Jonathan Woods says jumping into a bath full of ice for two minutes gives him the type of therapy and control he can never achieve with other forms of meditation.

"It sounds insane, I know," he said, through chattering teeth.

"I'm a very nervous person. This calms me."

Mr Woods follows the Wim Hof method — named after its Dutch inventor, it involves deep breathing and holding onto your breath while immersed in water as cold as one degree.

After a rough couple of years in his personal life, he tried medication, weightlifting and various meditation apps before being persuaded to give ice bathing a go.

Mr Woods says exercises help control the post-bath shivering. ( ABC Sydney: Amanda Hoh )

He got so much out of it, that last weekend he joined a retreat in the Snowy Mountains with a group of 30 people and hiked up a mountain to jump in the freezing Thredbo River for 13 minutes.

"You get to your most primal core at that point — I hear my mum's voice telling me I'm going to get sick, but it's about calming down and breathing through it.

"Once you calm down, you can stay there for awhile. It's a great feeling."

Changing the body

Guiding Mr Woods through his therapy sessions is Dutch-born instructor Johannes Egberts.

Mr Egberts has been living in Sydney for four years and is one of a handful of Wim Hof instructors in Australia.

Wim Hof participants stayed in the freezing Thredbo River for 13 minutes. ( Supplied: Johannes Egberts )

His morning ritual is to sit in a freezer tub of ice water for up to three minutes by getting himself into a trance-like state.

"It's quite simple but very powerful and effective," he said.

"One of the benefits is that you are expelling CO2 from the body ... you are starting to create this alkaline state.

"You're reducing the urge to breathe and it allows the body to go into states of hypoxia, or low levels of oxygen."

Mr Egberts acknowledged the practice of holding your breath could be dangerous, but urged people to do it in a safe environment.

He claimed there was little risk of hypothermia as the body "can cope" with such low temperatures.

Thrill of winter ice diving

Swimming throughout winter is a ritual for many, and an adrenalin-fuelled rush for others less accustomed to the bite of cold ocean water.

This weekend, hundreds of people threw themselves into Hobart's River Derwent for the annual winter solstice nude swim as part of the Dark Mofo festival.



Taking the icy plunge as a once-off activity won't have much effect on the body, according to University of Sydney exercise immunology lecturer Kate Edwards.

The annual winter solstice swim in Hobart gives swimmers an adrenalin rush. ( ABC News: Selina Ross )

But regular exposure to the cold, such as having a cold shower every morning in winter, could help you stay healthy, she said.

"Having regularly small stress responses is actually good for your body," Dr Edwards said.

"Exposures to stresses like that do help our bodies function better and cope with other things.

"From the science point of view, I do think it does help, but so does going for a run."

But there are risks

Followers of the Wim Hof method have been studied by scientists.

A report published in journal Proceedings of the National Academy of Sciences of the US, found the volunteers did change their sympathetic nervous system and immune system by releasing anti-inflammatory mediators.

What is hypothermia? Hypothermia occurs when body temperature drops below 35 degrees; normal body temperature is 37 degrees

Hypothermia occurs when body temperature drops below 35 degrees; normal body temperature is 37 degrees It can develop with prolonged exposure to temperatures below 10 degrees, or after prolonged immersion in cold water of less than 20 degrees

It can develop with prolonged exposure to temperatures below 10 degrees, or after prolonged immersion in cold water of less than 20 degrees Symptoms include feeling cold and uncontrolled shivering, fumbling hands, unsteady gait, slurred speech, confusion and drowsiness Source: NSW Health

Exercise physiologist Ben Taylor said he had tried the method and cautioned people doing it for the first time.

"For the regular person, [prolonged exposure to cold water temperatures] is not advised," he said.

"If you are going to stress the body out, you want to do it gradually, such as altitude training.

"Start with something small, like 30 seconds in a cold shower, and then over a period of time, slowly increase that time."

Mr Taylor said prolonged ice bathing or diving "is extreme", although the practice of moving the body between the cold and normal temperature can "help promote recovery" as it constricts and expands the blood vessels.

Both health professionals advised against ice bathing and cold showers for people with cardiovascular risks.