Adrenaline Addicts

A
Parachuting off bridges, cycling as fast as possible through dense forests, swimming among sharks as they are fed raw meat – three examples of the type of adventure activities that are becoming increasingly popular. But why do people want to risk their lives in such strange and often dangerous ways? Scientists think that they may have found an answer to this question: adrenaline.

B
It is commonly known that under stress the body releases adrenaline in order to prepare us for the need to take sudden action. However, scientists are now suggesting that people release adrenaline at different rates according to their genetic make-up. Adrenaline is released when potassium channels in the membrane of adrenal cells open, but researchers have discovered that these channels come in two forms, the second of which has an additional protein chain. This second channel opens more quickly, allowing the rapid secretion of adrenaline.

C
All mammals have both forms of the channel, but the balance between the two varies widely in different animals, according to its needs. 'It makes sense that a large animal like a cow has a slower, more mellow system,' says neurobiologist David McCobb. 'A small rodent, on the other hand, is easy prey and needs to be more excitable. After all, a rustle in the leaves might be a cat ready to pounce.'

D
The balance also varies among individuals of the same species. 'The level of excitement will affect how quickly the adrenal glands produce adrenaline. And that may have some effect on what people get thrills out of,' says McCobb. Perhaps, he thinks, thrill-seekers need bigger thrills to get the same adrenaline rush as more timid individuals. The risk-averse, on the other hand, do not need to push their safety limits as far before they're flushed with adrenaline.

E
Extreme sports have become increasingly popular as leisure time and disposable income have increased. New forms of sport are being developed all the time, and while each activity differs in form, they are all designed to provoke an extreme reaction on the part of the participant. But these adrenaline pursuits have also produced a paradox. While people want to experience an instant high, they still want to avoid injury or accident, and so safety considerations are normally to the fore.

F
But tragedy can strike. Last year 18 people died when they were swept away by a flash flood while 'canyoning' in the Swiss Alps. Canyoning involves sliding, jumping and abseiling down ravines and into rivers without a raft and was popularised by the French in the gorges and rivers of the Massif Central. Last month, the company which organised the excursion said it would resume trips in the stream near Interlaken, where the accident happened. A new early-warning and alarm system is being developed to reduce any risks.

G
At least two Britons are known to have died taking part in the sport. In 1996, a 43-year-old Ayrshire man died when he was sucked into a whirlpool while canyoning in the French Alps. A less dramatic, but still risky, version called 'water walking' has become popular in the swollen rivers of Scotland. The growth in extreme sports has led to insurance companies offering special policies to cover for injury and death, although critics point out that the activities covered tend to include only those which are well supervised.

H
Where once extreme sports were for only those in their 30s who had become bored in their well-paid jobs, the age profile is falling fast and the increasing popularity of extreme sports can be seen in a number of different ways. Manufacturers of sports clothing are competing to launch new ranges of clothing to cater for these young adventurers, and the Extreme Sports Channel, already popular in continental Europe, is about to be launched on satellite in Britain. Described as a cross between MTV and Eurosport, the 24-hour channel targets 14- to 29-year-olds with live coverage of extreme events. Adventure sports and – perhaps more important, the adrenaline rush which they provoke – are here to stay.

From The Scotsman