Any fan of martial arts movie legend Bruce Lee will remember his famous one-inch punch, with which he was able to strike an opponent from extremely close range and send them flying.
Brain scans have revealed that fine-tuned differences between the neural structure of expert martial artists and fighting novices could be the reason that the one-inch punch is possible.
Black belts are able to punch incredibly hard from close range but studies have found that the force generated is not determined by raw muscular strength, suggesting factors related to the control of muscle movement by the brain might be important.
Researchers from Imperial College London and UCL 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 people of similar age who exercised regularly but did not have any martial arts experience.
The researchers tested how powerfully the subjects could punch, but to make useful comparisons with the punching of novices they restricted the task to punching from short range – a distance of 5 centimeters (roughly 1 inch).
As expected, the karate group punched harder, but the power of their punches seemed to be down to timing, rather than their strength: the force they generated correlated with how well the movement of their wrists and shoulders were synchronized.
Dr Ed Roberts, from the Department of Medicine at Imperial College London, who led the study, explained: ‘The karate black belts were able to repeatedly coordinate their punching action with a level of coordination that novices can’t produce.
“We think that ability might be related to fine-tuning of neural connections in the cerebellum, allowing them to synchronize their arm and trunk movements very accurately.”
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 fibers that carry signals from one region to another.
Diffusion tensor imaging (DTI) scans found 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.
“We’re only just beginning to understand the relationship between brain structure and behaviour, but our findings are consistent with earlier research showing that the cerebellum plays a critical role in our ability to produce complex, coordinated movements,” added Dr Roberts.
“There are several factors that can affect the DTI signal, so we can’t say exactly what features of the white matter these differences correspond to. Further studies using more advanced techniques will give us a clearer picture.”
The findings are published today in the journal Cerebral Cortex.
Bruce Lee’s One-Inch Punch
Attribution: Daily Mail