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Just How Heavy was Medieval Armor?

Posted by Josh Rothman  July 28, 2011 05:00 AM

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We've all wondered at those huge suits of armor worn by medieval knights and preserved in today's museums: How well could you possibly fight while wearing all that steel? Not very well, according to physiologists Graham N. Askew, Federico Formenti, and Alberto E. Minetti. By asking professional "fight interpreters" to wear armor while walking and running on treadmills, they've been able to show just how much armor constrains movement. Wearing armor, they write, was exhausting, and the huge demands it placed on knights may have led to defeat in many medieval battles.

Their paper, "Limitations imposed by wearing armour on Medieval soldiers' locomotor performance," just published in the Proceedings of the Royal Society B: Biological Sciences, approaches the problem from the point-of-view of energy. By having the interpreters wear oxygen masks while on the treadmill, Askew, Formenti, and Minetti were able to measure how much oxygen they needed to stay in motion. A typical suit of armor could weigh as much as one hundred pounds, but they found that it's not the weight itself that matters -- it's the distribution of that weight. Because each arm and leg is weighed down, it's harder to move, and that makes walking and running more difficult, even as the face mask makes it harder to breathe. Walking with one hundred pounds in a backpack, you'd use 1.7 times as much energy as you would were you not weighed down -- but wearing that weight as armor, you'll use 2.3 times as much.

"The significant energetic cost of moving in armour," the researchers conclude, "is likely to have had a profound limitation on soldiers’ performance, and may have contributed to the outcome of certain battles":

For example, during the Battle of Agincourt (1415), heavily armoured French knights advanced towards the English men-at-arms across terrain made extremely muddy from recent ploughing, over-night rain and an earlier French cavalry charge. Exhaustion of the French knights is cited as a contributing factor to their demise at the hands of the more lightly armoured English archers. Similarly, it has been suggested that exhaustion of the French men-at-arms resulting from several days of marching may have impaired their subsequent performance (in armour) and contributed to their defeat by the English army in the Battle of Crecy (1346).

Not terribly surprising, maybe -- but it's satisfying to see the question settled in such a concrete, empirical way!

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About brainiac Brainiac is the daily blog of the Globe's Sunday Ideas section, covering news and delights from the worlds of art, science, literature, history, design, and more. You can follow us on Twitter @GlobeIdeas.
Brainiac blogger Kevin Hartnett is a writer in Columbia, South Carolina. He can be reached here.

Leon Neyfakh is the staff writer for Ideas. Amanda Katz is the deputy Ideas editor. Stephen Heuser is the Ideas editor.

Guest blogger Simon Waxman is Managing Editor of Boston Review and has written for WBUR, Alternet, McSweeney's, Jacobin, and others.

Guest blogger Elizabeth Manus is a writer living in New York City. She has been a book review editor at the Boston Phoenix, and a columnist for The New York Observer and Metro.

Guest blogger Sarah Laskow is a freelance writer and editor in New York City. She edits Smithsonian's SmartNews blog and has contributed to Salon, Good, The American Prospect, Bloomberg News, and other publications.

Guest blogger Joshua Glenn is a Boston-based writer, publisher, and freelance semiotician. He was the original Brainiac blogger, and is currently editor of the blog HiLobrow, publisher of a series of Radium Age science fiction novels, and co-author/co-editor of several books, including the story collection "Significant Objects" and the kids' field guide to life "Unbored."

Guest blogger Ruth Graham is a freelance journalist in New Hampshire, and a frequent Ideas contributor. She is a former features editor for the New York Sun, and has written for publications including Slate and the Wall Street Journal.

Joshua Rothman is a graduate student and Teaching Fellow in the Harvard English department, and an Instructor in Public Policy at the Harvard Kennedy School of Government. He teaches novels and political writing.


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