John Lloyd, PhD CPE - Ergonomic Analysis of Pen Comfort and Wrist Dynamics While Writing

John D. Lloyd, PhD, CPE
Board Certified Ergonomist

32824 Michigan Avenue
San Antonio, Florida 33576

Tel: 813-624-8986

Ergonomic Analysis of Pen Comfort and Wrist Dynamics While Writing

Abstract: An ergonomic evaluation of pen use was performed at the Center for Product Ergonomics. The primary objective of this study was to determine whether differences in pen type influenced writing characteristics and user preferences. Our secondary goal was to evaluate the relationship between hand anthropometry and wrist dynamics while writing. Thirteen (13) subjects participated in this study and were evaluated while performing a standardized writing task. During these tasks, thenar muscle activity (EMG) and three-dimensional wrist motion were monitored. In addition, participants were asked to complete questionnaires rating pen features and pen preferences for each of the five, randomly ordered, writing instruments assessed. Subject hand anthropometry and upper extremity musculoskeletal health status were also recorded. The pens utilized in this study were ErgoPen (A), Mont Blanc ball-point (B), Bic Round Stic (C), Papermate Flexgrip fine (D) and Pilot V Ball extra fine (E)

Figure 1 : Pen designs evaluated

Smaller handed participants reported greater levels of comfort while writing. Statistical trends suggest that overall preference for Pen A may be due to surface geometry and texture (grip preference). Assessment by pen type indicated no significant differences in path length, writing speed or wrist motion while writing. Results indicate that larger-handed participants produced a greater path length, wrote faster even though self paced and produced less thenar EMG activity, represented as a percentage of maximum voluntary pinch capacity. Dynamic range of motion for the wrists (flexion/extension and pronation/supination) did not differ significantly as a function of hand size, however ulnar/radial range of motion was significantly greater for larger handed participants. Analysis of pen preference by hand size indicates that smaller handed participants preferred Pen E, the smallest pen, conversely larger handed participants preferred the largest pen, Pen A.

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