Kevin Sinfield has announced he will embark on a fifth fundraising challenge for motor neurone disease charities in December – and has invited Prince William to join him.

The rugby league legend will run seven ultramarathons across seven different cities in seven successive days, a repeat of last year's successful '7 in 7 in 7' endeavour.

Sinfield has already raised more than £15million for MND causes since his friend Rob Burrow was diagnosed with the neurodegenerative disease in 2019.

The former Leeds Rhinos team-mates were awarded CBEs by Prince William in a special ceremony in their old dressing room at Headingley in January.

And asked if he would encourage the future King to put on his trainers and take part in his upcoming challenge, Sinfield said: 'He's more than welcome to join us at any point!'  

Kevin Sinfield said his fifth fundraising challenge for MND charities will start in December

Sinfield's latest fundraiser will start in Liverpool on December 1 and take him to Wales, Northern Ireland and Scotland, before returning to England and finishing in his home town of Saddleworth on December 7.

The 43-year-old will run more than 30 miles each day and will break each ultramarathon into hour-long 7km legs – another nod to Burrow's former Rhinos shirt number.

'When you are passionate about something, it's really easy to go again,' said Sinfield, who is stepping down as defence coach of the England rugby union team after this summer's tour to Japan and New Zealand.

'There will come a time when people are completely sick of us which is fine, but we still want to help, so why should we stop?

'To see the fight in Rob and the inspiration he has given so many people across the UK, it has been incredible to be a part of.

'I always bring it back to we are just trying to help a mate, and our team are really passionate about that.

'We will run at least 50km a day in a variety of cities across the UK and bang that drum for MND.

'We will run each hour in 7km slots to give us time to meet the MND community and that's what this has been about for the last four years.'

Sinfield's first challenge for MND charities was in 2020, when he completed seven marathons in seven days around Oldham and Leeds. The following year, he ran 101 miles from Leicester to Leeds in under 24 hours.

In 2022, he completed seven ultramarathons in seven days, starting at Murrayfield and finishing at Old Trafford. Last year, he did the same but in different cities, starting at Headingley and then finishing on The Mall in London.