title: A prospective study of computer users: I. Study design and incidence of musculoskeletal symptoms and disorders. A Cross-Country Comparison of Short-and Long-Term Effects of an Ergonomic Intervention on Musculoskeletal Discomfort, Eyestrain and Psychosocial Stress in VDT Operators: Selected Aspects of the International Project The Effect of an Ergonomic Intervention on Musculoskeletal, Psychosocial and Visual Strain of VDT Data Entry Work: The Polish Part of the International Study A randomised controlled trial evaluating the effects of two workstation interventions on upper body pain and incident musculoskeletal disorders among computer operators Influence of time pressure and verbal provocation on physiological and psychological reactions during work with a computer mouse The Southampton examination schedule for the diagnosis of musculoskeletal disorders of the upper limb The Effect of an Ergonomie Intervention on Musculoskeletal, Psychosocial and Visual Strain of VDT Data Entry Work: The Norwegian Part of the International Study The Effect of an Ergonomic Intervention on Musculoskeletal, Psychosocial and Visual Strain of VDT Entry Work: Organization and Methodology of the International Study Musculoskeletal, visual and psychosocial stress in VDU operators before and after multidisciplinary ergonomic interventions. A 6 years prospective study--Part II. A prospective study of computer users: II. Postural risk factors for musculoskeletal symptoms and disorders. Computer users' risk factors for developing shoulder, elbow and back symptoms. The Effect of an Ergonomic Intervention on Musculoskeletal, Psychosocial and Visual Strain of VDT Data Entry Work: The United States Part of the International Study Computer mouse position as a determinant of posture, muscular load and perceived exertion. Risk factors in the onset of neck/shoulder pain in a prospective study of workers in industrial and service companies A randomised controlled trial evaluating an alternative mouse and forearm support on upper body discomfort and musculoskeletal disorders among engineers Job task and psychosocial risk factors for work-related musculoskeletal disorders among newspaper employees.
abstract: BACKGROUND A prospect i ve study of computer users was performed to determine the occurrence of and evaluate risk factors for  neck or shoulder ( N/S ) and h and or arm ( H/A ) musculoskeletal symptoms ( MSS ) and disorders ( MSD ) . METHODS Individuals ( n = 632 ) newly hired into jobs requiring > or = 15 hr/week of computer use were followed for up to 3 years . At study entry , workstation dimensions and worker postures were measured and medical and psychosocial risk factors were assessed . Daily diaries were used to document work practice s and incident MSS . Those reporting MSS were examined for specific MSD . Incidence rates of MSS and MSD were estimated with survival analysis . Cox regression models were used to evaluate associations between participant characteristics at entry and MSS and MSD . RESULTS The annual incidence of N/S MSS was 58 cases/100 person-years and of N/S MSD was 35 cases/100 person-years . The most common N/S MSD was somatic pain syndrome . The annual incidence of H/A MSS was 39 cases/100 person-years and of H/A MSD was 21 cases/100 person-years . The most common H/A disorder was deQuervain 's tendonitis . Forty-six percent of N/S and 32 % of H/A MSS occurred during the first month of follow-up . Gender , age , ethnicity , and prior history of N/S pain were associated with N/S MSS and MSD . Gender , prior history of H/A pain , prior computer use , and children at home were associated with either H/A MSS or MSD . CONCLUSIONS H/A and N/S MSS and MSD were common among computer users . More than 50 % of computer users reported MSS during the first year after starting a new job Three groups of data entry female visual display terminal ( VDT ) workers from Norway ( n = 30 ) , Pol and ( n = 33 ) and the USA ( n = 29 ) were compared . Before intervention , the Norwegian group reported more neck pain compared with the Polish group . The Polish group reported less shoulder pain than both the U.S. and the Norwegian groups . The clinical examination documented fewer symptoms and signs of musculoskeletal illness among the Polish participants compared with the Norwegian and the U.S. groups . After intervention , the Norwegian group reported a reduction in neck pain while the U.S. group reported a reduction in shoulder pain . The Polish group reported an increase in neck , shoulder and forearm pain at follow-up compared to after intervention . The Polish group recorded higher flexion of the upper arm at follow-up parallel with an increase of pain in the upper part of the body . Visual discomfort showed variable results in the 3 countries A group of routine data entry operators ( female ) was included in the Polish MEPS ( musculoskeletal — eyestrain— psychosocial — stress ) study . Before the intervention , ergonomic assessment revealed improper working conditions such as inadequate lighting , uncomfortable chairs , and lack of forearm and wrist support while medical examination revealed that trapezius muscle load along with upper arm , head and back angles were higher than advisable . Subjects complained about neck and shoulder pain , visual problems , and psychosocial conditions . The ergonomic intervention included installation of new luminaires and Venetian blinds , new chairs , repair of ventilators , and optometric corrections . The results after the intervention showed mainly improvement in chair comfort , lighting conditions , visual strain , and sitting posture . However , financial limitations did not allow satisfactory completion of the intervention leading to a mixed interpretation of the results Background : Call centre work with computers is associated with increased rates of upper body pain and musculoskeletal disorders . Methods : This one year , r and omised controlled intervention trial evaluated the effects of a wide forearm support surface and a trackball on upper body pain severity and incident musculoskeletal disorders among 182 call centre operators at a large healthcare company . Participants were r and omised to receive ( 1  ) ergonomics training only , ( 2 ) training plus a trackball , ( 3 ) training plus a forearm support , or ( 4 ) training plus a trackball and forearm support . Outcome measures were weekly pain severity scores and diagnosis of incident musculoskeletal disorder in the upper extremities or the neck/shoulder region based on physical examination performed by a physician blinded to intervention . Analyses using Cox proportional hazard models and linear regression models adjusted for demographic factors , baseline pain levels , and psychosocial job factors . Results : Post-intervention , 63 participants were diagnosed with one or more incident musculoskeletal disorders  . Hazard rate ratios showed a protective effect of the armboard for neck/shoulder disorders ( HR = 0.49 , 95 % CI 0.24 to 0.97 ) after adjusting for baseline pain levels and demographic and psychosocial factors . The armboard also significantly reduced neck/shoulder pain ( p = 0.01 ) and right upper extremity pain ( p = 0.002 ) in comparison to the control group . A return-on-investment model predicted a full return of armboard and installation costs within 10.6 months . Conclusion : Providing a large forearm support combined with ergonomic training is an effective intervention to prevent upper body musculoskeletal disorders and reduce upper body pain associated with computer work among call centre employees Abstract . The overall aim of this study was to investigate whether time pressure and verbal provocation has any effect on physiological and psychological reactions during work with a  computer mouse . It was hypothesised that physiological reactions other than muscle activity ( i.e. wrist movements , forces applied to the computer mouse ) would not be affected when working under stressful conditions . Fifteen subjects ( 8 men and 7 women ) participated , performing a st and ardised text-editing task under stress and control conditions .  Blood pressure , heart rate , heart rate variability , electromyography , a force-sensing computer mouse and electrogoniometry  were used to assess the physiological reactions of the subjects . Mood ratings and ratings of perceived exertion were used to assess their psychological reactions . The  time pressure and verbal provocation  ( stress situation ) result ed in increased physiological and psychological reactions compared with the two control situations . Heart rate , blood pressure and muscle activity in the first dorsal interosseus , right extensor digitorum and right trapezius muscles were greater in the stress situation . The peak forces applied to the button of the computer mouse and wrist movements were also affected by condition . Whether the increases in the physiological reactions were due to stress or increased speed/productivity during the stress situation is discussed . In conclusion , work with a computer mouse under time pressure and verbal provocation ( stress conditions ) led to increased physiological and psychological reactions compared to control conditions OBJECTIVES Following a consensus statement from a multidisciplinary UK workshop , a structured examination schedule was developed for the diagnosis and classification of musculoskeletal disorders of the upper limb . The aim of this study was to test the repeatability and the validity of the newly developed schedule in a hospital setting . METHOD 43 consecutive referrals to a soft tissue rheumatism clinic ( group 1 ) and 45 subjects with one of a list of specific upper limb disorders ( including shoulder capsulitis , rotator cuff tendinitis , lateral epicondylitis and tenosynovitis ) ( group 2 ) , were recruited from hospital rheumatology and orthopaedic outpatient clinics . All 88 subjects were examined by a research nurse ( blinded to diagnosis ) , and everyone from group 1 was independently examined by a rheumatologist . Between observer