Maybe not so much "secrets" as that these things just...don't...interested people beyond a casual curiosity. If it doesn't make money for someone, why bother?
Below is a story from the NY Times (the link no longer is active, so I had to cut/paste from a file I kept) describing some Belgian researchers who tried to hypothesize why Nepalese porters and women from certain African tribes are able to bear very heavy loads on their heads or across their foreheads without expending the amount of energy that one would logically assume you'd expend during such tasks.
They are totally clueless, scientifically. They attribute the "strength" of the porters and water carriers to their short stature, frequent rests, the way the tump line (carrying strap) of the Nepalese is used across the forehead (but they don't elaborate on how that would work), and a greater number of oxygen-bearing red blood cells that typically develop in all human beings who live at high altitudes for some period of time. At no time does any knowledge of biomechanics or even mechanical engineering (structure) come to bear in their studies! They also forget that the African women are not living at high altitudes, might be relatively tall, and that they carry the jugs of water on their heads, not necessarily with tump lines.
In a post a month or two ago, Mike Sigman made a really sensible postulation about the African water carriers and such load bearers, noting that a jin path to the ground was the most likely reason for their amazing abilities. It's not magic, and it's not even "rocket science." It's knowledge of structure and load-bearing, as well as the human body's ability to make maneuvers to maximize those elements. But not a soul in the science world seems to have investigated the structural physics and the biomechanics of it.
It would be a great thesis for a master's or Ph.D. in exercise physiology, physical anthropology and a number of other areas. Personally, if I had the energy to go back to grad school and finish my degree work in primate evolutionary ecology, I'd do it myself. But except for the Belgian researchers, no one else seems to have even a bit of curiosity about this peculiar phenomenon that seems to fly in the face of normal human function.
So, I don't expect too many people to get excited about other aspects of internal skills, either.
BTW, I would consider the activities below to be a perfectly fine demonstration of some of the internal skills Justin would like to see. I've been to Nepal four times, and many times have seen tiny, elderly Nepalese women carrying 75 lbs. of firewood on their backs with tump lines, trotting up steep Himalayan trails while I (a very fit hiker at the time) was left in the dust. I guess what fascinated me more, was that these old ladies and young girls were doing virtually all of the heavy load carrying while their menfolk sat in the tea shops and played cards.
The Times June 17, 2005
Why the sherpas of Nepal would leave our fittest soldiers standing
By Mark Henderson, Science Correspondent
NEPALESE mountain porters who climb steep Himalayan slopes carrying more than their bodyweight are the fittest and most efficient load-lifters in the world, scientists have found.
Their combination of technique and physical ability makes their performance far more effective than that of Western soldiers marching with backpacks, according to research. It even surpasses the most efficient carrying methods studied to date: those of African women whose loads are balanced on or suspended from the head.
A study by Belgian researchers has quantified the remarkable efficiency of Nepal's porters, most of whom come from the sherpa, Rai or Tamang ethnic groups, for the first time. They carry huge loads in a basket known as doko, which is supported with a strap looping around the top of the head.
A team led by Norman Heglund of the Catholic University of Louvain, in Brussels, conducted tests on eight porters travelling to a bazaar in the town of Namche, which lies 3,500m (11,500ft) above sea level close to Mount Everest.
The dirt-track route from the Kathmandu Valley to Namche covers 62 miles (100km), with combined ascents of about 8,000m and descents of about 6,300m, and takes seasoned porters between seven and nine days to complete. Hundreds of porters make the trek every week; on the day before the bazaar, the scientists counted 545 men and 97 women, along with 32 yaks, with many more passing earlier and later in the darkness. The youngest porter was 11 and the oldest 68.
All were carrying loads that seemed unfeasibly heavy to Western observers. The men bore an average of 93 per cent of their bodyweight and the women an average of 66 per cent. A fifth of the men were carrying 125 per cent of their bodyweight and one managed an astonishing 183 per cent.
By contrast, the greatest loads carried by African women, such as those of the Kikuyu tribe in Kenya, amount to 60 per cent of bodyweight, and the loads typically included in military backpacks are lower still.
Dr Heglund, whose results are published today in the journal Science, recruited eight of the porters for further investigation, which has shed some light on the nature of their amazing skills. The porters were asked to walk along a 51m flat track at five different speeds, carrying six or seven different loads, while their oxygen intake and carbon dioxide output was measured.
The tests revealed that loads of up to 20 per cent of bodyweight were carried "for free" — meaning that the porters' metabolic rate did not increase at all compared with an unladen walk. With higher proportional loads, their energy efficiency was far greater than seen with the most efficient head-based carrying techniques used in Africa.
Previous research comparing Kikuyu women with army recruits found that the former carried heavy loads much more efficiently. For loads of 20 per cent of bodyweight, Kikuyu oxygen consumption rose 2 per cent compared with 13 per cent for the soldiers. The difference was even greater for 70 per cent loads: the soldiers used 100 per cent more oxygen, but the women only 50 per cent more. The porters did even better. While they were not subjected to quite the same tests, they were able to carry an extra 30 per cent of bodyweight, on average, while maintaining the same metabolic rate.
Their secret seems to rest on three factors. The first is physiology: the combination of a short but powerful stature and a high red blood cell count evolved as a result of living at high altitude. Also critical is their carrying technique, by which a strap around the head bears the majority of the load. The final element seems to be the regular rests that they take during their climbs.
TAKING THE STRAIN
Technique: doko basket on the back supported by namlo strap around head
Load and efficiency: male porters carry average of 93 per cent of bodyweight, females 66 per cent. Maximum was 183 per cent. Can carry 100 per cent of bodyweight for same energy used by an African woman carrying 70 per cent
Technique: loads balanced on the head or suspended from it using straps. The most efficient method, used by the Kenyan Kikuyu, uses bindings across the forehead to support a load on the back
Load and efficiency: Loads do not generally exceed 60 per cent of bodyweight
Technique: backpack with shoulder and waist straps
Load and efficiency: US Army guidelines say that a backpack should weigh no more than 15 per cent of a soldier's weight. A 70 per cent load raises oxygen consumption 100 per cent