Kaylee McKeown has found the perfect way of getting over post-Olympic boredom -- by getting back to training and helping herself to another world record.

Australia's great Olympian admits it's not been easy coming down from the ultimate high of striking double gold in Paris last month as she found herself twiddling her thumbs back home on the Gold Coast and feeling a bit bored.

But less than two months since reaping a five-medal haul at the Games, she found the ideal answer by returning to training and then annexing a new short course world record in the 100m backstroke just a couple of weeks later on the opening night of the national championships on Thursday.

McKeown's 54.56 seconds mark at South Australia's Aquatic and Leisure Centre outside Adelaide comfortably eclipsed the previous record of 54.89 seconds, set by fellow Australian Minna Atherton in Budapest five years ago.

"It's great ... the Olympics has been a huge whirlwind and something I never thought I would be able to achieve," said the 23-year-old backstroke queen, who now has five Olympic golds to her name.

"People don't realise just how much of a high it is and then to come back down again. It has been a struggle, and I have been pretty open with that, but I'm here swimming, so it's making me a bit happy.

"I had some solid downtime after the Olympics and only decided to do the short course at the last minute.

"I was going a bit stir crazy, sitting at home, so decided to jump back in two and a bit weeks ago, and just increasing the sessions.

"I don't mean to toot my own horn, but we're doing some pretty incredible stuff at training."

So incredible that, off the back of scant preparation, McKeown recorded the fastest 100m in history in a 25-metre pool to now own the long-course world records in the 50m and 200m back, and the short-course marks in the 100m and 200m.

Last October, she had become only the second swimmer to hold all three backstroke long-course records - 50m, 100, 200m - simultaneously until Regan Smith broke the 100m back mark at the US Olympic Trials in June.

But McKeown has a chance to add another record to her growing list when she goes in the 50m backstroke on Saturday. It may be an outside shot, although nothing seems beyond her.

Still, though, McKeown hasn't decided yet whether to shoot for more international bullion in the short-course worlds in Budapest in December.

"I'll see how I feel after World Cups (in October/November) and see if I want to do World Short Course in December, but I'm not putting any pressure on myself."