In a recent study, Richard Walker and Alice Cooper-Dunn from The Centre for Interdisciplinary Science at the University of Leicester tried to examine the factors for the almost inhuman endurance the men of Rohan and Gondor showed at the Battle of Helms Deep in The Lord of the Rings. In their hypothesis, Walker and Cooper-Dunn suggest: “Assuming that the humans in Middle-earth are physiological analogues of humans on earth […] an increased oxygen concentration allows for greater endurance”.
For their study, Walker and Cooper-Dunn examined the oxygen levels of our earth with that of Middle-earth. In addition, they used Aragorn as a test subject. According to their study, the oxygen content of Middle-earth is assumed to be almost 10% higher than that of our Earth:
“This value indicates that Aragorn’s superior endurance, taken as an example of a man fighting at Helms Deep, might be caused by a higher oxygen content in Middle-earth.”
Moreover, Walker and Cooper-Dunn also conclude that these higher oxygen levels explain the occurrence of dragons and giant spiders such as Shelob.
This interdisciplinary approach is, indeed, a highly fascinating read. Yet, a few questions remain. For one, it remains unclear throughout the study whether Tolkien’s original or Peter Jackson’s movie trilogy have been used. Also, in my opinion, their choice to use Aragorn as a test subject might not have been the best decision. While Walker and Cooper-Dunn acknowledge that Aragorn is a Dunedain and, therefore, not a human like you and me, they still compare Aragorn to regular humans. Despite Aragorn’s physical prowess of a man in his mid-thirties, as Walker and Cooper-Dunn approximate, Aragorn is not like a regular man. For the study, King Theoden or some of his warriors would’ve been better test subjects. Likewise, the origins of creatures such as Shelob or dragons lie in the magic and other-worldly past of Middle-earth rather than in the oxygen levels.
Having said that, of course one cannot expect a comprehensive explanation for such a vast and complex issue. Walker and Cooper-Dunn themselves explained that even factors such as mean lung capacity vor elevated levels of adrenaline can also affect physical performance.
You can read the full study over here.