There are two types of ultramarathon events: those that cover a specified distance or route; and those that last for a predetermined period of time (with the winner covering the most distance in that time). The most common distances are 50 kilometres (31. 069 mi), 100 kilometres (62. 137 mi), 50 miles (80. 4672 km), and 100 miles (160. 9344 km), although many races have other distances. The 100 kilometers is recognized as an official world record event by the International Association of Athletics Federations (IAAF), the world governing body of track and field.