Objectives This study concerned the influence of 6 positions of the computer mouse on the work table on posture, muscular load, and perceived exertion during text editing. Methods An optoelectronic 3-dimensional motion analysis system was used to register the postures of 10 men and 10 women using video display units. Muscular load was also registered (with electromyography), as was perceived exertion (with rating scales). Results A neutral posture with a relaxed and supported arm showed the least perceived exertion, and the electromyographic results showed low activity in both trapezius muscles in this position. Short operators (all women) showed a numerically higher activity in the 4 examined muscles than the tall operators (all men, except 1). This finding could be related to lower muscle force among women and to anthropometric differences, which also influence biomechanic load moments. Narrow-shouldered operators (8 women and 1 man) and short operators worked with larger outward rotation and abduction of the shoulder in a position of the mouse lateral to the keyboard than the broad-shouldered (7 men and 2 women) and tall operators did. Alm support markedly reduced muscle load in the neck-shoulder region among the operators. C O~~C~U S~O~~S The operators using video display units in this study prefell-ed to use the mouse on a table in a close to relaxed, neutral posture of the arm in combination with arm support. Short and narrow-shouldered operators worked in more strenuous postures of the arm when the mouse was located lateral to the keyboard.Key terms arm support, electromyography, input device, MacReflex motion analysis system, subjective ratings, upper limb, video display unit.In recent years, the occurrence of cumulative trauma disorders such as carpal tunnel syndrome and tendinitis has increased dramatically in the United States, and these diseases account for over 60% of occupational illnesses (1). Video display terminal users have reported musculoskeletal symptoms primarily in the upper limbs, neck, and shoulders (2, 3). Health problems during work with video display terminals have been reported also in Sweden (4,5).The computer mouse and other nonkeyboard input devices supplement the keyboard in many visual display unit (VDU) workstations. The mouse technique changes posture and movements compared with keyboard use without the mouse (6). Franzblau et a1 (7) found the incidence of cavpal tunnel syndrome to be related to the pattern of mouse usage in a medical illustration department.Associations between self-reported neck and upper-limb symptoms and physical exposure factors at VDU workstations have recently been investigated (8). The study showed that long hours of work with the mouse, as well as work with the mouse nonoptimally located on the table, seem to be risk factors for upper-limb symptoms.Several significant relationships between the design of workstations or postures on one hand and the incidence of complaints or medical findings on the other have been discovered among VDU operators using a...

We conducted a case-referent study to identify and quantify work-related and non-work-related risk indicators for reported over-exertion back injuries among nursing personnel. The source population was all nursing personnel employed in the Stockholm County hospitals during a 32-month period. The 240 cases and 614 referents completed questionnaires about occupation, type of clinic, working hours, shift work, patient transfers, perceived exertion, back pain, prior back injury, job strain, body mass index (BMI), smoking, immigrant status, physical training, and self-rated fitness. The highest relative risks (RR) were observed for work-related factors: working at an orthopedic clinic (RR = 5.2; 95% CI = 2.7-10.2), > or =1 patient transfer/shift (RR = 2.7; 95% CI = 1.6-4.5), and working full-time (RR = 2.4; 95% CI = 1.6-3.6). Training in the use of transfer devices, and regular use of transfer devices, reduced the relative risk from patient transfer. Among the non-work-related factors, only body mass index > or =25 kg/m2 and immigrant status was associated with a slight increase in relative risk.

Experiments were designed to determine how cold-induced vasoconstriction is mediated in superficial vessels of human finger skin. alpha-Adrenoceptor antagonists were administered into the finger skin by iontophoresis, and local cooling was applied by a laser-Doppler probe supplied with Peltier elements. Cold-induced vasoconstriction was abolished after administration of the alpha 2-adrenoceptor antagonist rauwolscine but not after the alpha 1-adrenoceptor antagonist doxazosin. The results indicate that vasoconstriction on local cooling in human finger skin is mainly mediated by adrenoceptors of the alpha 2-subtype.

Symptoms of the neck and upper extremities in dentists. Scand J Work En viron Health 1990;16:129-34. Symptoms of the neck, shoulders. arms, and hands of 99 dentists and a reference group of 100pharmacists were studied by means of a telephone interview. Forty-four percent of the dentists and 26 % of the pharmacists reported symptoms of the neck [relative risk (RR) 2.1, 95 070 confidence interval (95 % CI) 1.4-3.1]. Symptomsof the shoulder were reported by 51 % of the dentists and 23 % of the pharmacists (RR 2.2. 95 % CI 1.5-3.3). Musculoskeletal symptoms in the forearm were present almost exclusively in the dentists (1 2 versus I %) . Numbness and paresthesia were more common among the dentists than among the referents (RR 4.2, 95 % CI 2.3-7.7). Unilateral Raynaud's phenomenon in the dominant hand occurred in six dentists and one pharmacist. The high frequency of symptoms from the neck, shoulders, and upper extremities of the dentists was probably related to their difficult work positions with cervical flexion and rotation, abducted arms, and repetitive precision-demanding handgrips.

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