Associate Professor Andrew McIntosh, co-author and professor of biomechanics at UNSW, said "If you observe people after concerts they clearly look dazed, confused and incoherent, so something must be going on and we wanted to look into it."
Maybe they should have looked into the 'recreational chemicals' ingested by concertgoers as well. I have certainly come out of metal shows looking 'dazed, confused and incoherent' and it's got nothing to do with headbanging, baby!
Well actually, those days are long over for me. I quit smoking 'tea' before concerts way back in high school when I went to a Dio concert and couldn't remember a thing about it the next day! I thought, man what a waste of money, and saved my indulgences for other opportune events like high school football games and marching band.
The full headbanging research story is here and is pretty funny. I suggest reading the whole article. Bang your heeeeeeead!