The longest distance run three legged in 12 hours is 77.3 km (48.03 miles) and was achieved by Gary Shaughnessy and Andy Tucker (both UK), in Silchester, Berkshire, UK, on 24 September 2023.
https://www.guinnessworldrecords.com/world-records/longest-distance-run-three-legged-in-12-hours
https://www.justgiving.com/fundraising/gary-shaughnessy2?fbclid=IwAR3yfx3fFNW_DqnDJUTxctP_jPzchvOyKxwMES6ADmp4AL9MF8NlVuVHTd8
