Complex sentence: She debuted at the age of 19 at the Los Angeles Summer Olympics in 1984 where she won her first gold medal in the double scull event and she won her most recent gold medal in the Eight oared boat at the Athens Summer Olympics in 2004.
Split into simpler sentences: She debuted at the age of 19 at the Los Angeles Summer Olympics in 1984 where she won her first gold medal in the Double Scull event. She won her most recent gold medal in the eight-oared boat at the Athens Summer Olympics in 2004.