Is there a difference in cortical representation between dominant and non-dominant arm muscles of elite badminton players?

Training for sport involves the development of skill and coordination. The physiological changes associated with skill acquisition are complex and at present poorly understood. One of the areas in the central nervous system thought to be involved with skill acquisition is the cerebral motor cortex where localised areas are responsible for controlling specific muscle groups. Learning or improving a motor skill may require reorganisation of the cortical areas controlling relevant muscles to accommodate the new skill. To test this idea we studied a group of elite badminton players that were highly skilled in their dominant playing arm. Transcranial magnetic stimulation was used to stimulate the motor cortex, and surface electrodes recorded the evoked muscle response. A forearm wrist flexor muscle was examined in this study and a comparison was made between the representation of this muscle on the motor cortex, with that of the contralateral untrained muscle. The experiments were repeated in a control group of normal subjects to assess if any interhemispheric differences occur under normal conditions. In order to quantify the results, topographic maps were produced illustrating the area of representation of each muscle on the cortex, and the centre of the map. The maps showed the representation taken from the amplitude of the evoked response, and the silent period following this response. Comparison of the maps revealed no significant differences between the trained and untrained muscles, in the size of the representation, or the excitability of the area. The location of the maps was slightly posterior for the athlete group, particularly in the dominant hemisphere, which also showed a non-significant more lateral placement compared to the control group. Skill differences between the dominant and non-dominant arm in badminton players is not reflected in the representation of the muscles on the motor cortex.