I'm not the record breaker type, but I can clearly see there's room for improvement in this one.
So far people have used their legs with knees straightened, and an arm holding half an arm, presumably the speed taken from the part of the arm furthest from the player.
the room for improvement here is taking a whole arm (pec-hand), using both in the other hand, using both pecs, elbows and wrists and holding the arm from the hand side, while using the legs as coveniently as possible utilizing also the fast knee.
Sorry if this was sherlocking...