Fewer still would have been prepared to throw themselves off a bridge or crane, with just a stout piece of elastic to stop them hitting the floor.

Tabloid newspapers ran articles on the effects of the sport on heart rate and blood rushing to the head.

But now bungee jumping is regarded as a fairly pedestrian activity, and would possibly draw no greater crowd to a summer fete than a good bouncy castle.

Ice climbing presents many risks, and participants must be experienced mountaineers

Adrenalin junkies now have their pick from a variety of extreme sports, and new activities are emerging all the time.

Tragically, that choice can lead to accidents like Tuesday's, where at least 18 people lost their lives whilst canyoning in the Alps.

But incidents such as these are unlikely to put off many newcomers. The increasing numbers of extreme sports titles hitting newsagents' shelves are an indication of the growing ranks of adventure-seekers clamouring to have a go.

"I am sure it has to do with the longer hours that people are being made to work," says Sarah Snowball, of Zest, a London-based company offering adventure breaks and activities such as riding on the wings of Tiger Moths, skiing and Arabian stallion riding.

"People's leisure time has become far more precious to them and they want a complete break from their working environment.

"If they do something, even at novice level, like mountain biking, they are able to get out of the city and completely work off the stresses of the office."

James Swankie, of outdoor leisure company Snow and Rock, says that many people often experience extreme sport for the first time on holiday - and may then seek out specialised holidays in the future.

He said: "Definitely a big attraction of what people call extreme sport is the ability to combine it with travel.

"People might chose to go white water rafting in the Himalayas or the Andes - or surfing and windsurfing in Hawaii, where there are 80ft waves. It's being able to have a complete adventure.

"Extreme sports are getting more media coverage - the X Games were covered on cable TV, and people watching want to give different sports a go. "Another important aspect for some people is that you don't have to join a team - these are activities which most people can do and organise themselves or with their friends."

Zest's Ms Snowball: "People want to completely shake off the office"

But what counts as extreme? Mere skiing, rock climbing or canoeing seems fairly tame compared with base jumping or free diving.

Mr Swankie said: "There's divided opinion on that - a lot of people judge that a sport is extreme if a risk of death is involved.

"Many established sports have an extreme end to them, with professionals and enthusiasts pushing the thing as far as they can take it and themselves.

"They have to keep pushing it to get a buzz from it."

Advances in canoe-building technology, for example, mean that extreme paddlers can now take their craft over giddily high waterfalls and rapids, where there are sometimes more rocks than water.

But one-time member of Oxford University's famous, if not notorious, Dangerous Sports Club, and its successor, The Stunt Factory, Dr Martin Lyster, says there is more to it than fashion and technology.

Author of The Strange Adventures of the Dangerous Sports Club, he told BBC News Online: "The sports and activities are themselves enjoyable and thrilling things to participate in.

"They test self-reliance and confidence, and one's ability to go past our own limits, and the limits that other people put on us.

"Beyond that, it's an animal thing. We all have within us primitive instincts that seek release. We are conditioned and used to living in what is a safe environment, but as human beings we are programmed to deal with environments other than that."

Windsurfing can be taken to extremes

He said that this was apparent in the way that people drive aggressively and behave competitively.

As well as being an expert hang glider and parachuter, Dr Lyster is also a keen base jumper and street luger.

He said: "Street luge has really taken off - in Oxford there are regular events when areas are closed to traffic - and we sent a team out to the Street Luge championships in Austria at the end of June."

Street luge involves lying on what looks like an extended skate board, belly up, and hurtling down hills and mountainsides.

"Base jumping is far more specialised," says Dr Lyster, "It is jumping from a fixed object rather than an aeroplane, but you have to have experience of parachuting to do it.

"It is pretty much frowned upon, and there is no governing body for the sport in this country.

"It is not against the law as such, but you generally have to commit some kind of trespass offence to get to the commencing point.

"It is not something that you could just have a go at. I have always got away with my jumps, but it can be very dangerous indeed."