The Radio 1 DJ, Nick Grimshaw, is to cycle for 12 straight hours for Sport Relief on Monday.

Nick's challenge forms part of an attempt from BBC Radio, as a collective,to run, swim and cycle 25,000 miles – the circumference of the world – all in support of Sport Relief.

Velorution, the BBC’s local cycle shop based just steps away from the broadcaster’s central London base, has supplied equipment for Nick’s epic ride, inside a Perspex box on the plaza outside New Broadcasting House, open to the public.

Starting at 7am, Nick will cycle an Eastway FB2.0 on a turbo trainer for twelve straight hours.

Nick’s leg of the challenge starts in his Breakfast Show at 7am and finishes in Greg James’ Drive Time Show at 7pm the same day.

Radio 2’s Jo Whiley will take on an even more brutal assignment of her own, and attempt to run for a full 26 hours in the Perspex box.

She will start her arduous treadmill mission at 8pm on Wednesday 19th March while presenting her Radio 2 show, and finish at 10pm at the end of her show the next day – having run through the night.

Here's the box in which Whiley and Grimshaw will be undertaking their challenges:

Nick said: "It's amazing to be doing a tough challenge for Sport Relief – although the last two times we've done sport on the Radio 1 Breakfast Show, there have been injuries. So hopefully this will be third time lucky."

Last month we reported how Davina McCall wept with exhaustion for the last time in a while as her gruelling 500-mile Sport Relief triathlon came to a climactic end in London.

The 46-year-old Big Brother presenter ran a full marathon as the last leg of her Scotland to London dash over a week.

The presenter has already raised more than £760,000 via her Sport Relief page, with the money going towards projects for maternal health in Kenya and charity in the UK.