agreement was assessed among subjects from group 1 by calculating Cohen 's κ for dichotomous physical signs , and mean differences with limits of agreement for measured ranges of joint movement . To assess the validity of the examination , a pre-defined algorithm was applied to the nurse 's examination findings in patients from both groups , and the sensitivity and specificity of the derived diagnoses were determined in comparison with the clinic 's independent diagnosis as the reference st and ard . RESULTS The between observer repeatability of physical signs varied from good to excellent , with κ coefficients of 0.66 to 1.00 for most categorical observations , and mean absolute differences of 1.4 ° –11.9 ° for measurements of shoulder movement . The sensitivity of the schedule in comparison with the reference st and ard varied between diagnoses from 58%–100 % , while the specificities ranged from 84%–100 % . The nurse and the clinic physician generally agreed in their diagnoses , but in the presence of shoulder capsulitis the nurse usually also diagnosed shoulder tendinitis , whereas the clinic physician did not . CONCLUSION The new examination protocol is repeatable and gives acceptable diagnostic accuracy in a hospital setting . Examination can feasibly be delegated to a trained nurse , and the protocol has the benefit of face and construct validity as well as consensus backing . Its performance in the community , where disease is less clear cut , merits separate evaluation , and further refinement is needed to discriminate between discrete pathologies at the shoulder The Norwegian MEPS ( musculoskeletal — eyestrain — psychosocial — stress ) study included 3 groups : data entry , data dialogue ( female ) and data dialogue  ( male ) . Before intervention , the data entry group reported significantly more symptoms and signs of musculoskeletal illness and had longer periods in front of the video display terminal ( VDT ) without a break . The ergonomic intervention consisted mainly of ergonomic information and training . After intervention , the data dialogue female group reported a significant reduction in shoulder pain in parallel with a reduction in trapezius load . Increasing the underst and ing in how to adjust the work st and and chair may have been contributing factors to reducing the pain level . There was a significant reduction in eye problems in all groups ; the greatest reduction in eye symptoms was seen in the groups who had new optometric corrections This special issue of the International Journal of Occupational Safety and Ergonomics ( JOSE ) reports the results from an extensive multinational and multidisciplinary collaborative investigation of the impacts on  visual display terminal ( VDT ) work  of musculoskeletal , visual , ergonomic , and psychosocial factors . For brevity , this effort has been referred to as the MEPS project ( musculoskeletal — eyestrain — psychosocial — stress ) . This paper lays out the basic method ological structure of the study . The study was conducted in 4 countries utilizing VDT data entry workers as the primary subject population . A battery of objective and subject assessment measures , including muscle load , visual function , physical and visual strain , postural , ergonomic and psychosocial factors , were assessed at 3 different points in time . A pre-test was given prior to an ergonomic intervention . Two post-tests were given 1 month and 1 year after the ergonomic intervention A prospect i ve epidemiological field study covering a 2 years period has earlier been published . The study has a parallel group design with two intervention groups ( T and S ) and one  control group ( C ) of Visual Display Unit ( VDU ) operators . The present paper covers the period from 2 to 6 years of the study . After 3.5 years , the C group got the same intervention in terms of new lighting system , new workplaces and at last an optometric examination and corrections if needed . The C group reported a significant reduction in visual discomfort after interventions while the two groups ( T and S ) continued to report significant reduction of visual discomfort after 6 years . By supporting the forearm on the table top , the C group reported significant reduction of shoulder and neck pain while the T group reported significant reduction in shoulder and back pain after 6 years . Organizational and psychosocial factors at work and outside work did not show any significant changes during the study period BACKGROUND Despite widespread recommendations regarding posture during computer use , associations between specific postures and musculoskeletal health are not well characterized . METHODS Six hundred and thirty-two newly hired computer users were followed prospect ively to evaluate associations between posture and neck or shoulder ( N/S ) and h and or arm ( H/A ) musculoskeletal symptoms and musculoskeletal disorders . Participants ' postures were measured at entry and they reported symptoms on weekly diaries . Participants reporting symptoms were examined for specific disorders . Multivariate Cox regression models were used to estimate associations between postural variables and risk of symptoms and disorders , controlling for confounding variables . RESULTS Keying with an inner elbow angle > 121 degrees , greater downward head tilt , and presence of armrests on the participants chair were associated with lower risk of N/S symptoms or N/S disorders .  