Jeremy Langdon

Jeremy Langdon, 43, a Sky Sports reporter from Teddington, is going all out for the Ultra category.

He will be well trained for the London Duathlon, as he has just completed a stage of the Tour de France! Competing for the fourth time, Jeremy is delighted there is a longer cycling element this year, although he dreads getting a puncture.

Alex Flynn

Alex will be taking part in the Ultra London Duathlon raising money for The Cure Parkinsons Trust (www.cureparkinsons.org).

Diagnosed with Parkinson’s Disease at the age of 36 (almost two years ago), he vowed to run 10 million metres (6,500 miles) by 2014 in a bid to raise a million pounds - £1 for every metre he completes - to fund research into a cure for Parkinson’s; a disease that affects millions of people worldwide.

Alex has already taken part in many events including the Marathon de Sables, becoming the first Parkinson’s sufferer to complete the event, the Grand Union 145 and Ridgeway 85.

He will be joining the London Duathlon after the London Triathlon on 7th/8th August and the Europe135, a 135 mile race across the Bavarian Alps at the end of August 2010. Alex is planning future events including 1,400 miles across Europe and over 3,000 miles across the USA

"In five years I won’t be able to do any of this, so I want to do it all now," he said.

Alex, who has two boys aged nine and 10, will add another 160,000 metres to his record if he completes the 100 mile course around Richmond Park on 12th September.

Jenny Cottle

Jenny Cottle, 52, from Twickenham signed up for the world’s largest Duathlon in London on September 12 after losing six stone last year.

She competed in her first Triathlon earlier this year, alongside her partner and friends and after completing that, Jenny set herself the London Duathlon as her next challenge.

She said: "Before the Triathlon I had not run since my school days and I couldn’t run for longer than two minutes at a time.

"A personal trainer organised a 12-week programme for me, and I managed my first 5k run in Bushy Park with him, only two weeks before the triathlon.

"I beat my 5km run time in the triathlon and then thought what next?

"Being so local, the London Duathlon is the obvious next stage - two 5k runs which are taking me to another level and the bike leg, which I love."

Jenny hopes not to run out of steam during the hilly sections of the course, however, her biggest worry is keeping hydrated.

"At present I don't have the courage to take the bottle out of the carrier when cycling," she added.