The Vitruvian Triathlon – the national long distance championships – has attracted a field of 1,000 athletes.

Competitors will be challenged to swim 1,900 metres through the cold water of the reservoir from 6.20am.

After completing that leg of the race they will leap into the saddle and cycle 84km, including two climbs over the notorious Rutland Ripple.

Racers will have climbed a height of 1,000m by the time they are ready to finish the event off with a 21km run around the reservoir.

One of the organisers, Mark Shaw, said: "The Vitruvian is fast becoming a legendary race within the triathlon community.

"In 2007 we received over 1,000 entries for a race limit of 800.

"This year we have increased the limit to 1,000 and we fully expect to have all the places filled."

Hundreds of spectators lined the route last year and crowd figures are expected to be just as big this weekend.

The swim section starts immediately in front of the Harbour Bar Cafe at Whitwell.

Competitors, who will complete two laps of a triangular course, will be on staggered starts with the last wave of swimmers setting off at 7.10am.

The bike route has been changed from previous years because of the new Oakham bypass.

Cyclists, who pedal two laps of a 42.5km course around Rutland Water, make the transition from the bike to the run at Whitwell.

They then face a run to the finish, taking in landmarks such as Norman ton Church en route.

The finish line is in front of the cafe at Whitwell.