Quotes of the Day

Believing that the world was in danger of becoming "a homogenous mass," marathon runner Mary K. Gadams set up an adventure company in 1996. The outfit, RacingThePlanet, was designed to "take people to some of the last remaining remote areas" of the earth. But since 2002, Gadams has been asking her clients to do it the hard way — encouraging them to compete in seven-day, 155-mile (250 km) foot races through the arduous terrain, blistering heat and frigid cold of the world's four largest deserts. Known as the 4 Deserts Race, the event takes in the salt plains of the Atacama in Chile, the riverbeds and hills of the Gobi in China, the undulating dunes of the Sahara in Egypt and the icy flats of Antarctica. Participants can tackle all the deserts or just one if they choose. And while organizers provide water and lay on tents and bathing facilities each night, everyone is expected to carry their own food and other essential gear.

People from all walks of life compete. Some just want to cross the finish line, others want to win (the time difference between the front runners and the back of the field can be in excess of 50 hours by each race's end). Competitors range between 21 and 67 years of age and come from more than 130 countries. Often, families and groups of friends enter together. Sometimes, companies use the races as team-building exercises or charitable endeavors — Microsoft entered three top executives from their Seattle headquarters in this year's Gobi race, known as the Gobi March, to raise money for the Save the Children Foundation. But most, like 60-year-old American Robyn Metcalf, who has done two desert races, are there to "combine sports with the opportunity to see other parts of the world, while also meeting people who are extending their mental and physical boundaries."

Gadams' husband, retired banker Alasdair Morrison, has completed all 4 Deserts legs and finds personal growth in the wilderness. "These events put life into perspective in many ways," he says. "Your needs on the races are quite basic and there is a lot about everyday life that you see is superfluous."

Then there are the extremists. This year, three individual competitors set out to tackle all four legs in one calendar year, but already only two remain: 33-year-old South African physician Paul Liebenberg, who has a practice in Australia's remote Outback, and 45-year-old American professional runner and Ultramarathon Man author Dean Karnazes. "I am not a balanced individual," says Liebenberg frankly, "and I have found the only way for me to deal with the physical, and especially the emotional, demands of bush medicine in the Australian Outback is to push myself physically hard as well."

For Karnazes (famed for once having run 50 marathons in 50 consecutive days) the ultimate high comes from meeting indigenous peoples en route — the Bedouin in the Sahara; Kyrgyz, Mongolians and Uighurs in the Gobi; and Atacameño tribesmen in the Atacama. "Although there are vast cultural differences between the native populations and the racers," he says, "a smile seems to cut right through the divergence and unite us all."

The number of competitors on each leg of the 4 Deserts Race is strictly limited — up to 180 on the Gobi March, but capped at just 80 for the Atacama — so early registration is essential. While your fitness levels don't have to be tip-top (you can stroll the entire length of the course if you wish), you had better have deep pockets. Each leg in 2009 will cost you $3,100 to enter. For more information, visit www.4deserts.com.

• Alexandra Hamlyn