There's reason to believe that yes, doing lower body training before upper body stuff potentiates upper body strength/size increase above that from just an upper body only session. On the other hand, I could argue that the higher volume the session (all other things being equal) the more stimulus for growth and strength has been given and thus, it's really about total body volume/loading/intensity and not the training of the legs before upper body, per se'.For the intermediate trainee, does training the bench/press after the squat/deadlift produce a hormonal response that is more beneficial to getting big and strong than the slightly heavier weights (maybe 5%?) that training them first on separate days would permit?