Two runners who took part in an ultra-marathon in the Sahara desert have spoken about the extreme conditions.
Nathan Walton, from Woore, Shropshire, said the drop-out rate was three times that in typical years as competitors battled through 50C (122F) heat.
Shaun Marshall, a postman from Kidderminster in Worcestershire said: “Humans don’t belong there, they don’t belong in that environment.”
Both entered the Marathon Des Sables to raise money for hospices.
The 156-mile (251km) series of races across the Sahara desert lasts six days, but Mr Walton said the course changes every year, and this year many of the stages were longer.
He said normally up to 10% of the runners drop out, but this year it was about 30%.
“Every day they were withdrawing or being pulled out,” he said. “It was quite distressing to see.”
Mr Walton admitted he had been struggling since he finished on Saturday, but said: “I just take a look at the fundraising page and see those donations come in and it’s all well.”
He has so far raised more than £11,000 for the Dougie Mac Hospice in Staffordshire.
“I now understand why they call it the world’s toughest footrace and I’ll never do it again,” he said.
Mr Marshall said since coming home he felt ecstatic, but also “numb and a little bit hollow” because he did not want to stop.
He also said it was “probably the hardest thing that a human can do”.
The sand dunes had been like “walking through muddy water,” he said.
“Once you get to the dunes you are up to your knees and they are relentless,” he said.
At night, between runs, he slept under a goat skin tent, using his rucksack as a pillow.
Those taking part have to carry everything they need as they run, and Mr Marshall said it was the thought of those worse off than him that kept him going.
He was raising money for Kemp Hospice in Worcestershire and for his colleague’s five-year-old grandson, Freddie, who has cerebral palsy.
Source : BBC