An intrepid scientist who took athletes to the extremes of human endurance says the lessons learned could help save the lives of everyday people.
Professor Damian Bailey, visiting New Zealand for a series of talks this month, has been there for freediving attempts tens of metres below the sea and expeditions to some of the highest peaks on the planet.
The University of South Wales physiologist's action-packed career has focused on the complex nature of how oxygen is transported to the brain in the most testing conditions.
Read more: Q&A: Extreme scientist Damian Bailey
These insights could tell us more about the causes of brain impairments such as stroke and dementia and potentially offer alternative ways of preventing or treating them.
The former international footballer and endurance athlete has helped British Olympic athletes to boost their performance at altitude, climbed with athletes up a 6500m peak in Bolivia and has advised Nasa and the European Space Agency.
Two months ago, he was the lead scientist on an expedition to the summit of Mt Everest, which British adventurer Richard Parks wanted to reach without supplemental oxygen.
"The purpose was to showcase the effects of extreme altitude on the body and by exploring why low blood oxygen levels cause impaired mental agility and its relevance to dementia in later life," said Professor Bailey, who will be speaking at the New Zealand International Science Festival in Dunedin next week.
In doing so, he was seeking to take the world's highest recorded measurements to understand how the brain communicated with the heart, lungs and muscles.
"I also examined what happens during acclimatisation and why the brain's performance improves - not just the body's - as it sees more oxygen and what lessons can be translated into the clinical setting," he said.
But the expedition was cut short just as the team was about to progress to the Khumbu Icefall, where it would have been too dangerous for Parks to have further acclimatised without oxygen.
"I took blood samples from Richard and it became clear that he was making way too many red blood cells," said Professor Bailey.
"Though this is a natural response to the lack of oxygen and is an important part of acclimatisation, Richard's blood became so thick that it became a risk factor increasing his susceptibility to stroke or throwing off a clot."
He noted the contrast in danger between that mission and the one by New Zealand's most famous adventurer, Sir Edmund Hillary, when he and Sherpa Tenzing Norgay became the first to reach the mountain's summit on May 29, 1953.
Hillary's equipment was comparatively heavier and his clothing less insulated, meaning his oxygen cost and risk of cold injury were greater, but above all, the feat itself had not been attempted before and the physiological demands were simply unknown.
"The psychological stress would have been far greater compared to today," Professor Bailey said, "since there were many doubting Thomases within the scientific community, fearing that the summit was beyond the limits of human tolerance."
With the exception of a successful summit without oxygen first achieved in 1978 by Reinhold Messner and Peter Habeler, today's climbers were "simply standing on the shoulders of these giants".
Professor Bailey felt the research was crucial, particularly as patients faced low levels of oxygen as a result of numerous diseases affecting the brain, heart and lungs' circulation - something which was especially evident in patients in intensive care.
"However, they face a whole range of other challenges - we call them co-morbidities - and this can muddy the water inasmuch as cloud to what extent the lack of oxygen itself is causing problems."
Professor Bailey said improving our understanding of the mechanisms that limit human tolerance to oxygen deprivation could lead to the development of new target therapies that could ultimately save lives.
Science on the edge: Professor Damian Bailey in his own words
"I'd like people to understand that we have evolved with brains that are oversized, inefficient gas guzzling energy hogs and that create a problem whenever blood supply is challenged either by disease or other environmental challenges." - on our brains
"More oxygen means better quality of life; and exercise is a cheap, safe and effective tool to help with this." - on the benefits of more oxygen reaching the brain.
"Rugby union is a fantastic example of two opposing forces that challenge the brain; the good of exercise which helps the brain develop and the bad of impact which over time, can actually take over the benefits and cause long-term complications." - on rugby and its physiological pros and cons
"Extreme models have indicated that the female brain is better able to cope with the lack of oxygen at high-altitude, much to the chagrin of the macho male counterparts." - on how oxygen demands at high altitude vary between women and men.
Professor Damian Bailey is a guest of ADInstruments from July 11 until July 22, hosting a series of guest lectures in NZ. He's also a guest at the NZ International Science Festival and will appear on a panel at Dunedin's St David Lecture Theatre on July 13. For tickets see www.scifest.org.nz.