Heavy metal fans might want to consider updating their trademark move - headbanging could really put their health at risk.
Doctors who treated a Motorhead fan with a blood clot on the brain have said the condition was caused by his habit of headbanging.
The 50-year-old German developed the condition after getting carried away at one of the hardcore rock band's concerts.
It is the fourth documented case of subdural haematoma linked to headbanging - one of which proved fatal.
Specialists treated the fan at Hannover Medical School two weeks after he started suffering a constant, worsening headache that affected the whole head.
A CT (computerised tomography) scan confirmed that the man had a subdural haematoma - a clot caused by blood leaking into the space between the skull and the brain - on his right side.
Surgeons successfully removed the clot via a hole drilled into the skull, leading to a full recovery.
Subdural haematomas are most often caused by blows to the head, but the patient could not recall suffering such an injury.
However, a month before attending hospital he had been to a Motorhead concert where he joined other fans headbanging to the fast and furious music.
Doctors writing in The Lancet medical journal said: "Our patient had no history of head trauma so we assume that headbanging, with its brisk forward and backward acceleration and deceleration forces, led to rupturing of bridging veins causing haemorrhage into the subdural space."
A review of the medical literature revealed three previous cases where headbanging led to blood clots. One, an acute haematoma, resulted in sudden death.
Other conditions attributed to headbanging have included a torn carotid artery, whiplash injury, fractured neck, and air in the chest cavity.
The doctors defined headbanging as "a contemporary dance form consisting of abrupt flexion-extension movements of the head to the rhythm of rock music, most commonly seen in the heavy metal genre".
Motorhead were one of the pioneers of "speed metal", marked by fast tempos of more than 200 beats per minute.
The surgeons, led by Dr Ariyan Pirayesh Islamian, ended their report by paying the band a veiled compliment.
"This case serves as evidence in support of Motorhead's reputation as one of the most hardcore rock'n'roll acts on earth, if nothing else because of their contagious speed drive and the hazardous potential for headbanging fans to suffer brain injury," they wrote.