<P> Pacemaking gained much usage after Chris Brasher and Chris Chataway successfully paced Roger Bannister to break the four - minute mile for the first time in 1954 . </P> <P> Purists argue that employing pacemakers detracts from the competitive nature of racing . Original rules frowned on a competitor who was not actively trying to win, and pacemakers were required to finish a race for any record to count . This rule has now been dropped, though the pacemaker must still start with the other athletes in the race as a registered entrant . A lapped competitor may not act as a pacemaker . </P> <P> The 1500 metres at the Bislett Games in 1981 became part of track folklore when star athletes including Steve Ovett chose not to follow pacemaker Tom Byers but race among themselves . Ovett's scintillating last lap was not quite enough to catch Byers, who held on to win by a few metres . A similar case occurred in the 1994 Los Angeles Marathon when veteran marathoner Paul Pilkington was paid to set a fast pace then drop out . When the elite athletes failed to follow his pace, he kept going, ultimately winning $27,000 and a new Mercedes to the surprise of the expected favourites . That year, the L.A. Marathon was the National Championship race, so he also became the United States National Champion . Also Brazilian Vanderlei De Lima, marathon's bronze medalist in Athens 2004--famous worldwide for being attacked by a spectator while leading the men's Marathon--was originally a' rabbit' at Reims Marathon 1994, the first marathon he ever raced and where he was supposed to be a rabbit up to the 21 km point, and won . </P> <P> Pacemakers are also used in horse racing, where mediocre horses may be entered into major races specifically to set the pace for superior horses from the same stable . On a few occasions, pacemakers have finished ahead of the horses they were setting the pace for, such as when Summoner won the 2001 Queen Elizabeth II Stakes, and At First Sight running second in the 2010 Epsom Derby ahead of his two more - favoured stablemates . </P>

Why do they have pacemakers in london marathon