Metrication in the United States traditional mile-based lengths. In the Olympics, athletes run 1500 meters, not 1600 meters. Running races in the U.S. are usually run in metric distances (e.g., the 100 metres dash or the 5K run), although the mile distance remains popular. But even 5 and 10 kilometer races most often have mile markers on the course, and no kilometer markers. Long-distance races are often measured in kilometers, although exceptions exist (generally 10 mile races). The marathon is referred to as a 26.219-mile race (the official marathon standard distance originally being in English units — 26 miles, 385 yards) rather than 42.195 km.
IAAF World Half Marathon Championships IAAF World Road Running Championships. Aside from the name change, the significant difference was the distance of the race, changing from a half marathon to a 20 kilometres road race. The 20 km race featured only at the 2006 edition, and the half marathon distance returned for the 2007 World Road Running Championships. On 29 November 2007, the IAAF announced that the name of the competition would revert to its original title of the IAAF World Half Marathon Championships, beginning with the 2008 IAAF World Half Marathon Championships in Rio de Janeiro, Brazil on 12 October 2008. This competition should