A former international athlete spent his birthday running a marathon – in his six-metre-long back garden.

James Campbell spent his 32nd birthday running the 26.2-mile marathon course on Wednesday and took five hours and five minutes to complete more than 4,000 shuttles of his garden.

Mr Campbell promised to undertake the challenge if he got 10,000 retweets to his initial post on Twitter, having become bored while in lockdown at home in Cheltenham, Gloucestershire.

With the target reached in hours – with the likes of Premier League footballers Raheem Sterling and Michy Batshuayi retweeting him – Mr Campbell set up a justgiving.com page with a fundraising target of £10,000 for the NHS.

He smashed the fundraising target, with more than £17,000 raised so far.

Mr Campbell celebrated by jumping in the air and swigging from a bottle of beer.

During the run, Mr Campbell was cheered on by his mother from a neighbouring garden.

Speaking afterwards, he said: “It’s amazing. I realised pretty early on that it was only 6.4 metres if I ran in completely a straight line but every time I changed direction … I didn’t really take that into account so that’s why it went a little bit quicker.

“I absolutely blown away by the support and I was choking up a minute ago, it’s unbelievable. The amount of money it’s raised is absolutely incredible.”

Mr Campbell is a former world class javelin thrower and was a youth footballer with Cheltenham Town as a teenager.

After injury ended his athletic career, he returned to football and now plays for Hellenic Premier League team Brimscombe & Thrupp.

While at home bored, he decided he would run the marathon in his back garden having decided it was the most “stupid” thing he could do – and would do it if he got 10,000 retweets.

Within hours he had smashed the target and set up a fundraising page to raise money for the NHS.

Mr Campbell, who has never run a marathon before, said he expects to pay for it in the morning.

“I could feel my left knee was about twice the size about three-quarters of the way through,” he said.

“I don’t think anyone has much planned the next couple of days.

“It’s my birthday and it was going to be the most boring birthday in the world, where you can’t really do anything or see anyone or do this.

“So, the next couple of days I reckon I will wake up in a bit of discomfort but nothing compared to all the other people suffering at the moment.”

Mr Campbell now works in a gym owned by the grandson of 1966 World Cup hat-trick hero Sir Geoff Hurst.

“My athletics career didn’t really end as planned and this tops that by quite away,” he said.

“I have put myself through some pain during a very strange time for everyone, as long as it is for a good cause.

“If other people get inspired to do something like this, then good luck. I would recommend it, it’s not that bad.”

He has not ruled out further challenges if the lockdown continues.

“I’ll have to come with something else and see how bored I get in the next few weeks,” he said.

The fundraising page can be found at: https://www.justgiving.com/fundraising/james-campbell0104