Complex sentence: In May 2011 De Williams became the first female to run continuously around Australia and broke Sarah Fulcher's record for the longest continuous run by a female, running 18026.4 km in 408 days.
Split into simpler sentences: In May 2011 De Williams became the first female to run continuously around Australia. She broke Sarah Fulcher's record for the longest continuous run by a female, running 18026.4 km in 408 days.