The river marathon races are characterized by a duration longer than two hours, with intermissions at predetermined distances depending on the route. In these intermissions the athletes make portages where the competitors carry their canoes in a foot race with a distance of about 150 meters, and then they resumes paddling.
Vescovi, Marco M.D.; Benzo, Serena M.D.; Bronzini, Daniele; Bruttini, Flavia M.D.; Mortara, Antonio; Nakou, Ioanna M.D.; and Vescovi, Monica M.D.
"Two days, two marathons: superman?,"
International Journal of Exercise Science: Conference Proceedings:
2, Article 11.
Available at: http://digitalcommons.wku.edu/ijesab/vol5/iss2/11