The relationship between muscle activation and handwriting quality with non-native grip styles

Purpose This study aimed to explore the differences in muscle activity, handwriting legibility, and consistency when using the 4 primary handwriting grip styles: dynamic quadrupod (DQ), dynamic tripod, lateral quadrupod (LQ) and lateral tripod. Study Design and Methods Thirty-four 18-22-year-old participants completed a handwriting legibility test on paper as well as consistency and metrics tests using both surface electromyography and a digital writing tablet. Electromyography was used to measure the activity of 6 muscles associated with handwriting, and the tablet measured stroke duration, length, velocity, and pen pressure. Subjects used each grip style with all protocols and scores were normalized to their native grip. Significance was set at P Results Females had a lower range in legibility scores than males by 3.5% ± 1.7% (p = .046, d = 0.713), but grip style did not impact legibility. The upper trapezius (UT) was more active in the lateral tripod and LQ grips compared to DQ by 16.8% ± 5.2% and by 13.8% ± 5.2%, (p = .007, p = .012, respectively, partial η2 = 0.188). The stroke duration was greater in the LQ grip style than dynamic tripod and DQ grip styles (p = .008, p = .023, respectively; partial η2 = 0.123). Conclusions Lateral grip styles involve more whole-arm, stabilizing movements while dynamic grip styles require fine dexterous movements. Furthermore, females are likely to be able to employ any grip with minimal effect on legibility. For a patient needing guidance in rehabilitation, understanding the differences in grips could aid selection of the optimum grip style to employ based on their muscular control deficits.