Looking at a suit of armor, it’s easy to imagine that walking around in the thing, much less swinging a broadsword, is difficult. There are legends that some suits of armor were so heavy that if a knight fell face down in a puddle he would drown. Movies and books often show knights in armor being hoisted onto their horses by a special crane for jousting tournaments, though there is little to no evidence for the practice.

Rather, while suits of armor did add extra weight, research by medievalist Daniel Jaquet at the Max Planck Institute for the History of Science shows that some knights were downright spry in their armor.

For a paper in the journal Historical Methods, Jaquet dressed a volunteer in replica armor made from the same materials and in the same manner as medieval armor. The team then recorded the subject walking and running on a treadmill, analyzing his gait and range of motion using 3-D kinematics. What they found is that while the armor did add weight and increased energy use, the wearer retained most of his range of motion.

To show off just how wearable the suit of armor could be, the researchers created their own video. In a post on Medievalists.net, Jacquet writes that they put their research subject through the workout of early 15th French knight Jean le Maingre, known as Boucicaut. An accomplished battlefield combatant, he was also known as the most physically fit knight of his age. That’s because he followed a strict workout regimen, which is included in an account of his deeds.

To test the suit of armor, Jacquet’s subject followed Boucicaut’s routine, running and walking along trails and through the city in the armor and jumping onto a pommel horse to simulate jumping on a horse. He also chopped a pile of wood with an axe and climbed the underside of a ladder monkey bar-style. In an attempt to recreate Boucicaut’s scaling of towers in his armor, the modern knight climbed at an indoor rock-climbing gym. He also performs somersaults and cartwheels and danced a little.

The armor does not seem to hinder his movement. “The relatively impressive added load is comparable to the one imposed on modern soldiers with bullet proof vest and full gear, or to the one imposed on the fireman with his oxygen bottles,” writes Jacquet. “Therefore, the trained body of the wearer adapts to such a heavy load and is able to achieve top physical performances, but limited by the added load.”

A study conducted at Leeds University several years ago showed that subjects on a treadmill dressed in armor similar to what would have been worn by 15th century London Sheriff William Martyn did need to exert more energy, as Jennifer Oullette at Gizmodo reports. Indeed, they used 1.9 times as much energy while running and 2.3 times as much while walking, according to the study. The findings, not surprising, do illustrate just how physically fit knights needed to be to perform well in armor.

Jacquet writes that he hopes to repeat the study using different varieties of armor and also investigate some of the layers beneath the armor that could limit range of motion.