BBCA 66-year-old man has completed 200 marathons in 200 days around the British coastline.
Retired banker Steve James travelled 5,240 miles (8433km) since setting off from Topsham, Devon in April, and returned there to finish his challenge on Saturday.
Researchers at the University of Exeter monitored the impact on his body throughout the journey.
Mr James said: “I haven’t had a day off in seven months so I’m quite looking forward to the prospect of a lie-in and not having to complete 26 miles tomorrow.”
‘Seven pairs of trainers’
Despite finishing strong and without injury, Mr James, who lives and trained on Dartmoor, said it had been “quite the challenge”.
He faced harsh weather conditions, closed footpaths, severely-blistered feet, and a gout flareup which resulted in a trip to the emergency department.
He has been sharing updates throughout the challenge on his social media pages.
“I’ve survived storm Floris and storm Amy, been through seven pairs of trainers, become a state pensioner and climbed the equivalent of Mount Everest ten times,” he said.
“But it’s just shown me that you’re never too old to take on something huge.
“You’ve just got to start and keep going.”
Mr James took daily measurements for researchers and they studied his calorie intake, energy expenditure and body composition to monitor the impact the high-endurance challenge had on his body.
Nutritional physiology researcher Dr Freyja Haigh said they had not seen a detriment to Mr James’ overall health from the fortnightly blood samples he sent to them.
“The body measurement changes suggest that Steve’s weight loss is a result of fat rather than muscle which is a positive result to see after such a long time in an energy deficit,” she said.
“It will be interesting to see just how much muscle Steve has maintained when we get him back in the lab for post-challenge tests.”
She added it had been a privilege to work with Mr James, and his efforts gave them “valuable knowledge about the body’s ability to cope with the demands of such extreme endurance”.
