MOST of us would find one marathon hard enough to tackle but how about seven? Oh, and let's do them on all seven continents - on seven consecutive days!

Dr Mike Stroud was part of the first team to walk unaided across the Arctic ten years ago - but his latest challenge is set to upstage even that feat.

The nutrition expert from Southampton General Hospital will be putting his own health to the test when he teams up again with international explorer Sir Ranulph Fiennes in a bid to run seven marathons on seven continents in seven days.

Dr Stroud is taking part in the challenge to raise money for the British Heart Foundation and Southampton-based medical research charity Hope.

Starting in Antarctica on October 26, the pair will then run in Santiago in Chile, Sydney in Australia, Singapore, London, Egyptian capital Cairo and finally in the New York marathon on November 2.

Dr Stroud, who, together with Sir Ranulph, made the first unaided walk across the Arctic ten years ago, decided to have another go at the challenge at the beginning of the year.

The 48-year-old father-of-two, who lives in Liss, east Hampshire, said: "Ranulph rang me up saying did I want to climb Everest, but that was too much time off work and away from my family, so I said did he want to try the marathons?

"We decided we would do it as soon as was practical, which was as soon as the Antarctica winter was over.

"Then Ranulph had a heart attack and had to have a heart bypass operation and I didn't think he was going to be able to do it. But he recovered very quickly from it and said he wanted to have a go."

The pair, who hope to raise tens of thousands of pounds for charity, have been taking part in various marathons across the country to prepare themselves for the event, including last weekend's Clarendon Way marathon, which started in Winchester.

Dr Stroud said he was fairly confident they would be able to complete the challenge, but added they would just try their best.

He said: "It's a very difficult thing to do. We think we might be able to do it, but at the same time there's always the threat of injury."

Money raised from the challenge will be split between the British Heart Foundation and Dr Stroud's own work on the nutrition of patients in hospital, funded largely by Hope.

Ring Hope on 023 8033 3366 to find out how to sponsor Dr Stroud.