Quantitative evaluation of handwriting: factors that affect pen operating skills.

[Purpose] The purpose of this study was to present control data on writing pressure, the amount of weight on the upper limb, joint angle, and the area of overlap from the sample in graphic tracing tasks, and to extract factors that affect pen-operating skills. [Participants and Methods] The participants included 35 healthy volunteers who performed 1-inch graphic tracing and writing. The measurements were recorded under two conditions as follows: strong and weak writing pressure tasks, and fast and careful writing speed tasks. [Results] In the writing pressure task, increase in pen pressure was accompanied by increase in hand pressure; however, the forearm pressure did not change. In the writing speed task, no significant difference in pressure was observed, except for a slight difference in writing pressure. The degree of variation in pen pressure and areas of overlap were greater in the fast task than in the careful task. Two multiple regression models revealed the contributing factors to pen-operating skills, both showing that the degree of variation in pen pressure was significantly involved. [Conclusion] The multiple regression analysis results showed that pen-operating skills can likely be evaluated, where the degree of variation in writing pressure is an index for deciding the effect of treatment intervention.