for National Geographic News
If you've ever watched Nepalese porters in action, you might think they have superhuman strength. How else to explain their ability to carry loads weighing more than 100 pounds (45 kilograms), mile after arduous mile over steep Himalaya terrain?
Now scientists say they have a clue as to how the porters do it: They use less energy than other people would require for the same work.
Norman Heglund, a physiologist at Catholic University of Louvain in Belgium, led the study, which was sponsored in part by the National Geographic Society Committee for Research and Exploration.
Twenty years ago Heglund studied African women in Kenyawho often balance loads atop their headsto investigate their unique burden-bearing efficiency.
His latest study, which appears tomorrow in the journal Science, now suggests that the porters of Nepal are even more efficient at their tasks. Precisely why, however, remains a mystery.
So legendary are the load-carrying abilities of the Nepalese that the word Sherpa, a term for one of the country's ethnic groups, has become synonymous with "porter."
A typical Nepalese porter carries a load nearly as heavy as he is. When he does, the porter burns less energy per pound than a backpacker would need to shoulder about half the same weight, Heglund and his colleagues found.
That remarkable ability helps porters to earn a living carting goods great distances between markets in the Himalayan nation. A weekly bazaar in the market town of Namche, for example, serves a gathering point for merchants from all over the Mount Everest region.
"Often, you see husband-and-wife trekking teams," Heglund said. Porters stock up on goods in the Kathmandu Valley and carry their loads from dawn to dusk over the course of a week or more to reach Namche, which sits at 11,500 feet (3,500 meters).
En route, the porters traverse more than 60 miles (100 kilometers) along rugged footpaths. During the journey, they climb some 5 vertical miles (8 kilometers) and descend about 4 miles (6.5 kilometers).
After the porters sell their goods in Namche, they race home unencumbered for more cargo.
"They literally run down the mountain," Heglund said. "They can get home in about two days."
SOURCES AND RELATED WEB SITES