I dont now but im on my 3rd week of my athletic training and such and my energy has never been better. I lift with a friend for around 2 hours i do 30-45min of cardio and im never tired till im ready for bed. Im not complaining though i like it lol. Next week is back to 5x5 for 3 weeks should be fun :P probablymore fun then high reps anyways i hate it.