You’re swimming in scorching hot temperatures, desperately trying to acclimatise to the sweltering heat as you plough through the water. The humidity is so heavy that it’s a real effort to take a breath, but the current in the water is increasing.
Meanwhile someone else is standing in what can only be described as bitter Arctic weather. The temperature is going down to minus 20 degrees Celsius and it’s so raw it feels like it’s biting against their skin.
It may seem as if these two environments should be on opposite sides of the planet, but in fact they are recreated in two spaces just metres away from each other in a laboratory at the University of Portsmouth.
They are part of the Extreme Environments Laboratory in the Department of Sports and Exercise Science.
Run by Professor Mike Tipton, who’s the director of research for the department, it’s one of the most internationally-respected laboratories of its kind.
Mike says: ‘Our work looks at the physiological and psychological responses in extreme environments. We can recreate in these facilities just about any environment on Earth.’
He adds: ‘We want to find ways of deterring the body’s responses to those environments.’
Mike and the technicians who run it have worked with the BBC, the RNLI, the Ministry of Defence and UK Sport.
Placing people in extreme environments helps to prepare them for anything they might be facing, whether it be for work or play.
The team have researched people’s ability to adapt to heat and cold, the prediction of survival time in cold water, the thermal impact of protective clothing, stress and psychological profiling.
Their work has also ranged from assessing bicycle helmet performance to spotting casualties on a beach scene.
The laboratory is made up of three different chambers called Golden, Pinsent and Fiennes.
The Golden and Pinsent chambers can have an air temperature of up to 50 degrees Celsius, with one holding a four-metre swimming flume with underwater windows, while the other has a 4.5-metre immersion pool. The water temperatures can go as low as four degrees.
The Fiennes chamber, named after the world-famous explorer Ranulph Fiennes who has used it for training, can have an air temperature as low as minus 20 degrees, which is as cold as Antarctica.
Mike says: ‘The two immersion facilities also include cold water for anybody who has to work or play on the water, over it, or under it.
‘All of the chambers can go up to 8,000 feet in altitude too, so we can look at things like responses to altitude when going on expeditions.’
The team has worked with a number of industries who face uncertain environments every day, including oil companies and the military.
They’re also the designated thermal laboratory for both UK Sport and the Fuchs Foundation charity.
Mike says: ‘Extreme environments have a significant impact on all aspects of our lives. For example we help support athletes as they need to become acclimatised to different environments for their sports.
‘We look at people and athletes who perform in hot environments. In the run-up to the Olympics in Rio de Janeiro, Brazil and the World Cup there, athletes and footballers will have to prepare for the drastic change in environment.’
He adds: ‘But it’s not just about sport. It’s right across the spectrum. We may sit in a sports science department, but it’s a reasonably small percentage of what we do.’
Speaking about others the lab is involved with, he explains: ‘We have companies that provide protective clothing and the military are often involved in activities in extreme environments, whether that be cold or hot weather.’
But it’s not just professionals who need to use the equipment at the laboratory. Many individuals like to take on expeditions that will challenge them physically and mentally.
Mike explains: ‘The great British public like to engage in weather-based activities. There are 20 million on a regular basis enjoying some form of outdoor activities.
‘But some of those people get into trouble and might find themselves drowning. In the UK, we lose between 400 and 700 people a year and one child a week on average.
‘This is the worst time of the year because the general temperatures are heating up, but the water temperature is still very low.’
Mike says entering cold water should be done with caution.
He has been involved in new research that has resulted in scientists warning that entering cold water suddenly, without taking time to acclimatise, may cause abnormal heart rhythms that can be fatal.
While the whole of the UK is gearing up for next month’s Olympics in London, Mike’s team are already looking ahead to four years’ time in Brazil.
He says: ‘For the 2012 Olympics we don’t need to worry about extreme environments, but we are working and looking ahead to Rio de Janeiro and researching for that.
‘We were involved with athletes when they were getting ready for the Beijing and Athens Olympics.’
They also work with many local groups involved with protecting individuals in the water, such as the RNLI, the Gosport and Fareham Inshore Rescue Service and the Maritime and Coastguard Agency.
Mike says: ‘In terms of where we would want to have an extreme environments lab, Portsmouth is a good place because there’s a combination of lots of people who work and play in the extreme environments and also there’s the military.
‘There’s a lot of information exchange going on locally as well as nationally.‘
A host of famous faces have been to the laboratories at the University of Portsmouth to prepare themselves for personal challenges.
Explorer Sir Ranulph Fiennes has used the laboratories a number of times and even has one of the chambers named after him.
Comedian and author David Walliams prepared in Portsmouth for his swim across the Channel in 2006 for Sport Relief,
TV presenter Alice Roberts trained at the lab for an hour-long documentary for BBC Four called Wild Swimming.
Blue Peter presenter Helen Skelton used the facilities when she trained for her South Pole challenge for Sport Relief earlier this year.
Meanwhile top triathlete Alistair Brownlee used the chambers to help him prepare for the Beijing Olympics.
Kevin Fong, who previously worked for NASA and has appeared in TV presenting roles, used them in his Back From The Dead TV series in 2010.
Explorer and ex-rugby player Richard Parks also used the chambers when preparing for his 737 Challenge to climb the seven highest peaks in the world.
And TV presenter Ben Fogle and Olympic rower James Cracknell both came to Portsmouth in 2009 to prepare for a race to the South Pole.
Long-distance open water swimmer Anna Wardley, who lives in Gosport, has been into the Extreme Environments Laboratory chambers several times to help students in their research.
She says: ‘I was asked to take part in a study they were doing about how the body responds to cold water. They wanted to compare people that were acclimatised and those that weren’t.’
Anna’s experience of the chambers has opened her eyes to how important the team’s research is.
Anna adds: ‘I think what they do is extremely important because they are protecting people by looking at the long-term effects of cold temperatures on the body.
‘They’ve done lots of work with the RNLI and helped to develop the knowledge that can help save lives. It’s great to have this facility in Portsmouth.’