With a little more than 1,000 days to go until the 2020 Tokyo Olympics begin, preparation - even at this stage - is key, BBC reports. 

Such is the case with American swimmer Dana Vollmer, who claimed her seventh Olympic medal in Rio last year.

But she has had to adapt her preparation for Tokyo to cater for, in her words, the "bowling ball" in her stomach.

In her first race since Rio on Thursday, Vollmer was six months pregnant.

The first obstacle was finding a swimming costume that worked for her - up from the size 26 she wore in Rio to a size 32 at Thursday's race in Mesa, Arizona.

"It kind of holds everything in," she said, in an interview on the Team USA website. "We had to go up a few sizes to hold the belly."