Two men from Cambridge have been warming up for the race of their lives - 150 miles across the Sahara desert.
Paul Mathew (l) and Martin Fisher want to raise £10,000
Martin Fisher and Paul Mathew will run the equivalent of a marathon a day, every day for six days, in temperatures of more than 40 C.
On Thursday they fly out to Morocco for the race which starts on 9 April.
They will have 20 pints of water a day for drinking and washing and will have to carry a week's supply of food in their 10kg packs.
They both work for Fauna and Flora International in Cambridge and are hoping to raise £10,000 to help save endangered species.
They will be among the 610 runners taking part in the 19th Marathon des Sables.
A specialist medical team of 31 doctors and nurses will look after the health of the participants who are advised to cover their heads to avoid sunstroke and heat exhaustion and run in loose-fitting cotton.
But it is their feet which are going to take the biggest pounding, so daily blister treatment will be routine.
Both men, who have been training independently for eight months for the challenge, say they are looking forward to the race.