Hi-yah! Karate experts are able to generate extremely powerful punches - much more powerful than what could've been generated by muscle strength alone - so what's their secret?
Turns out, it's all in the brain:
The study, published in the journal Cerebral Cortex, 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. [...]
Brain scans showed that the microscopic structure in certain regions of the brain differed between the two groups. Each brain region is composed of grey matter, consisting of the main bodies of nerve cells, and white matter, which is mainly made up of bundles of fibres that carry signals from one region to another. The scans used in this study, called diffusion tensor imaging (DTI), detected structural differences in the white matter of parts of the brain called the cerebellum and the primary motor cortex, which are known to be involved in controlling movement.
The differences measured by DTI in the cerebellum correlated with the synchronicity of the subjects’ wrist and shoulder movements when punching. The DTI signal also correlated with the age at which karate experts began training and their total experience of the discipline. These findings suggest that the structural differences in the brain are related to the black belts’ punching ability.