Viability of using digital signals from the keyboard to capture typing force exposures.

Although previous studies have shown that systematic temporal changes in keystroke durations may be used as surrogate measures of muscle fatigue, software-based keystroke duration may be adversely affected by different keyswitch force-displacement characteristics. Therefore, this study used a force platform to measure the keystroke durations and compared them to software-based measures in order to determine whether the software-based keystroke duration is a robust surrogate measure for the force-derived durations (independent of keyswitch designs). A total of 13 subjects typed for 15 minutes each on three keyboards with different force-displacement characteristics. The results showed that the software-based keystroke durations closely mirrored and approximated the true force-derived keystroke durations, regardless of the force-displacement characteristics. Furthermore, the subject-dependent correlations indicated that the software-based keystroke durations approximated the true force-derived keystroke durations. Therefore, the software-based keystroke durations could be used as a surrogate non-invasive, cost-effective measure to identify muscle fatigue during computer use for large-scale epidemiological studies. Practitioner Summary: Developing non-invasive, cost-effective computer exposure assessment tools can help researchers develop a better understanding on the underlying mechanisms of computer-related musculoskeletal disorders. This study demonstrates how software measured keystroke duration can be used as a non-invasive, cost-effective exposure assessment measure during computer use.