In response to my recent article, Dr. Michael Joyner, Professor of Anesthesiology and an exercise physiology researcher at the Mayo Clinic in Minnesota. Over the last 25 years Dr. Joyner has published hundreds of scientific papers, and in 2011 received a Fulbright Specialist Grant., I received an email from
Dr. Joyner views on the reliability of exceptional performances have appeared in Runner’s World, and he has co-authored numerous papers concerning the sport of distance running, such as How Low Can Marathon Times Go in the journal Conversation and Modeling: Optimal Marathon Performance on the Basis of Physiological Factors.
After sending me a 2012 paper published in The Journal of Clinical Investigation that delved deeply into the subject of the body’s physiological adaptation to altitude, I asked Dr. Joyner if he could explain in more layman’s terms how altitude adaptation might help explain the current statistical gap between altitude-born and lesser or sea-level born in marathon performance.
Here is his response:
1) Diffusing capacity is a measure of the surface area of the lung. It is about ~50 % higher in high altitude natives.
2) More surface area means that it should be “easier” for oxygen to get out of the lungs and into the blood.
3) This is not a big deal at sea level for most healthy people during rest or moderate/heavy exercise. However, in elite athletes the blood travels through the lungs very quickly and can’t always get fully loaded with oxygen. Most of us are about 95-98% loaded at rest and stay that way during exercise. However a lot of elites drop a bit and some into the low 90s. More surface area would reduce the odds of this happening and increase the transport of oxygen to the muscles (and with it the oxygen-carrying red blood cells).
4) Also, if the mechanical work of breathing was less, then the respiratory muscles would need less blood flow and the blood extra flow could go to the legs.
A marathon is ~125 minutes long for the people in your post. The differences in the factors I outline above are tiny and hard to measure, but improvements of a few % (points) in oxygenation would be a big deal as would small reductions in the work of breathing.
Make sense? There are some nuances and other issues here, but this is a pretty good Reader’s Digest explanation….
Thanks to Dr. Joyner for that information. As we all know there are many other factors to take into consideration when evaluating running performance. Having been to Kenya and Ethiopia several times each I can attest to the lifestyle and cultural reinforcements that draw a multitude of young people to distance running in the first place. The economic incentives are also hugely motivating. But even a small difference in oxygen delivery capability can pie-shape-wedge into a critical distinction over time and distance. A 1% difference over a two-hour event is 1.2 minutes, or 72-seconds. The margins may be small, but they may also make all the difference in the world.