I think it works to some extent... it really pumps you up and elevates your game. worked for me. I was playing the 3rd seed, 68 in the state and i took the first set, he took the second in a close one after a rain delay. and match was already turning into a bloodshed. no one was gonna let down, in the tiebreaker, it was close until 6 all, and I hit a great shot 7-6 and I let out a loud "cmon" (not my first), and i was really pumped then, winning 2 straight pts, and on his serve down 6-9, i crushed his second serve to the corner, and finished the match with an overhead. 10-6. My adreneline was really going in that tiebreak, he had no answer for my bruising shots... if i was that focused and pumped the whole match, i woulda been over in an hour.