Lift before Rift

Lately I have gotten into lifting weights. Ill do a few reps right before a league game, and lately my game has improved significantly. I feel more focused, and feel as though I am making decisions faster. My scores are way over the top what they used to be. What do you guys think? Is getting my blood flowing before a game really helping me this much, or am I just getting significantly better overnight? Or is there a science behind this?