title: Field studies of comfort and discomfort in sitting. Musculoskeletal, visual and psychosocial stress in VDU operators before and after multidisciplinary ergonomic interventions. A 6 years prospective study--Part II. The association between psychological distress and musculoskeletal symptoms experienced by Chinese high school students. Effect of Four Computer Keyboards in Computer Users with Upper Extremity Musculoskeletal Disorders A Randomized Controlled Trial Evaluating the Effects of New Task Chairs on Shoulder and Neck Pain Among Sewing Machine Operators: The Los Angeles Garment Study A Randomized Controlled Trial of Chair Interventions on Back and Hip Pain Among Sewing Machine Operators: The Los Angeles Garment Study
abstract: A previous study defined sitting comfort and discomfort as independent entities associated with different factors : discomfort is related to biomechanics and fatigue factors , and comfort to a sense of well-being and aesthetics . In this study a checklist for evaluation of chair  comfort  and discomfort was analysed in two field studies . In the first study two groups of subjects , ten secretaries and ten managers , evaluated two groups of ten chairs . Subjects assessed each chair three times during a workday using three different types of scales . The results of a factor analysis reconfirmed the factor structure of comfort and discomfort . Analysis of variance demonstrated that discomfort was related to fatigue accumulated during the workday , but it was not related to chair design . There was no significant Chair x Time period interaction , which implies that the rank order of preference among a set of chairs was established during the first assessment and did not change during the day . In a second field study 37 secretaries used three different formats of a Chair Evaluation Checklist with 14 items . The results of a factor analysis again confirmed the factor structure of comfort and discomfort . Analyses of variance demonstrated that subjects can evaluate comfort and discomfort simultaneously without any halo-effect . The results have method ological implication s for measurement of comfort and discomfort . The findings for comfort , as defined , carry an important message that aesthetic design matters . This could provide a unifying focus for ergonomists and design ers 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 STUDY DESIGN A cross-sectional nonexperimental study . OBJECTIVES To determine the prevalence of musculoskeletal symptoms during a 6-month period and explore the contributing factors associated with these symptoms in Chinese senior class high school students . We also explored the relationship between psychological distress and musculoskeletal symptoms in this population . BACKGROUND Musculoskeletal symptoms with no underlying identifiable pathology are a management puzzle to medical professionals . Finding the prevalence of musculoskeletal symptoms is the first step in the prevention of further chronic pain syndromes in young adults . No study , however , has directly measured the prevalence of musculoskeletal symptoms in this population . Investigations of the contributing factors to these symptoms , though rare , can provide information to assist in the prevention of further injuries . METHODS The Musculoskeletal Symptom Question naire ( MSQ ) and the 12- question version of the Chinese Health Question naire ( CHQ-12 ) were r and omly distributed to students ( n = 550 ) in 4 different high schools in the Tainan area of Taiwan . Of these , 471 students returned the question naires for analysis . Descriptive statistics were computed for means , st and ard deviations , and frequencies . Chi-square statistics were used for analysis of the association between psychological distress and musculoskeletal symptoms . RESULTS The most frequent complaints of musculoskeletal symptoms among the adolescent Chinese student population were reported as being located in the following anatomical areas : neck ( 56 % ) , shoulder ( 45 % ) , and back ( 37 % ) . Based on the results from the CHQ-12 , all of the participants were divided into 2 groups : a high psychological ( CHQ-12 score > or = 5 ) and a low psychological ( CHQ-12 score < 5 ) distress group . There were significant differences of prevalence of musculoskeletal symptoms between these 2 groups ( P < .05 ) , especially for the neck region ( P = .003 ) . CONCLUSION The results showed that the prevalence of musculoskeletal symptoms was high in this adolescent population and demonstrated a certain association with psychological distress . We suggest that surveys of this type may serve as pre clinical detectors of future musculoskeletal disorders and may permit early interventions . Developing an intervention that addresses both physical and psychological problems may be beneficial for this population Eighty computer users with musculoskeletal disorders participated in a six-month , r and omized , placebo-controlled trial evaluating the effects of four computer