We found that using a mouse in the DP rather than the PP leads to less activity of the external rotators, less perceived fatigue and more productivity. This suggests that the DP is preferable to the PP for computer work involving a mouse.

Objectives: This study investigated the association between task-induced stress and fatigue by examining the cardiovascular responses of subjects using different mouse positions while operating a computer under time constraints. Material and Methods: The study was participated by 16 young, healthy men and examined the use of optical mouse devices affixed to laptop computers. Two mouse positions were investigated: (1) the distal position (DP), in which the subjects place their forearms on the desk accompanied by the abduction and flexion of their shoulder joints, and (2) the proximal position (PP), in which the subjects place only their wrists on the desk without using an armrest. The subjects continued each task for 16 min. We assessed differences in several characteristics according to mouse position, including expired gas values, autonomic nerve activities (based on cardiorespiratory responses), operating efficiencies (based on word counts), and fatigue levels (based on the visual analog scale -VAS). Results: Oxygen consumption (VO 2 ), the ratio of inspiration time to respiration time (T i /T total ), respiratory rate (RR), minute ventilation (VE), and the ratio of expiration to inspiration (Te/T i ) were significantly lower when the participants were performing the task in the DP than those obtained in the PP. Tidal volume (VT), carbon dioxide output rates (VCO 2 /VE), and oxygen extraction fractions (VO 2 /VE) were significantly higher for the DP than they were for the PP. No significant difference in VAS was observed between the positions; however, as the task progressed, autonomic nerve activities were lower and operating efficiencies were significantly higher for the DP than they were for the PP. Conclusions: Our results suggest that the DP has fewer effects on cardiorespiratory functions, causes lower levels of sympathetic nerve activity and mental stress, and produces a higher total workload than the PP. This suggests that the DP is preferable to the PP when operating a computer. Corresponding author: S. Sako, Department of Physical Therapy, Nagoya Isen School Corporation Vocational College, Nagoya Isen, 4-27-1, Meieki, Nakamura, Nagoya, Aichi 450-0002, Japan (e-mail: sako.shunji@isen.ac.jp). Nofer Institute of Occupational Medicine, Łódź, Poland O R I G I N A L P A P E R S. SAKO ET AL. IJOMEH 2014;27(4)548 the use of a mouse, which are generally considered light work [20]. (Computer arm syndrome is a musculoskeletal disorder that typically manifests as pain in the upper extremities and the posterior region of the neck). The side of the upper extremity used to operate the mouse [8,[21][22][23][24], differences in mouse positions [25,26], differences in the shape of the mouse [20,[27][28][29], the speed of mouse use in detailed operations [30], and differences caused by the use of armrests [29] can all contribute to CRDs that arise from the use of a mouse. However, these previous investigations of mouse-based activities have primarily focused on the association between operating a computer and m...

Transverse osseous structure of the carpal groove was studied using serial sections and microradiography. The width and area of the carpal groove were measured in x-ray films of each section. The wrist and carpal region was divided into six levels: 1) radio-ulnar joint level, 2) proximal level of the carpal bones, 3) intermediate level of carpal bones, 4) distal level of carpal bones, 5) the first C-M joint level, and 6) bases of the metacarpal bone level. The width of the carpal groove averaged 32 mm at the inlet and became narrower toward the outlet. Both inlet and outlet areas were small, the largest area was observed at the middle part. Although the carpal bones did not support the body weight, a remnant of the trajectorial architecture of the trabeculae was observed.

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