says Jearl Walker, Cleveland State professor and author of the classic book Flying Circus Physics. And when he got the professor gig, he decided to investigate why. First, he filmed himself throwing forward punches and then measured the distance his hand traveled each frame to discover where the punch reached maximum velocity. Sure enough, a punching hand is fastest at 80 percent of arm extension. After that, it’s already slowing down to retract. Imagining a punch detonating behind the target’s surface helps to ensure maximum speed on impact.But max speed is only one of three factors that make the perfect punch. Imagine the superfast flick of your finger—it’s annoying behind the ear, but it’s unlikely to cause real damage. “What you want is maximum pressure,” says Walker. This is high momentum applied over a small surface area, and it’s why many martial arts teach striking with the side of the hand or the four pointy knuckles of your bent fingers—decreased surface area is like whacking a person with a stiletto heel instead of the sole of a sneaker.
