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The intriguing science behind Bruce Lee’s one-inch punch

Bruce Lee in 1973. (AP Photo/Columbia Pictures)

It’s a punch that has captivated our imagination for decades. From the distance of one-inch, Bruce Lee could break boards, knock opponents off their feet and look totally badass doing it. It’s one of the most famous — and fabled — blows in the world.

Days ago, Popular Mechanics set out to solve the mystery behind it — and did.

Drawing upon both physical and neuro power, Lee’s devastating one-inch punch involved substantially more than arm strength. It was achieved through the fluid teamwork of every body part. It was his feet. It was hips and arms. It was even his brain. In several milliseconds, a spark of kinetic energy ignited in Lee’s feet and surged through his core to his limbs before its eventual release.

Scientists advise that you watch Lee’s movement closely. If you do, you’ll see every part of his body move. “When watching the one-inch punch, you can see that his leading and trailing legs straighten with a rapid, explosive knee extension,” explained Jessica Rose, a Stanford University biomechanical researcher. The explosion makes Lee twist his hips faster, bringing more power into the shoulder.

Then it drives his elbow forward before the surprising finale. “Flicking his wrist just prior to impact may further increase the fist velocity,” says researcher Rose. According to Popular Mechanics, this “shortens the impact of his blow, which compresses the force and makes it all the more powerful.”

But like a thin baseball player who somehow has home run power — think Ken Griffey Jr. — the true power of the punch doesn’t lie in Lee’s muscles or strength. It’s in coordination. “Muscle fibers do not dictate coordination,” Rose said, “and coordination and timing are essential factors behind movements like this one-inch punch.”

Every bodily jerk has an apex of force. To not only maximize on that force — but to augment it — Lee perfectly synchronizes his movements, one after the other, linking them like boxcars on a train. To be sure, countless muscle men have been stronger than Lee, but few, if any, could deliver more more power than Lee with just one inch.

What makes the difference? Lee’s brain.

In 2012, the journal Cerebral Cortex published an article that gets to the heart of the matter. Why, if a novice martial artist and expert martial artist have approximately the same muscle mass and strength, does the expert consistently have a stronger punch?

“The karate black belts were able to repeatedly coordinate their punching action with a level of coordination that novices can’t produce,” lead researcher Ed Roberts from Imperial College London told the BBC in 2010. “We think that ability might be related to fine tuning of neural connections in the cerebellum.”

An athlete’s coordination is etched into his brain, specifically into the white matter, which facilitates communication between brain cells and orchestrates coordination.

In karate experts, the white matter’s structure was fundamentally altered, which seemed to endow them with improved coordination and more powerful punches. The physical can also train the neural, and that’s exactly what likely happened with Lee.

Every karate chop adds more white matter, improves coordination, generates greater power. And few did more karate chops than Bruce Lee.