Interesting Article on High Alt Adaptation

[Peter_Puget]

Web link

 

High-Altitude Breathing May Be in One's Blood

 

By Guy Gugliotta

Washington Post Staff Writer

 

Monday, December 23, 2002; Page A09

 

 

The mathematics are inescapable. The higher the altitude, the less oxygen

the air will hold, and the more difficult it is to breathe. Either the body

adapts, or the person dies.

 

For decades scientists accepted an "Andean man" model for acclimatization:

The body at altitude will grow a higher concentration of oxygen-absorbing

red blood cells to mop up scarcer oxygen from rarified air.

 

Add bigger lungs and deeper breathing, and equilibrium is reestablished. The

result is a blocky fellow with a washtub chest, like the musicians who play

the panpipes and wooden flutes of Andean mountain music.

 

"Their lungs are 25 percent bigger than ours," said Case Western Reserve

University anthropologist Cynthia Beall. "Andean highlanders are very

distinctive."

 

Earlier this month, however, Beall and five colleagues reported on another

distinctive people -- a community of Ethiopians who live at 11,650 feet, and

whose blood, by several common measures, is exactly the same as if they

lived at sea level.

 

"I'm flabbergasted; I don't see how they do it," said exercise physiologist

David Martin of Georgia State University. "I'm left with a dozen questions.

It's a fascinating kind of story."

 

And it is not just a curiosity. For Martin, a consultant for USA Track &

Field, and others like him, the extraordinary success of African distance

runners -- principally Ethiopians and Kenyans -- has been a source of wonder

ever since barefooted Abebe Bikila won the 1960 Olympic marathon. Is there a

secret that others cannot possess?

 

"Efforts to find a genetic explanation have been dismal failures," said

Dallas cardiologist Ben Levine, an expert in exercise medicine. "My personal

opinion is that these successes are cultural. A distance runner in Ethiopia

or Kenya is a national hero."

 

In an online article to be published in the Proceedings of the National

Academy of Sciences, Beall's team reported on 300 people living in the

Semien Mountains about 300 miles north of Addis Ababa. Testing showed they

had neither elevated red-cell concentrations nor low levels of oxygen

saturation in their blood -- two key indicators of the Andean model.

 

"We were stunned," Beall said. "The Ethiopians are finding the same amount

of oxygen we find, even though the amount of oxygen in the air they breathe

is two-thirds of what we have at sea level."

 

Humans transport oxygen via hemoglobin, a protein in red blood cells that

binds to oxygen molecules and moves them from the lungs to muscles and other

tissues. At sea level, between 95 and 97 percent of the body's hemoglobin is

saturated with oxygen during every breath.

 

At altitude, reduced oxygen logically means lower oxygen saturation. In the

Andes, highlanders compensate by producing more red cells to create a

heightened "hemoglobin concentration" -- a higher proportion of red cells in

the blood. That way the blood has more hemoglobin to sponge up scarce

oxygen.

 

Lowlanders need at least 10 days for this process to begin. In the meantime,

however, they will acquire the other characteristic of high altitude

survival -- deeper and more frequent breathing. The Andean barrel chest

comes from being born and raised at altitude.

 

Scholars were satisfied with this explanation until studies in Tibet in the

1970s showed that highlanders there had both low hemoglobin concentrations

and low oxygen saturation levels. In theory, the Tibetans should have been

oxygen-starved.

 

"But they breathe faster, and there's also some evidence that they are

better able to modulate blood flow," Beall said. "When they exercise, their

blood flow increases more rapidly, so they may have a larger cardiac output.

We don't really know."

 

The Himalayan research triggered a debate over a possible evolutionary

explanation for high altitude adaptation. The Andeans, whose lowland

ancestors migrated from Asia perhaps 16,000 years ago, adjust to altitude

essentially the same way as any lowlander would today -- and it is not a

perfect solution.

 

"Creating more red cells is a pathological response," said Temple University

anthropologist Charles Weitz. "If you have too many red cells, the blood's

too thick, and it's like pumping oil. Eventually you have to move downhill."

 

Tibetans or their ancestors, however, have been in Asia for 1 million years

or more -- time enough, some scholars theorize, to evolve a different

approach.

 

Exercise physiologists were moving along a different track. Realizing that

ultra-high hemoglobin concentrations were no good for athletes -- syrupy

blood doesn't flow well -- they still sought enhanced athletic endurance by

increasing red cell counts, but only in the context of a larger overall

blood volume.

 

"Over time -- four weeks minimum, or many months -- you can elevate both red

cells and volume, therefore keeping [sea level] hemoglobin concentrations,"

Levine said. Athletes with this training have hearts that "pump more blood."

 

So why is it that the Andean nations -- except for Colombia's cyclists -- do

not produce more such athletes? There is no scientific answer, but Georgia

State's Martin suggests that many Andeans may "live too high -- 12,000,

13,000, 14,000 feet" -- so high that "the blood turns to sludge."

 

Altitude training seeks to expand the competitor's blood volume using a

combination of lowland workouts and highland living, varying the amounts of

time in each milieu. Finding the optimum times and altitudes is a Holy Grail

of athletic trainers.

 

In Ethiopia, the two tracks may converge. Human ancestors first arose there

and in Kenya as much as 4 million years ago. If Darwinian adaptation has

played a role, there may be no likelier places.

 

Ethiopia and Kenya are also countries where the runners come from high

altitudes, but not too high: Ethiopia's Haile Gebrselassie, who holds the

world's 10,000-meter record at 26 minutes, 22.75 seconds, lives at 7,900

feet in Addis Ababa, and trains in the surrounding hills.

 

In the Semien mountains, Beall's team tested people of all ages, mostly

herders with no particular athletic bent. Unlike the Andeans, their

hemoglobin concentrations were the same as those of lowlanders. But unlike

the Tibetans, they also had high, sea-level oxygen saturation levels.

 

Beall does not know how this can be, but her team did not look at blood

volume, which might at least explain the hemoglobin concentrations: "If

Ethiopians have a bigger blood volume, they could do a better job of

transporting oxygen," Martin said. "If an athlete in Ethiopia has this huge

blood volume, he's going to have an enormous advantage at sea level."

 

 

 

[Norman_Clyde]

This is extremely interesting. Just when you thought we knew everything about exercise physiology... but that part about running success in E. Africa being cultural is not true, in my opinion. Some physical types are better at distance running than others. If the researchers can figure out how they squeeze more oxygen from the same thin air, I hope they can also figure out how to pass on the advantage to the rest of us.

[texplorer]

Norm, I respectfully disagree with you and believe that the advantages the kenyans and ethiopians posess is genetic. I ran against those bastards in college and some of them are some sick athletes.

[eternalX]

Well, it's probably a combination of both. The genetic mutations that allow for this were probably caused by where they lived. If this tribe has lived there for several hundred years, then their bodies have adapted to the altitude, which COULD be reflected in their genetic code.

 

Also, happy get drunk day