems to be too much elaborated for ancient townsmen, maybe they disposed smth similar but much simpler, like an enhanced type of a horizontal bar.
Oh my...just imagine the possibilities with that setup!