From the article Dave cited:
.... On average, the [Nepali] men carried nearly 90 percent of their body weight. A quarter of them carried more than 125 percent of their own weight, according to the new study, which appeared in the Journal of Experimental Biology. The heaviest load, Heglund says, totaled 175 percent — or nearly twice as much as the porter's weight. The porters in the study weighed between about 100 and 140 pounds.
The women carried an average of 70 percent of their weight – a good 10 percent more than the heaviest of loads carried by women in the African studies.
Compared to the muscles of European graduate students, the study found, the porters' muscles were slightly more efficient at turning oxygen into work. But there was nothing unusual about their gait or energy use.
Thanks so much for your contribution Dave; that is an interesting study.
I am not surprised by the weights they found, but I, and others more knowledgeable than I- do not agree with that last sentence. I've shared the trails with mountain porters in Asia for about 2,000 miles, and I definitely agree with the author of the best trail guide to Nepal, who is also a doctor, when he described the differences in the porter's gait and hiking method. For instance, he noted, and I definitely noticed, the porters smooth, bent-kneed, feet placed flat, gait on downhills. Their packs seem to float, they are so stable. Porters gait in general was supremely controlled. Slow, steady, balanced movement that serves to keep the huge load perfectly in sync with the body's movement. Also, there is very little heel to toe rocking in their gait- I am reminded of that book Hobbes is into-
Born to Run, which documents the natural, and quite different from ours, running style of native runners such as the Tarahumara.
Like Dave implies above- their secret may be how they pace themselves so perfectly. They know how not to burn out. All along Nepal's trails, there are many high bench rest stops, where the porters can back in and rest their packs. This is because it is so dreadfully difficult to lift those size loads from the ground- it would tend to blow out the knees! Porters in Nepal also carry a stout, 'T'-shaped staff which they deftly place under their load to rest from it. They stop to rest a lot!
There is also a subtle something which might escape a researcher who is a physician first, and a hiker second, that most of us old hiker cats have learned long ago. That is, the simple, but so important fact that every damn misstep and trip wastes a ton of energy. So the fact that experienced porters have learned to walk with such control, actually translates into much greater ability to carry heavy loads long distance. Isn't it true, that the heavier the load, the worse it is to trip with it? A boxing analogy is the fact that to miss with a heavy punch takes so much more out of you than to connect with the same punch, or to just miss with a jab. The physiology of this is that in both cases- the backpacker who trips, or the boxer who misses, they are thrown off balance, and it takes a lot of energy to recover the balance.
This is part of my problem with the statement below:
there was nothing unusual about their gait or energy use.
It is something very special to be able to cruise along trails in good balance, and it isn't so easy. Balzacom, you would be well placed to tell us about the gait of novice hikers that you have taken out. Don't you think the reason they get tired and sore so soon is that they misstep and stumble so frequently? Anyway, it's a fascinating subject to me; thanks for the post. Ian.