Nick Grimshaw has rejoined a Sport Relief challenge in the Namib Desert after being forced to pull out due to heat exhaustion.

The BBC Radio 1 DJ was able to reunite with his celebrity teammates on the gruelling challenge – which involves a 100-mile trek across the tough terrain by bike, foot and ski – following a day of rest and after undergoing a thorough medical assessment from support crew on the ground.

Grimshaw had been unable to continue with the challenge on Monday and was forced to drop out of a 35-mile cycle on medical advice.

The broadcaster, who said he was “absolutely gutted” about having to pull out, also missed Tuesday’s 24-mile leg of the journey on foot.

However, he is now able to continue for the penultimate day of the expedition and, along with his teammates, will scale 19 of the highest sand dunes in the world on foot and skis in temperatures exceeding 40C.

Grimshaw, 35, is on the expedition with Frankie Bridge, Karim Zeroual, Louise Minchin, Rob Rinder, Krishnan Guru-Murthy and Samantha Womack.

The challenge aims to “help break down the stigma of mental health and raise money for mental health services”, Sport Relief said.

Halfway through the skiing challenge on Wednesday, BBC Breakfast presenter Minchin said: “There’s hardly any shadow at all and it’s only 10 O’clock in the morning.

“I’m looking across miles and miles of the world’s biggest sand dunes and they are so high. We’re taking on 19 of them today.

“We’ve been talking a lot about why we’re doing it and we’ve all individually got a reason that we’re doing it.

“It’s hard. It’s relentless. But it’s utterly incredible being in the middle of nowhere in such a beautiful place.”

Channel 4 journalist Guru-Murthy said that “it’s been absolutely horrific” so far.

“It’s been far more shocking than any of us thought it would be,” he added.

“It’s been genuinely really difficult. Everything is 10 times harder because of the heat. But it is utterly stunning at the top of the dunes. You need to stop and take it in.”

Former Saturdays singer Bridge said she finds it easier to take part in the trek in the early morning.

“When it’s cloudy and cooler I find it easier but by 8.30am it’s already roasting,” she said.

She added: “I just want to get as far as I can, in my own time and at my own pace. I did have a moment arriving in camp last night when I thought, this is just amazing. I’ve surprised myself today.

“I really hope my experience in the desert shows people with mental health issues that you can still do the things you want to do.

“There have been times that I’ve wanted to give up but I’ve somehow managed to push through.”

The team are hoping to have crossed the desert by Thursday on foot, bike and ski.

Their efforts in the Namib Desert will be broadcast in an hour-long Sport Relief documentary on Wednesday March 11 at 8pm on BBC One.