I have a 3-4 day a week weight workout plan, each day focuses on squats, bench press or deadlifts as the primary and some auxiliary exercises (overhead press, crunches, etc.). I've recently added very light exercises at the end of the main workout to help stretch out muscles, etc. with the hope of doing an active cool down and prep'ing for the next workout. For example, if today is bench press day and tomorrow deadlift, I might do some very light deadlifts or good mornings. I think this is helping in that the next workout I'm able to lift a bit heavier. The question: Is this post workout, light workout actually helping because it's stretching the next target muscle group OR is it mostly a psychological thing where my mind is focusing on the next workout sooner?
I would say a little bit of both. When you do those "Warm-ups", you're still working out those muscles. You go home and sleep, where you recover (build strength). Then, you go back to the gym go heavier. I say both because it's one of those things, if you believe it works it will.