Jack T. Dennerlein, Ph.D. Assistant Professor, Environmental Health Harvard School of Public Health, RG-00-0034 Boston, MA Dynamic Tension of the Finger Flexor Muscles The role of the keyboard design in the development of musculoskeletal disorders associated with working with computer workstations is unclear. However, epidemiology studies indicate that one possible risk factor is the exposure of the upper extremity to mechanical forces. Furthermore, there is some evidence that the specific keyboard design, mainly the key switch force-displacement relationship, affects the pain and symptoms of carpal tunnel syndrome. However specific methods and descriptive factors for the loads on these tendons for static, much less a dynamic scenario such as typing, are limited. The specific aim for this proposed three-year study is to build and use a lumped parameter model of the finger, hand and wrist during tapping activities, which will predict the muscle and tendon tension. This tool will be used to assess the affects that differing environmental design has on the muscle/tendon force used to interact with the physical environment of a computer keyboard. First, various parameters will be modified in a simulated model of the finger and the key stroke process in order to determine the effect these parameters have on the fingertip force. After this initial simulation exercise, a set of human experiments, where subjects tap on various keycaps will provide specific force and displacement trajectories for input into the model predicting the muscle/tendon force. These experiments will also explore the effects of various key switch force-displacement characteristics, on both the fingertip and muscle tendon force. Finally, we propose to validate this model by measuring the EMG activity of the muscles during the experiments and, in another experiment, measure the tendon forces in vivo during open carpal tunnel surgery. The proposed work will benefit the clinical community by evaluating and comparing computer-human interface design parameters with the prediction of muscle/tendon force, a possible risk factor for the development of musculoskeletal disorders of the upper extremity associate with computer work. Copyright 2000 The Whitaker Foundation 1700 North Moore Street, Suite 2200, Rosslyn VA 22209 (703) 528-2430     info@whitaker.org