Levels of evidence for interventions associated with positive effects were : Moderate evidence for arm supports ; and Limited evidence for ergonomics training plus workstation adjustments , new chair and rest breaks .
Levels of evidence for interventions associated with “ no effect ” were : Strong evidence for workstation adjustment alone ; Moderate evidence for biofeedback training and job stress management training ; and Limited evidence for cognitive behavioral training .
No interventions were associated with “ negative effects ” .
Conclusion It is difficult to make strong evidence d-based recommendations about what practitioners should do to prevent or manage upper extremity MSDs .
There is a paucity of high quality OHS interventions evaluating upper extremity MSDs and none focused on traumatic injury outcomes or workplace m and ated pre-placement screening exams .
Background Little is known about the most effective occupational health and safety ( OHS ) interventions to reduce  upper extremity musculoskeletal disorders ( MSDs ) and injuries .
Methods A systematic review used a best evidence synthesis approach to address the question : “ do occupational health and safety interventions have an effect on upper extremity musculoskeletal symptoms , signs , disorders , injuries , cl aims and lost time ? ”
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
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
Levels of evidence for interventions associated with positive effects were : Moderate evidence for arm supports ; and Limited evidence for ergonomics training plus workstation adjustments , new chair and rest breaks .
Levels of evidence for interventions associated with “ no effect ” were : Strong evidence for workstation adjustment alone ; Moderate evidence for biofeedback training and job stress management training ; and Limited evidence for cognitive behavioral training .
No interventions were associated with “ negative effects ” .
Conclusion It is difficult to make strong evidence d-based recommendations about what practitioners should do to prevent or manage upper extremity MSDs .
There is a paucity of high quality OHS interventions evaluating upper extremity MSDs and none focused on traumatic injury outcomes or workplace m and ated pre-placement screening exams .
Background Little is known about the most effective occupational health and safety ( OHS ) interventions to reduce  upper extremity musculoskeletal disorders ( MSDs ) and injuries .
Methods A systematic review used a best evidence synthesis approach to address the question : “ do occupational health and safety interventions have an effect on upper extremity musculoskeletal symptoms , signs , disorders , injuries , cl aims and lost time ? ”