Flax was born in San Francisco, California, and is Jewish. Flax is a two-time Olympic hammer thrower, who competed in the 1988 and 1992 Olympic Games. He competed in Track & Field as a student at Redwood High School, and began throwing the hammer for the University of Oregon in January 1982, and by June 1982 he won the USA Junior National Championships and competed in the Junior Pan Am Games in Caracas, Venezuela. Flax later went on to win two Pac-10 championships and the 1986 NCAA Championships, throwing seven personal records in nine throws and broke the NCAA record three times in the process which still stands today as the American Collegiate Record.
After college, Flax went on to compete in three World University Games winning a bronze and in 1991 he won the gold medal, beating the former number one ranked hammer thrower in the world, Heinz Weis. One of the highlights of Flax's throwing career was competing in the 1987 and 1991 World Championships, where he finished 7th in 1991 marking the first time in 21 years that an American has made the finals in the hammer throw in a non-boycotted major world event.
In 2009, Ken was inducted into the Redwood High School Athletic Hall of Fame. Flax was the best field man in Redwood’s track history, a powerful young teen who hurled the shot 57 feet—second all-time best in the MCAL. He has also been inducted into the University of Oregon Athletic Hall of Fame.
|Representing the United States|
|1985||Maccabiah Games||Ramat Gan, Israel||1st||68.34 m|
|1986||Goodwill Games||Moscow, Soviet Union||10th||73.44 m|
|1987||World Championships||Rome, Italy||20th||73.36 m|
|1988||Olympic Games||Seoul, South Korea||18th||72.70 m|
|1989||Maccabiah Games||Ramat Gan, Israel||1st||78.06 m|
|World Student Games||Duisburg, West Germany||3rd||75.86 m|
|1991||World Championships||Tokyo, Japan||7th||75.98 m|
|World Student Games||Sheffield, England||1st||76.46 m|
|1992||Olympic Games||Barcelona, Spain||23rd||69.36 m|