Basically my arms are full of lactic acid, making movement in my hands extremely sluggish and to an extent painfull. The plus side is that as my body adapts to racing arm pump as it is known will begin to reduce as my body gets better at dealing with it leading to greater dexterity in my hands.
If this is the case I think it may have a positive affect on my apm, of course that is provided i can think fast enough .