Michael Johnson 43.84
Otis Harris
Her first Olympics was in the 1992 Olympics which were held in Barcelona, Spain. she competed in the 4x400m relay and the team came in at 7th place
She won a silver medal in the women's 400m dash.
19.30
A 400m dash is 0.4km.
10.75
Milkha Singh who finished 4th in men's 400 meter dash. He missed winning a bronze medal by .13 of a second.
Michael Johnson (USA) set the 200 Meter Dash World Record at the 1996 Atlanta Olympic Games with a time of 19.32 seconds.
1km = 1000m so the 1500m only
Cathy Freeman participated in three Olympics (1992 in Barcelona, 1996 in Atlanta, 2000 in Sydney). She won two medals, a silver medal in the 400 meter dash in 1996 and a gold medal in the 400 meter dash in 2000.
2 and more up to 4
Alberto Juantereno from Cuba won the 400m and 800m at the Montreal Olympic Games in 1976.