Epic race across France tests runners' stamina
22 August 2013 Last updated at 14:08 BST
While it may not be as famous as cycling's Tour De France, the country's Trans Gaule running race provides another stiff test of human endurance.
The race, which covers almost 1200 km (746 miles), is spread over 19 days and sees runners embark on a gruelling trek from France's north coast down to the Mediterranean south coast.
Participants are expected to reach the finish line on 31 August.
Tom Bayly reports.