Did you just start the Creatine? I get that "pump" when I first start a new cycle of creatine. I don't know if I get a "pump" per say in my legs though...I do get dizzy and numbing / wobbly legs after most my sets though In fact, I've almost passed out a couple of times on leg days...puked several times. Back days can have its moments as well
strange, after a few sets of warmups on squat i start feelin the pump.and I can't imagine how high rep leg extensions won't get your quads pumped up