You need more than courage and resilience to complete extreme challenges. You also have to be humble and smart enough to undertake a cool, calm analysis of the limits and potential of the human body. Experienced adventurers understand that turning a grand plan into a reality requires intelligence, self-knowledge and a thirst for research, planning and analysis.

This is why Dr Mark Hines – an exercise physiologist and biomechanist – is so good at conquering extreme ultra-marathons in the most dangerous and challenging environments on Earth. Hines’s scientific expertise is an integral part of his success and a reminder to adventurers worldwide that extreme expeditions require extreme levels of research and preparation.

Hines has taken part in the 740km Yukon Arctic Ultra in -40°C temperatures, the six-day, 251km Marathon des Sables across the Sahara desert in 50°C heat, the grueling 254km Amazon Jungle Marathon, in 99% humidity and the Ultra a 222km, oxygen-starved slog across the high-altitude peaks of the Himalayas. Wherever in the world he travels, science provides the invisible scaffolding around which he builds his success.

Q: Is there anything you can do to manage the humidity of jungles like the Amazon?
A: ‘Humid conditions are the hardest to exercise in as you generate heat from muscle contractions but all of your normal systems for cooling down fail. The normal transfer of heat to the outside of your body doesn’t work as it is hotter on the outside. Sweat needs to evaporate on the skin and that creates an energy exchange, which brings a cooling effect. But in saturated air of humidity up to 100% that sweat doesn't evaporate so you just lose fluids with minimal cooling.’

‘It’s better to run at a reduced pace and stay in control of your body temperature, rather than overheating. I saw people hospitalised in the Jungle Marathon, and one guy had a coma induced because he got so hot it started causing brain damage – his control centres for managing temperatures stopped working.’

Q: How does the lack of oxygen in the high-altitude Himalayas affect your body?
A: ‘Cerebral oedema (an accumulation of fluids in the brain), pulmonary oedema (an accumulation of fluids in the lungs), acute mountain sickness, hyperthermia, hypothermia, frostbite, hyponatraemia, rhabdomyolysis and dehydration are the biggest problems at very high altitude. During the middle of the day the temperatures soar above 30°C and at night they plummet to below zero. Hence the problems are similar to those in the hot and the cold environments, coupled with the unique problems of very high altitude.’

Q: Can you train to perform at those high altitudes?
A: ‘For very high altitude, it can be useful to spend a month or so at high altitude to allow the physiological adaptations to take place, such as increased red blood cell count. However, during that time at altitude, you cannot train as well as at sea level, so your fitness actually drops. The best approach is some combination of exercise and rest at high, moderate and low altitude. At very high altitude like in the Himalayas the challenge is to keep making forward progress, despite severe limitations in physical capacity.’

Visit www.markhines.org for more information. Mark’s books on the Marathon Des Sables, the Jungle Marathon and the Yukon Arctic Ultra are available on Amazon