Keying with elbow height below the height of the " J " key and the presence of a telephone shoulder rest were associated with a greater risk of N/S symptoms or N/S disorders . Horizontal location of the " J " key > 12 cm from the edge of the desk was associated with a lower risk of H/A symptoms and H/A disorders . Use of a keyboard with the " J " key > 3.5 cm above the table surface , key activation force > 48 g , and radial wrist deviation of > 5 degrees while using a mouse was associated with a greater risk of H/A symptoms or H/A disorders . The number of hours keying/week was associated with H/A symptoms and disorders . CONCLUSIONS The results suggest that the risk of musculoskeletal symptoms and musculoskeletal disorders may be reduced by encouraging specific seated postures OBJECTIVES This prospect i ve study concentrated on determining factors of computer work that predict  musculoskeletal symptoms in the shoulder , elbow , and low-back regions . METHODS A question naire on ergonomics , work pauses , work techniques , and psychosocial and work factors was delivered to 5033 office workers at baseline in early 1999 ( response rate 69 % ) and to 3361 respondents at the time of the follow-up in late 2000 ( response rate 77 % ) . An increased frequency or intensity of symptoms was the outcome variable , including only nonsymptomatic respondents from the baseline question naire ( symptom frequency below 8 days within the last 12 months or intensity score below 4 within the last 3 months ) . RESULTS In the follow-up , 10 % , 18 % , and 23 % had symptoms more often in the elbow , shoulder , and low back , respectively , and 14 % , 20 % , and 22 % had more intense symptoms .  Women were more likely to be afflicted than men in all regions . In the full-fit multivariate logistic regression analysis , little influence on the timing of a rest pause and being disturbed by glare or reflection were significant predictors of shoulder symptoms , screen below eye height was a significant predictor for elbow symptoms , and previous symptoms was a significant predictor for symptoms in all regions . Computer worktime and psychosocial dimensions were not significant predictors . CONCLUSIONS Influence on work pauses , reduction of glare or reflection , and screen height are important factors in the design of future computer workstations . Since previous symptoms was a significant predictor of recurrent symptoms in all three regions under study , it can be concluded that musculoskeletal symptoms are persistent The United States MEPS ( musculoskeletal — eyestrain — psychosocial — stress ) study consisted of 1 group of 28 female data entry operators . The intervention was in 3 parts : workstation re design ( including advanced ergonomic chairs , motorized adjustable workstations , advanced adjustable keyboards , adjustable copyholders , adjustable footrests , monitor support surfaces ) and ergonomic training/coaching and corrective lenses . After the intervention , statistically significant reductions in physical signs ( trigger points , neck and shoulder mobility ) , subjective reports of intensity and frequency of musculoskeletal pain , and subjective reports of visual problems were observed . Static load during the work sample , as assessed by experts , improved after the intervention as did measured postural angles of head and trunk and subjective assessment of users of ergonomic characteristics of the workplaces . For all of these measures , improvements observed 1 month after intervention were also observed in the 1-year follow-up . Trapezius load , as assessed by electromyography ( EMG ) , decreased after intervention , but then increased in the follow-up . The increase was interpreted as a calibration problem 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 . Arm support markedly reduced muscle load in the neck-shoulder region among the operators . CONCLUSIONS The operators using video display units in this study preferred 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 Aims : To quantify the relative contribution of work related physical factors , psychosocial workplace factors , and individual factors and aspects of somatisation to the onset of neck/shoulder pain .  