Switzerland's national exhibition, Expo.02, launched a sports event of truly terrifying proportions on Monday with the start of the Expo Gigathlon.

Former Swiss sports minister Adolf Ogi fired the starting pistol in Yverdon to send more than 150 athletes on a potentially impossible mission around Switzerland.

The Gigathlon is a race over 1,477 kilometres, divided into seven straight days and among five different sporting categories (swimming, mountain biking, road cycling, running and either inline skating or wheelchair racing).

Almost 10,000 athletes from 11 nations will be taking part during various stages of the race, but a crack squad of 157 men and six women are attempting to cover the entire course.

Incomparable scale

The scale of the Gigathlon makes comparisons even to other endurance events difficult, but it has been estimated that this week's race is equivalent to seven consecutive Ironman competitions.

One man who should know is American triathlon star Mark Allen. Having won the prestigious Ironman Hawaii competition no less than six times, Allen has no doubt about the toughness of the Gigathlon which he insists will be "harder than the Tour de France."

Switzerland's mountainous profile hardly helps - the 163 athletes hoping to make it all the way round will also have to negotiate climbs and descents totalling some 21 kilometres.

Punishing schedule

Each day the athletes will have until midnight to reach the stage finish line. If they leave it that late, though, they will have just five hours sleep before check-in starts for the following day's race.

"I can't actually imagine that any individual athlete will manage to reach the end," reckoned Swiss mountain bike star Thomas Frischknecht, who is set to start the team competition.

The athletes themselves, though, insist that the race is possible. Swiss favourite Urban Schumacher has already completed the entire course in training - albeit in two sections with a few days' rest in between.

"It should be possible," reckons the 38-year-old from Uster. "Above all, it's about getting the tempo right. There are some very steep bike sections and it will be important not to overload the affected muscles."

Wider public

While plenty of attention will focus on the men and women attempting to conquer the Gigathlon as a whole, the race's organisers are also emphasising the event's accessibility to the wider Swiss public.

As well as the week-long individual challenge, there are daily competitions and team categories. And for those not braving the Gigathlon itself, there are separate sporting events being organised in cities and towns along the route.

Following Monday's departure from Yverdon, the athletes head via Lausanne and Bern into the cantons of Valais and Ticino before turning around in Graubünden and heading back towards the Expo.02 site in Biel via Schaffhausen, Lucerne and Basel.

swissinfo with agencies

In compliance with the JTI standards

More: SWI swissinfo.ch certified by the Journalism Trust Initiative