Edinburgh man in fastest pensioner Gobi desert crossing
As the most diversified course of the 4 Deserts Race Series combining a cooler weather mountain trail race and a hot desert race, The Gobi March in China is one of the world's most gruelling running races.
Competitors must carry all the food and bedding they need over the seven days it takes to cross the 155 miles (250km) through a landscape of pastures, river beds, steep sand dunes and rough Gobi terrain.
The temperatures get so hot during the day a Shanghai-based competitor died of heatstroke in the 2010 race.
Edinburgh runner Donald Sandeman was the first pensioner to complete this year's race, coming 33rd overall.
The 60-year-old suffered crippling heatstroke during temperatures that were well over 47C (118F) and had to have huge amounts of sand removed from the inside of his ears after enduring a night in a sand storm when his tent blew away.
The retired police officer lost all his toenails and admitted he was worried for his safety when he was unable to cool down during the double marathon day.
The ultramarathon runner had to scale 500ft (150m) sand dunes while wearing a heavy pack and suffered very painful blisters on the soles of his feet.
However, despite 13 competitors being forced to drop out due to the extremely harsh conditions, Mr Sandeman crossed the finishing line on Saturday.
Speaking from Chengdu in China, Mr Sandeman told the BBC Scotland news website, he lost a stone in weight during the race.
He said: "This was a tough race. Climbing some of the sand dunes was like running up a downward travelling escalator and with a heavy pack you had to be very careful not to fall backwards.
"The heat in the camp was 47C and hotter in the desert outside. On the longest day I was really worried as I got heat stroke and just couldn't cool down.
"I was shivering and passing out. I just couldn't get enough water into my body and I became concerned for my safety.
"I found a rock to hide behind but I just could not cool down.
"By the evening it was still 41C and getting to the next camp was like a death march.
"When I finally got to the next camp at 01:30 I fell down and slept. I'm a very light sleeper normally but I was just so tired that I didn't wake up even when I was being sand blasted during a sandstorm when my tent blew away."
The race takes place in Hami region in the eastern part of Xinjiang Province in China in the area of the ancient Silk Road.
It follows the Tian Shan Mountains, one of the largest mountain ranges in Asia, and crosses the mountain range on Stage 2.
Mr Sandeman has completed over 100 marathons and ultramarathons.
Elaine Sandeman, 59, Donald's wife, who was marshalling and a sweeper for the race, said she was very proud of her husband's achievement.
She said: "The heat was unbelievable. You could see heat waves rolling over the sand and could imagine water.
"I didn't know he had heat stroke but heard he was stopping at all the roving points as well as the checkpoints so knew something was up.
"I was very glad to see him although he had dropped back in the field. The race was pretty hard generally with lots of hills however the last double stage was the killer.
"Five people dropped out that day including one of the lead guys.
"The checkpoints were carnage with runners lying about.
"They made a three hour rest compulsory in the middle of one of the days, which some runners originally complained about but everyone realised that it was the best thing to do and probably saved their race if not their lives.
"I'm used to him doing daft stuff so I don't worry unnecessarily or I would be in an institution by now."