United States Olympic Trials (track and field) fill out the field. Since 1972 there have been a minimum of 24 entries in any event, with the popular sprint events 100 meters, 200 meters, 400 meters and 110 meter hurdles having a minimum of 32 entries. Since 1992, athletes achieving the "A" standard are funded to attend the Olympic Trials, while "B" standard athletes have to pay their own way to the meet. Unlike many other countries, who have a selection committee, the selection to the United States Olympic Team is exclusively by results on the track. It's "do or die" in the prescribed event. If two or
800 metres have been known to use a negative split to their advantage. A positive split is achieved by running the first lap faster than the second lap, and a negative split is achieved by the opposite, running the second lap faster than the first could help. The current world record holder, David Rudisha, runs using a positive split strategy. In his 2012 Olympic race, he ran his first lap in 49.28 seconds and his second lap in 51.63 seconds. Theoretically, an even split is the most effective strategy, but it is nearly impossible to achieve due to the race's length. As