You are right there are both types of contractions. Let me clarify lifts I would classify as concentric dominate, they would be any lift for which a tempo could not be assigned. For instance in bench or squat you could assign 3 seconds for the eccentric phase 1 second for the isometric phase and 1 second for the concentric phase. For Olympic lifts (except for jerks) and Deadlifts (I have my athletes drop the bar to save their backs) you cannot assign this tempo. This is a fairly common designation. It in no way means that they are void of eccentric contractions. Sure there is always a variety of muscle actions taking place at the same time. The core is stabilizing isometrically, antagonist are eccentrically working etc, but the action of the prime movers are predominately concentric. I'm sure if you catch deep the more the eccentric phase is more pronounced or can be emphasized, but somedays I don't want to break down the athletes so much so I assign lifting with less eccentric emphasis. But that is beside the point of this whole conversation, I'm just interested in whether or not post excercise static stretching is detrimental to adaptation, and if so is there any type of flexibility training that is beneficial immediately following strength training. I think Mike is on the right path trying not to confuse the body and hinder adaptation.