Taking it to the limit in the Everest of exercise

WHEN Melbourne's inaugural Ironman - one of only 30 in the world - is held next month, weekend warrior Robert Peyerl will have one goal: to finish.

Consisting of a 3.8-kilometre swim, 180-kilometre bike ride and 42.2-kilometre marathon, the Ironman is the longest and toughest of the popular-length triathlons. So tough that only the elite worry about time goals. For everyone else, the main concern is to make it to the end.

''That's my aim (to finish), my Everest,'' says Mr Peyerl, 44, of Southbank. ''It's been a fantastic journey.''

Melbourne's Ironman field - capped at 1700 - sold out in just over five minutes, with the 35-45 male age group the largest category. This was the ''fastest-selling event in the history of Ironman'' competitions, according to Ironman Melbourne spokeswoman Lisa Pringle. The first Australian Ironman, held in 1985 on the New South Wales north coast, attracted just 40 entrants.

The rush to buy a $775-spot on the Melbourne starting line illustrates the soaring popularity of not only Ironman and triathlons but all endurance sports, including marathons and alpine biking.

According to Triathlon Australia chief executive Anne Gripper there are 120,000 entries in a typical triathlon season from an estimated 80,000 triathletes nation-wide.

''People of all ages and abilities now think it's possible to do a triathlon,'' she says. ''In previous years it was seen as something a bit specialised - you had to be a super-elite athlete to even think about it.''

She believes the popularity stems from the sport being relatively new - triathlons started in the United States in the early 1970s; Hawaii hosted the first official Ironman in 1978. ''Triathlon is new, it's got a contemporary feel, races have a real race-day buzz - people get excited about them,'' Ms Gripper says. But it is the Ironman competition that is the pinnacle of the sport, according to Ms Pringle. ''It's an enormous challenge. I don't think you can explain to people the enormous pride, relief and feeling when you cross the finish line. It's not just a physical thing, it's a mental thing. Your mind is screaming at you to stop but you push through those barriers,'' she says.

The athletes preparing for the Melbourne event know the threshold Ms Pringle is talking about. The term ''weekend warriors'' doesn't do them justice. They train seven days a week and often more than once a day. Next Wednesday, for example, Mr Peyerl will swim four kilometres in the morning, do a 10-kilometre run at lunchtime and a 90-minute bike ride at night. All while juggling a job as general manager of a training and recruitment business.

''It's the technical and mental challenge - overcoming adversity,'' he says. ''It's a journey. It's about the training that you do and the people that you meet and trying to find the time to balance things (in your life).'' It's the first Ironman for Mr Peyerl, who has been doing triathlons for 14 years, including several ''long course'' events (half Ironman).

Australia hosts two other Ironman events, at Port Macquarie and at the Western Australia town of Busselton. There's also the Challenge Cairns - a full distance triathlon not associated with the Ironman brand.

The boom in endurance sports is also evidenced by the growing popularity of the Melbourne Marathon. For example, in 2010, there were a record 5026 finishers; in 2001, just 1290 runners completed the course. And new types of endurance sport are appearing, most notably Tough Mudder, a 20-kilometre obstacle course held in gruelling and muddy conditions. Tough Mudder is held around the world with the first Australian event to be held next month on Phillip Island. Up to 10,000 are expected to take part.

However, despite a subset of the population getting very fit, Australians overall are exercising less and getting fatter. Australian Bureau of Statistics figures show the proportion of adults who exercised regularly fell from 31 per cent to 28 per cent between 2001 and 2008, while the proportion with a healthy body mass index fell over the same period from 47 per cent to 42 per cent.

But ultra-endurance sports may bring health risks of their own. An Australian-led study, published in the European Heart Journal in December, found that five of the 40 ultra-endurance athletes in the study had scarring of the heart muscle, or fibrosis. The five afflicted athletes had competed in endurance sports for longer periods than the other 35.

David Prior, a heart specialist at St Vincent's who co-authored the study, said that although the athletes with fibrosis did not have disturbances such as irregular heatbeats, they could develop them in future. But he stressed ''could''.

''We started to see [scarring] in the events that were over the six-hour mark,'' Dr Prior said. ''The people that we saw the scarring in had been doing [ultra-endurance events] the longest and had done the most number of these events. So maybe it's not good to do lots and lots of them.''