BY the time he lines up for the Plusnet Yorkshire Marathon on Sunday Rob Duddington will already have run 74 miles.

The 26.2-mile race is not enough of a challenge for this “ultra” athlete, so Rob has designed his own extreme running challenge, starting at 4pm the day before and running through the night until he reaches the finish line on Sunday.

Rob, 40, is aiming to run 100 miles, non stop, in around 22 hours.

“I do ultra events and I’ve always been better suited to long distances. I like events where it’s not about going for a particular time, but it’s something to get through.”

When he got a place on the Yorkshire Marathon, Rob decided to make it his most gruelling race ever – 100 miles is almost 50 percent further than he has run before – and use the marathon as the last leg of his challenge.

“I thought ending with all the other marathon runners would be a special feeling,” he said.

He leaves Hull at 4pm on Saturday and will run along an old railway line to Hornsea, along the beach to Bridlington and on to York, passing along parts of the marathon route before he heads back out toward Stamford Bridge with the rest of the runners.

He hopes to arrive at the university campus in Heslington between 5am and 8.30am on Sunday.

“If I get there early I will be able to have a bit of a rest before starting the marathon, but it might actually be better to arrive later and just keep going.

“I am definitely nervous. This will be the furthest I have ever run. I know it will be hard.”

Rob lives in Bradnesburton near Beverley and works as an adult education tutor. He has been training on roads and tracks all over the county, as well as along the beach at Bridlington.

Throughout his challenge he will be relying on friends in a support vehicle to keep him fuelled up.

“I will meet them about every two miles and try to eat about 300 to 400 calories an hour. I won’t want to, but it’ll be a case of forcing myself.

“I eat a lot of energy bars and things like nuts and fruit. I expect to get through around 30 bananas in the whole thing.”

Rob will be running most of the 100 miles himself, but will be joined for the marathon and for stretches through the night before by various other friends, including his running mate Kate Hack.

Kate and Rob met in another running event in December, and have trained and competed together ever since.

He is raising money for Macmillan Cancer Support.

To support him go to justgiving.com/robduddington