Relationship between hand stability and the 10-Hz physiological tremor during various manual tasks.

To quantify an individual's ability to perform manual operations stably, the relationship between hand stability and the 10-Hz physiological tremor was investigated. A total of 35 subjects were assessed when performing force and position control tasks, which were representative of ordinary hand movements. Hand stability was analysed as two components: the fluctuation caused by voluntary control (the control error or inaccuracy when voluntarily maintaining a position or force) and the involuntary oscillatory fluctuation (physiological tremor). The control error was defined by the standard deviation of the low frequency component. The tremor was evaluated based on the power spectrum around 10 Hz. A positive correlation between the control error and the 10-Hz tremor was observed in the finger force control tasks. A correlation between finger tremor and arm tremor also was observed; subjects showing small tremors in the finger tasks also exhibited small tremors when performing the arm tasks. Taken together, the results suggested that the 10-Hz tremor can be used as a benchmark to evaluate an individual's ability to use their hands precisely. STATEMENT OF RELEVANCE: It is important to be able to quantify an individual's ability to perform precise manual operations, such as those required for microsurgery. One important aspect is instability when applying force with a finger. The relationship between hand stability and the 10-Hz physiological tremor was investigated in this study. A correlation was found between control error (or inaccuracy when voluntarily maintaining a position or force) and the 10-Hz tremor in the finger force control tasks and the results suggest that the 10-Hz tremor can be used as a measure to evaluate an individual's ability to use their hands precisely.