In Canberra for a two-week training camp, swimmers are required to spend at least 14 hours inside the house to reap the benefits. The other 10 hours of each day are filled with training, eating or commuting.

Queensland's Chelsea Gubecka is a veteran inside the house after taking part in last year's camp. While the hours can tick by slowly, she said the effects of altitude training more than make up for it.

"I know what keeps me sane and what not, and in the scheme of things it's not a long time," the 17-year-old said.

"We have to get one hundred hours up in the house, and while we really enjoy our outings when we get them, we have a good time in the house too.

"I absolutely notice a difference after being in the house - it increases your red-blood cell count and that really helps when we are chasing an aerobic gain."

Men's 10km swimmer George O'Brien is experiencing the effects of the altitude house for the first time, and said he was finding the added stress on the body a challenge.

"I'm finding it's effecting my recovery between sessions a lot more, your body has to work hard while you're up in the house and that obviously corresponds with what you're doing in the pool as well," O'Brien said.

"When you come out of the house - for some people there's a really flat period, I tend to find I do get that - but when that passes you really feel quite good in the water and it speeds everything up."

Gubecka burst on to the open-water scene as a 14-year-old at the world championships in Spain, finishing 30th in the open water 10km swim.

She's now on the long road towards Rio de Janeiro and the 2016 Olympic Games. She will swim at the Aquatic Super Series in Perth in early February to trial for a spot in the Portugal Olympic qualifier in May.

Swimmers are competing for just one Olympic spot for each sex. Gubecka is in pole position for the women's spot after she finished 13th at the World Championships in Kazan in July. She said the Olympics remained the No.1 hope.

"It's a hope, we're not there yet," she said. "There's still a few more steps to take and there's a lot of swimming between now and the trial."

National open-water head coach Ron McKeon said this week's training camp was essentially the start of a long training bloc which would climax at next year's Olympic Games.

"Any opportunity to bring endurance athletes together is a great motivation and great stimulus for them, so to be able to come down here and use the AIS as a focus point is great," McKeon said.

"This is about resetting and stimulating the swimmers enough to be able to head home and progress from there."