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 ? ”
Computer terminal work and the benefit of microbreaks.
Microbreaks are scheduled rest breaks taken to prevent the onset or progression of cumulative trauma disorders in the computerized workstation environment . The authors examined the benefit of microbreaks by investigating myoelectric signal ( MES ) behavior , perceived discomfort , and worker productivity while individuals performed their usual keying work . Participants were r and omly assigned to one of three experimental groups . Each participant provided data from working sessions where they took no breaks , and from working sessions where they took breaks according to their group assignment : microbreaks at their own discretion ( control ) , microbreaks at 20 min intervals , and microbreaks at 40 min intervals . Four main muscle areas were studied : the cervical extensors , the lumbar erector spinae , the upper trapezius/supraspinatus , and the wrist and finger extensors . The authors have previously shown that when computer workers remained seated at their workstation , the muscles performing sustained postural contractions displayed a cyclic trend in the mean frequency ( MNF ) of the MES ( McLean et al. , J. Electrophysiol . Kinesiol . 10 ( 1 ) ( 2000 ) 33 ) . The data provided evidence ( p < 0.05 ) that all microbreak protocol s were associated with a higher frequency of MNF cycling at the wrist extensors , at the neck when microbreaks were taken by the control and 40 min protocol groups , and at the back when breaks were taken by the 20 and 40 min protocol groups . No significant change in the frequency of MNF cycling was noted at the shoulder . It was determined ( p < 0.05 ) that microbreaks had a positive effect on reducing discomfort in all areas studied during computer terminal work , particularly when breaks were taken at 20 min intervals . Finally , microbreaks showed no evidence of a detrimental effect on worker productivity . The underlying cause of MNF cycling , and its relationship to the development of discomfort or cumulative trauma disorders remains to be determined
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 ? ”