Complex sentence: His horses were named Champion Female Turf Horse on four occasions and in 1986, at the age of seventy-three, he became the oldest trainer to win the Kentucky Derby then won again three years later.
Split into simpler sentences: His horses were named Champion Female Turf Horse on four occasions. In 1986, at the age of seventy-three, he became the oldest trainer to win the Kentucky Derby then won the prestigious trace again three years later.