The peculiar walk of one Vladimir Putin (left arm swinging naturally, right arm stiff at his side) has been the subject of speculation, with guesses ranging from childhood illness to an in-utero stroke, Live Science reports. But a group of Dutch neuroscientists—or "movement disorder enthusiasts," as they call themselves—has a different theory in a study published in the British Medical Journal: "gunslinger's gait" brought about by his KGB training. When study co-author Bastiaan Bloem first started watching Putin perambulating in YouTube videos, he thought he suffered from Parkinson's disease, since a reduced arm swing is a symptom—but he ruled that out, since Parkinson's is progressive and Putin never got worse. (The scientists compared Putin's health with that of Adolf Hitler, who some neurologists believe did suffer from Parkinson's and who exhibited a range of symptoms.) Then something odd happened: Bloem and his team noticed four other high-ranking Russian officials, including PM Dmitry Medvedev, had the exact same walk.
After some searching—and coming to the conclusion that all five Russians couldn't have Parkinson's disease that affected them all in the exact same way—they stumbled across their answer in the most unlikely of places: a KGB weapons training manual. "It literally says, when you're walking, don't move the right arm, keep it close to the holster and be ready to draw the gun," Bloem tells Live Science. The scientists also studied Hollywood Westerns and confirmed that the right arms of old-time cowboys stayed similarly immobile, Live Science notes. Only one of the other officials besides Putin was actually in the KGB, but two of the other men may have received similar training for their military roles. As for Medvedev, who was in neither the KGB nor the military, the team suggests he's simply engaging in a practice not uncommon in Russia: "imitating the boss" and picking up on his mannerisms. (Not only does Putin walk like an American cowboy, he admires our creativity, too.)