RUNNING the equivalent of seven marathons in seven days would be enough for most people.

But Oxford heart consultant Tim Betts’s latest fundraising challenge will see him run 100 miles along the Thames, day and night – without stopping.

Father-of-three Dr Betts, from Beckley near Oxford, is no stranger to tests of endurance.

In 2012 he tackled mountains and waded through peat bogs while running the epic 190-mile Coast to Coast route from the Irish Sea to the North Sea.

That feat helped him raise £7,000 for the Oxford Heart Centre’s Heartfelt Appeal.

At the time the renowned cardiologist joked his adventure was part of a “mid-life crisis”.

But two years on and now 45, he is preparing for the Thames Path 100, again to raise funds for the Oxford Heart Centre’s Heartfelt Appeal.

He said: “The Thames Path 100 is a continuous point-to-point race starting at 10am on Saturday, March 23, from Richmond Waterfront, and stretching 100 miles to the centre of Oxford. I have never run 100 miles without stopping before and that itself will be a huge challenge.

"But like the professional runners who take part in ultra marathons like this, I will probably run at a steady pace for a few hours at a time, before slowing for 15 minutes to change my muscle useage, and then running again.”

Dr Betts will have to contend with sometimes rough terrain, eating and drinking on the go and running through the night.

He said: “I will be carrying a rucksack with food like peanuts and protein bars and drinks, and warm clothes, plus there are 14 aid stations situated along the route which I can pick food up at, and I will be wearing a head torch and bike lights on my body – so hopefully I will make it unscathed.”

Around 250 runners set off together in the Thames 100 but most become separated almost straight away.

Those who do not make the 50-mile station by 15 hours are pulled from the race, as are those who have not finished by 30 hours.

For the last 50 miles, runners can have a pacer – someone to accompany them through the darkness, delirium and fatigue.

Dr Betts said: “My wife Margaret, (45), will be joining me for the last five to 10 miles of the race, which will be great.”

The Oxford Heart Centre specialises in cutting edge heart treatment and therapies.

But its ongoing plans, including building a new, advanced echocardiography unit to help patients avoid heart surgery, require continued fundraising.

Dr Betts has three children Charlie, 13, Hannah, 11 and Georgie, nine, who will be at the Thames 100 finish line at The Queen’s College recreation ground, off Abingdon Road, South Oxford, on Sunday, March 24.