An ultramarathon (also called ultra running) is any sporting event involving running longer than the traditional marathon length of 42.195 kilometres (26.2188 mi).
There are two types of ultramarathon events: those that cover a specified distance, and events that take place during specified 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 (80.467 km) and 100 miles (160.934 km), although many races have other distances. The 100 kilometers is an official IAAF world record event.
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