Almost half of Australia's best athletes are earning below the poverty line threshold with an annual income of less than $23,000.

That's the finding from the Australian Sports Foundation, which warns that without bolstered financial support the country risks an exodus of top-tier talent ahead of major international events.

Two in three elite Australian athletes aged between 18 and 34 have considered quitting their sport, a survey by the foundation found.

One in two athletes aiming to compete in the 2026 Commonwealth Games have weighed up leaving their sport, as have 43 per cent of those working towards the 2032 Olympic Games in Brisbane.

More than 40 per cent of them were financially worse off than a year ago, and more than one in four experienced a decline in their mental health in the past 12 months, the foundation found.

"This is the green and gold decade with so many such events for us to look forward to, but they are nothing without the athletes," foundation chief executive Patrick Walker said.

The elite adult athletes surveyed were earning an average annual income of between $23,000 and $49,000.

However, 46 per cent of them earned less than $23,000 a year from all their income streams combined, the foundation found.

The biggest challenges were costs and financial insecurity, with elite athletes spending more each year on travel and accommodation for competitions than they did on food.

Very few received financial support through fundraising or a sporting body, Mr Walker said.

Champion swimmer Bronte Campbell said the biggest costs she racked up through her career were injury-related, and while injury support was brilliant when it was there, costs soon started to outweigh the support received.

Athletes had to contend with financial pressures specific to them as well as pressures affecting the broader community including rent and mortgage prices, she said.

"If you win an Olympic gold medal, you get a medal bonus - which is not, as someone once asked me, a million dollars," Campbell said.

"It's a lot less than that. But trying to support yourself in between Olympics and in between times when you're having those high performances.

"There's definitely been years where if I hadn't had success in the previous year, I don't know how I would have made it work."

Mr Walker urged Australians to consider donating to their local athletes and sporting clubs given government funding alone wasn't enough.

He also encouraged athletes to look for other revenue streams.

The Australian Olympic Committee was also working with the federal government and Australian Sports Commission to develop a sport investment model, chief executive Matt Carroll said.

There is currently a $2 billion shortfall in federal funding, he said.

"As we look to the future, particularly Brisbane 2032, we cannot afford to see these inspiring young athletes walk away from their dreams," Mr Carroll said.

The Australian Sports Foundation's findings were based on a survey of more than 2300 Australian athletes, including more than 600 athletes at the elite national or international level.

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