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The 4x100 meter relay has been included as a men's event in all Olympic Games since 1912, and as a women's event since 1928. The United States has dominated both events throughout Olympic history, with men's teams taking 15 out of 25 gold medals, and women's teams have won 11 out of 21 golds. The world records and Olympic records were all set in the 2012 Olympics; the men's were set by Jamaica, with a time of 36.84 seconds, and the women's records were set by the United States, with a time of 40.82 seconds. The most successful athletes in the 4x100m relay are the U.S.' Frank Wykoff, who won three back-to-back golds between 1928 and 1936, and the U.S.' Evelyn Ashford, who also won three back-to-back golds between 1984 and 1992.

Why are athletes faster in the relay?

If the men's world record of 36.84 seconds in the 4x100m is divided by four, then it shows that each runner had an average time of 9.21 seconds per 100 meters. This is 0.37 seconds faster than the current 100m world record set by Usain Bolt in 2009. Possibly even more surprising, Bolt's record time in the anchor (final) leg of the 2015 IAAF World Relays was 8.65 seconds (0.93 seconds faster than his world record). In running events at the Olympics, the 4x100m relay has the fastest speed of any men's or women's event. The reason for these record times is because only one of the runners starts from a stationary position, while the other three runners in the team are allowed to build up speed before they hit (close to) their top speed and take over the baton. The men's world record is also faster than the world record for the individual 400m race by more than six seconds.

How the relay works

Athlete's run in teams of four, with the starting runners beginning in staggered blocks, using the same specifications as those used in the 400m. The runners then sprint for 100 meters before exchanging the baton with their teammates. The exchange takes place in a thirty meter zone that overlaps both athletes' 100 meter stretch; in this zone, the receiving runner will use the first ten meters to accelerate and build up momentum, before the runners exchange the baton. The exchange is usually done "blind", where the receiving runner looks forward as they begin building momentum and then stretches their receiving hand backwards, before the incoming runner then passes the baton to the receiver. Smooth exchanges are fundamental to completing the race in the fastest time possible, and if teams drop the baton, cross lanes or exchange outside of the designated zone then they are disqualified from the race. These disqualifications are common even at the highest level, for example, in the men's relay in 2016 the United States were disqualified as the first baton exchange took place outside the designated zone, while Trinidad and Tobago were disqualified for a lane infringement.