From Hollywood to Holyrood - world's elite limber up in Edinburgh

The annual event kicked off yesterday with a "parade of nations" and opening ceremony outside the Scottish Parliament.

The duathletes were decked out in the home country's colours, as they paraded past the parliament and through Holyrood Park ahead of the first race at 2.30pm.

The event caused widespread traffic congestion around the area, however, with roads leading to the park closed off until Sunday morning.

Over the weekend, almost 1,000 competitors will each complete a duathlon circuit, involving a 10km run followed by a 40km cycle and then a 5km run, in the hope of being crowned world champion.

Edinburgh previously hosted the European duathlon championships in 2007, while the last world championships were held in North Carolina, in the United States.

The circuit consists of multiple laps around Holyrood Park and Arthur's Seat, close to the Scottish Parliament - said to be one of the most challenging ever used on the international circuit.

The event runs all weekend, where the athletes will compete for six world championship titles, 27 age group gold medals and a total prize fund of 62,600.

Catriona Morrison, former world and European duathlon champion, from Broxburn, West Lothian, hopes to grab the title once more, in front of a home crowd.

She said: "The chance to compete around Arthur's Seat is a once in a lifetime opportunity.

"It will be a really tough fight to see who's going to be crowned 2010 world champion."

She and her fellow Scotland and Great Britain participants were joined by athletes from across the globe, including Spain, Argentina, Brazil, Canada, New Zealand and the US.

Duathlon is a combination of two individual sports - running and cycling.

A typical duathlon consists of three stages.

It starts with a run, followed by a cycle section and finishing off with another run, all completed as a continuous activity.

There is a strong duathlon scene throughout the UK, including a British championships as well as Scottish and Welsh duathlon championships.