Bruce Lee's One inch Punch

The Science
Previous studies have shown that the forces generated in a karate punch is not determined by muscular strength but by the brain & nervous system.
In this recent study, researchers looked for differences in brain structure between 12 karate practitioners with a black belt rank and an average of 13.8 years’ karate experience, and 12 control subjects of similar age who exercised regularly but did not have any martial arts experience.
In the first part of the study, the researchers measure the short range (5 cm) punching power of all 24 test subjects by means of infrared markers on their arms & torsos. As expected, the karate masters punched harder than the control subjects.
Analysis of punch biomechanics and brain function revealed the reasons for the difference in punching power.

• The researchers found that punching power depends on timing.
• Specifically, punching force correlated with how well the movement of the wrists and shoulders were synchronized.
• In short, technique + muscular power = Bruce Lee kicking your butt.

• To test brain function, they used diffusion tensor imaging to scan the grey matter (main body of nerve cells) and white matter (bundles of fibres that carry signals from one region of the brain to another) of the test subjects’ brains.

And what they found is that there were major structural differences in the white matter of the cerebellums and primary motor cortex of the karate masters.
It was these differences in the cerebellum that correlated with the synchronicity of the subjects’ wrist and shoulder movements that produced the larger punching forces.

Ref, Cerebral Cortex