Richards could only took bronze in the Beijing Olympics, but she has been the fastest in the world this year. She posted an impressive time of 50.05 seconds to take first.
There were few surprises in the men's event.Olympic men's 400m champion LaShawn Merritt was comfortably a step ahead of the rest of the field as he powered to an impressive win on his birthday.
2004 Olympic gold medallist and two-time World champion Dwight Phillips took the title with a leap of 8.57 metres in the men's long jump.
