What is the most famous marital arts move? The Karate Kid‘s “crane kick?” Kill Bill‘s five-point-palm exploding heart technique? I’d argue it’s Bruce Lee’s very real “one-inch punch.” And I think it’s so popular in pop culture because it looks impossible. In demonstrations, Lee seems to produce an amount of force that shouldn’t be possible in that time and distance, and yet he does. But it’s not impossible, or magic, or chi…it’s physics.

In my latest Because Science, I’m breaking down the move that so adeptly breaks boards. The first thing to notice is that all the one-inch punch power does not come from Lee’s arm muscles alone. Instead, Lee is intensely aware of his body’s kinematic chains, or the way the parts of his body link up and interact. When done correctly, the force from the punch doesn’t start at the fist, it starts at his feet.

But kinematic chains, and having the perfect form to take advantage of them, isn’t the full explanation. When you punch something, the force you impart on impact will be related to the kinetic energy your fist generates while moving. And diving into the equation for kinetic energy — and knowing what Lee emphasized in his signature fighting style — you can find exactly out why the one-inch punch is so powerful.

For the full explanation, check out my latest video above!

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Special thanks to Birth of the Dragon for sponsoring today’s episode of Because Science.

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