keyboards on clinical findings , pain severity , functional h and status , and comfort . The alternative geometry keyboards tested were : the Apple Adjustable Keyboard ™ [ kb1 ] , Comfort Keyboard System ™ [ kb2 ] , Microsoft Natural Keyboard ™ [ kb3 ] and placebo . Compared to placebo , kb3 and to a lesser extent kb1 groups demonstrated an improving trend in pain severity and h and function following six months of keyboard use . However , there was no corresponding consistent improvement in clinical findings in the alternative geometry keyboard groups compared to the placebo group . Overall , there was a significant correlation between improvement of pain severity and greater satisfaction with the keyboards . These results provide evidence that keyboard users may experience a reduction in h and pain after several months of use of some alternative geometry keyboards Study Design . This is a 4-month r and omized controlled trial to evaluate the effect of chair design on neck/shoulder pain  among sewing machine operators . Objective . Determine whether a chair with a curved seat pan leads to improved changes in monthly neck/shoulder pain scores compared with a control intervention . Summary of Background Data . Sewing machine operators experience a high prevalence and severity of neck and shoulder pain in comparison to other working population s probably due to the sustained shoulder abduction and neck and upper back flexion required of the task . An adjustable height task chair that supports a forward sitting posture may reduce these posture-related risk factors and reduce neck/shoulder pain . Material s and Methods . A total of 277 sewing machine operators with neck/shoulder pain were assigned to receive 1 ) miscellaneous items ( control group ) , 2 ) a chair with a flat seat pan plus miscellaneous items , or 3 ) a chair with a curved seat pan plus miscellaneous items . Participants completed a monthly question naire assessing neck/shoulder pain severity . Results . Based on estimates of pain score changes from a repeat- measures linear regression , participants who received the flat seat chair experienced a decline in pain of 0.14 ( 95 % confidence interval , 0.07–0.22 ) points per month compared with those in the control group , while those who received the curved seat experienced a decline of 0.34 ( 95 % confidence interval , 0.28–0.41 ) points per month compared with those in the control group . These estimates did not change after adjustment for potential covariates . Conclusions . These findings demonstrate that an adjustable height task chair with a curved seat pan can reduce neck and shoulder pain severity among sewing machine operators Objective : Determine whether an adjustable chair with a curved or a flat seat pan improved monthly  back and hip pain scores in sewing machine operators . Methods : This 4-month intervention study r and omized 293 sewing machine operators with back and hip pain . The participants in the control group received a placebo intervention , and participants in the intervention groups received the placebo intervention and one of the two intervention chairs . Results : Compared with the control group , mean pain improvement for the flat chair intervention was 0.43 points ( 95 % CI = 0.34 , 0.51 ) per month , and mean pain improvement for the curved chair intervention was 0.25 points ( 95 % CI = 0.16 , 0.34 ) per month . Conclusions : A height-adjustable task chair with a swivel function can reduce back and hip pain in sewing machine operators . The findings may be relevant to workers who perform visual- and h and -intensive manufacturing jobs
target: Conclusion The findings of this review indicate a consistent trend that supports the role of a chair intervention to reduce musculoskeletal symptoms among workers who are required to sit for prolonged periods .
  The review also highlights gaps : for example in showing whether the effectiveness of a chair intervention has long-term impact , particularly with respect to musculoskeletal symptoms , as well as the recurrence of symptoms and the consequent cost of care
background: Background Prolonged sitting has been associated with musculoskeletal dysfunction .
  For desk workers , workstation modifications frequently address the work surface and chair .
  Chairs which can prevent abnormal strain of the neuromuscular system may aid in preventing musculo-skeletal pain and discomfort .
  Anecdotally , adjustability of the seat height and the seat pan depth to match the anthropometrics of the user is the most commonly recommended intervention .
  Within the constraints of the current economic climate , employers dem and evidence for the benefits attributed to an investment in altering workstations , however this evidence -base is currently unclear both in terms of the strength of the evidence and the nature of the chair features .
  The purpose of this study was to evaluate the evidence for the effectiveness of chair interventions in reducing workplace musculoskeletal symptoms .