K. Farris, R. Fehrenbacher, E. Hayes, R. McEvoy, A. Smith, R. McCulloch

Gonzaga University, Spokane, WA

PURPOSE:This study aimed to evaluate differences in handwriting characteristics when using the four primary handwriting grip styles: dynamic quadrupod (DQ), dynamic tripod (DT), lateral quadrupod (LQ) and lateral tripod (LT). It was hypothesized that different writing styles would alter muscle recruitment, writing legibility, and consistency. METHODS: Thirty-four 18-22-year-old subjects underwent three protocols involving tests of handwriting legibility, consistency, and metrics. The legibility test was conducted on paper. The consistency and metrics protocols included surface electromyography (EMG) to measure the activity of 6 muscles involved in handwriting and were performed on a digital writing tablet. The tablet was used to measure stroke duration, length, velocity, and pen pressure. Subjects used each grip style with all protocols, and scores were normalized to their native grip scores. Grip styles were compared using RM ANOVA, t-tests, and correlations to evaluate relationships (p<.05 was significant, p<.10 was considered a trend). RESULTS: Females had a lower range in legibility scores than males by 3.483% ± 1.676% (p=.046), but grip style did not impact legibility. The upper trapezius (UT) was more active in the lateral grips compared to DT by 15.9%± 5.2% and by 14.6% ± 3.7%, respectively (p=.028, p=.004, respectively). DT had more extensor carpi ulnaris activity than LT by 9.7%± 3.3%,(p=.011).CONCLUSION: Females are likely to be able to use any grip style with little effect on legibility, but males’ legibility scores may drop more. This implies that in rehabilitation, females may be able to adapt to any grip style, but males may benefit from using dynamic grip styles rather than laterals. As suggested by elevated UT activity, lateral grip styles involve more whole-arm, stabilizing movements, suggesting that in rehabilitation, a patient with little gross muscle activation, such as the UT, may benefit from a dynamic grip style to regain handwriting ability or use lateral grip styles to build muscle tone. Increased ECU activity implied that dynamic grip styles require fine dexterous movements. In rehabilitation, patients with poor dexterity may be advised to avoid DT or use it to improve precision. The characterization of the primary grip styles provides useful information for patient rehabilitation.

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