Opponens Pollicis Long Latency Reflex during the Ipsilateral Sustained Knee Torque Maintenance

Objective: As a preliminary study to clarify the excitability of central nervous system function during motor control, the aspect of long latency reflex in the upper limbs, which is an indicator of excitability of upper central nervous system function, while maintaining knee extension torque with constant strength.

Methods: Long latency reflex was recorded from opponens pollicis muscle during the ipsilateral sustained torque demonstration of the knee extension by different feedback methods in healthy subjects with maintaining the 25% of individual peak torque by the visual feedback and the verbal instruction. From the acquired waveform, the appearance characteristic of long latency reflex between each task was visually examined.

Results: In 8 out of 10 subjects, the aspect of the long latency reflex was changed according to the difference in task.

Discussion and conclusion: It was suggested that excitability of higher level of cortex might be enhanced if the degree of difficulty becomes higher even if motion control of lower limbs. In the requirement of fine adjustment of motor control, even if the task of lower extremity, it was suggested that the excitability of the cerebral cortex function associated with the upper limb might increase. Because it is not possible to refer to the individual difficulty level of tasks and the skill of lower limbs for each subject in this experiment, follow-up study is needed under the clear conditions of the task, especially individual difficulty and skill.