International Association of Ultra Runners IAU
The International Association of Ultra Runners(IAU) organises the World Championships for various ultramarathon distances, including 50K, 100K, 24 hours and 48 hours. These events are sanctioned by the International Association of Athletics Federations (IAAF), the world governing body of track and field. Many countries around the world have their own ultrarunning organization, often the national athletics federation of that country, or are sanctioned by such national athletics organizations. World records for distances, times and ages are tracked by the IAU.