'Like an addiction'

Spectacular in its violence, Krav Maga has become prominent in video games and action movies, such as The Bourne Ultimatum (2007), Taken (2008) and the X-Men series.

"From a Hollywood point of view, it looks very good," says Chris Couch, a US marine who became a black belt and Krav Maga instructor in 2014.

"They're trying to be more realistic in their fighting and Krav (Maga) is very fast, very dirty, very to the point."

Couch says he is seeing more and more fathers, but also women and children, signing up to his studio in Los Angeles.

It is not out of a desire to fight but a need for self-defence, he explains.

"We always tell people that we need to do everything that is necessary, but only what is necessary," he says.

"It's not our job to detain a bad guy or anything like that. Our primary purpose is to get away and get home safe."

Alan Garcia, a bouncer at a Los Angeles night club, has been training in the method for four years. The aim is to "neutralize" troublesome punters "before they get to the fight" but he says he also finds real pleasure in the "adrenaline rush" during training.

"It's like an addiction. I go to the gym at least twice a week," says Alex Jackson, a 38-year-old teacher.

"It may have a bad reputation, but this is something that I only do in the gym, although it's true that now I feel more confident and safe."