 The IAAF keeps world records for five different types of track relays . As with 4 × 100 m and 4 × 400 m events , all races comprise teams of four athletes running the same distances , with the less commonly contested distances being the 4 × 200 m , 4 × 800 m and 4 × 1500 m relays . Other events include the distance medley relay ( comprising legs of 1200 m , 400 m , 800 m , and 1600 m ) , which is frequently held in the United States , and a sprint relay , known as the Swedish medley relay , which is popular in Scandinavia and held at the World Youth Championships in Athletics programme . Relay events have significant participation in the United States , where a number of large meetings ( or relay carnivals ) are focused almost exclusively on relay events . 
 The IAAF <a href='uninflect' title='1'><mark>keeps</mark></a> world records for five different types of track relays . As with 4 × 100 m and 4 × 400 m events , all races comprise teams of four athletes running the same distances , with the less commonly contested distances being the 4 × 200 m , 4 × 800 m and 4 × 1500 m relays . Other events include the distance medley relay ( comprising legs of 1200 m , 400 m , 800 m , and 1600 m ) , which is frequently held in the United States , and a sprint relay , known as the Swedish medley relay , which <a href='drop_aux' title='2'><mark>is</mark></a>popular in Scandinavia and held at the World Youth Championships in Athletics programme . Relay events <a href='got' title='3'><mark>have</mark></a> significant participation in the United States , where a number of large meetings ( or relay carnivals ) are focused almost exclusively on relay events . 
Da IAAF keep world records fa five different types of track relays . As witt 4 × 100 m and 4 × 400 m events , alll races comprise teams of four athletes running tdasame distances , wid thdaess commonly contested distances being theda× 200 m , 4 × 800 m and 4 × 1500 m relays . Other events include the distance medley relay ( comprising legs of 1200 m , 400 m , 800 m , and 1600 m ) , which is frequently held in the dated States , and a sprint relay , known as the Swedish medley relay , which popular in Scandinavia and held at the Wdad Youth Championships in Athletics programme . Relay events got significant participation in the United States , where a number of bigass meetings ( or relay carnivals ) r focused almost exclusively on relay events .