Methods : Four year prospect i ve cohort study of workers from industrial and service companies in Denmark . Participants were 3123 workers , previously enrolled in a cross sectional study , where objective measurement of physical workplace factors was used . Eligible participants were followed on three subsequent occasions with approximately one year intervals . Outcomes of interest were : new onset of neck/shoulder pain ( symptom cases ) ; and neck/shoulder pain with pressure tenderness in the muscles of the neck/shoulder region ( clinical cases ) . Results : During follow up , 636 ( 14.1 % ) participants reported neck/shoulder pain of new onset ; among these , 82 ( 1.7 % ) also had clinical signs of substantial muscle tenderness . High shoulder repetition was related to being a future symptom case , and a future clinical case . Repetition was strongly intercorrelated with other physical measures . High job dem and s were associated with future status as a symptom case , and as a clinical case . A high level of distress predicted subsequent neck/shoulder pain , and neck/shoulder pain with pressure tenderness . Conclusions : High levels of distress , and physical and psychosocial workplace factors are predictors of onset of pain in the neck and /or shoulders , particularly pain with pressure tenderness in the muscles Objectives : The aim of this intervention study was to determine the effects of an alternative mouse and /or a forearm support board on the change in upper body discomfort scores and the development of incident musculoskeletal disorders . Methods : This r and omised controlled intervention trial followed 206 engineers for one year . Participants were r and omised to receive ( 1 ) a conventional mouse only , ( 2 ) an alternative mouse only , ( 3 ) a forearm support board , or ( 4 ) an alternative mouse plus forearm support board . Outcome measures included weekly upper body discomfort scores and incident musculoskeletal disorders . Results : During the study , 42 participants were diagnosed with an incident musculoskeletal disorder . The group that received the forearm support board experienced a reduction in their right upper extremity discomfort ( beta-coefficient −0.35 , 95 % CI −0.67 to −0.03 ) in comparison to those who did not receive a forearm board . The group that received the alternative mouse had a protective , but non-significant ( p = 0.20 ) , effect on incident cases of right upper extremity musculoskeletal disorders ( HR 0.57 , 95 % CI 0.24 to 1.34 ) and a non-significant reduction in neck/shoulder discomfort ( beta-coefficient −0.23 , 95 % CI −0.056 to 0.10 ) in comparison to those who received a conventional mouse . Conclusions : In engineers who use a computer for more than 20 h per week , a forearm support board may reduce right upper extremity discomfort attributed to computer use OBJECTIVES A cross-sectional study was conducted to assess the association of upper extremity musculoskeletal disorders and work-related factors among employees using video display terminals at a large metropolitan newspaper . METHODS The study included 1050 r and omly selected workers from four departments . The workers were asked to complete question naires on symptoms , job tasks , and psychosocial and work organization conditions . Musculoskeletal disorders of the upper extremities were defined by frequency , duration , and intensity of symptoms not attributable to acute injury . Data were analyzed with the use of logistic regression . RESULTS A total of 973 workers completed the survey . The one-year period prevalence rate for any musculoskeletal disorder of the upper extremities was 41 % . Neck symptoms ( 26 % ) were the most frequently reported , followed by h and or wrist ( 22 % ) , shoulder ( 17 % ) , and elbow ( 10 % ) symptoms . Greater time working at the video display station was associated with increased h and or wrist symptoms in a dose-response relationship . In addition , variables corresponding to increased work-load dem and s ( eg , increased time working under deadline and increased job pressure ) were associated with increased neck , shoulder , and h and or wrist disorders . Women were more likely to report symptoms in several areas , but this finding may reflect the concentration of women in jobs involving more risk factors . CONCLUSIONS The results suggest a high prevalence of musculoskeletal disorders of the upper extremities among newspaper employees , and they provide additional evidence that increased work load , time pressure , and greater hours of computer use are related to the occurrence of work-related musculoskeletal disorders among these workers , particularly for disorders in the h and or wrist area
target: Limited evidence was also found for a causal relationship between  computer work per se and computer mouse time related to tension neck syndrome , but the evidence for keyboard time was insufficient .
  Insufficient evidence was found for an association between other musculoskeletal diagnoses of the neck and upper extremities , including shoulder tendonitis and epicondylitis , and any aspect of computer work .
  Conclusions There is limited epidemiological evidence for an association between aspects of computer work and some of the clinical diagnoses studied .
background: Background This review examines the evidence for an association between  computer work and neck and upper extremity disorders ( except carpal tunnel syndrome ) .