Fitness instructor Nathan Taylor is preparing to run a staggering 10 marathons in 10 days to raise money to send a brave little boy to America for life-saving treatment of a rare disease.

Mr Taylor, 27, will run alongside a network of rivers and canals for more than 260 miles from the Thames near Swindon to Wigan to help the appeal for Callum Kaye reach its goal.

The six-year-old Swindon youngster has a severely malignant brain tumour that cannot be treated in Britain where surgeons last year said he had around 12 months to live.

But his parents tracked down a specialist centre in New York that could save his life and require an initial £175,000 to book the youngster a place before his condition is beyond treatment.

Boosted by a series of community events, the fund is currently at around £150,000 but, say appeal organisers, has stuttered as a result of the credit crunch.

Mr Taylor is now hoping to push it closer to £175,000 so that Callum's parents, Craig Kaye and Anna Eagle, can book the flights and clinic.

Mr Taylor said: "I'm absolutely determined to finish 10 marathons in 10 days. I'll do it even if I have to walk or crawl there."

Mr Taylor, who works at JJB gym in Swindon, heard about Callum's Appeal through his brother Carl and decided to embark on an unusual feat of endurance to raise cash for the stricken youngster.

He said: "It just seemed like an incredibly important appeal and I felt I had to do something. I just want to raise as much as possible.

"I'm looking for corporate and individual sponsors. It's so important to get this money for Callum."

He plans to run 26.2 miles for 10 days on the trot from the Thames at Lechlade on November 3 to his employers' HQ at Wigan via Oxford, Shropshire, Liverpool and Leeds. Yesterday, Callum's Appeal spokesman Oswin Holladay said: "It's fantastic for Nathan to be doing this.

"The appeal has been fantastic but has slowed a little of late because of the credit crunch. We had hoped to send Callum to the States before Christmas but now it looks like the New Year."

Callum, of Penhill, Swindon, was in 2006 diagnosed with the rare brain tumour condition medulloblastoma.

Surgeons removed 80 per cent of the tumour, but chemotherapy failed to shrink the rest. Six months later, they did a scan and found the cancer had spread down the youngster's spine.

After being told no more could be done with NHS treatment, his parents found that special techniques were administered at New York's pioneering Memorial Sloan Kettering Cancer Centre.

Now they hope experts will remove what is left of his original tumour and flush the rest of the cancer from his body.