Select Awkward Postures and Work Duration Predict Musculoskeletal Symptoms Among Office Workers

Observed/self-reported neck rotation and self-reported neck extension were associated with neck/shoulder symptoms in a three-year prospective cohort study of Netherland office workers.  Findings also identified an adverse relationship between:

• self-reported long working days and neck/shoulder pain
• self-reported wrist flexion and arm/wrist/hand pain
• self-reported full-time work or longer and arm/wrist/hand pain

Neither neck/shoulder nor arm/wrist/hand symptoms were related to:

• observed/self-reported neck flexion
• self-reported wrist pronation
• observed arm elevation between 30 and 60 degrees
• self-reported duration of computer work

Data involving 398 office workers was drawn from a larger study of 1,742 workers that began in 1994.  Subjects were chosen based on job title (computer professional, administrative associate professional, and office clerk) assigned during prior data analysis which determined occupational classification from onsite inspections and video observation. 

Physical risk factor exposure was derived from a baseline questionnaire that asked about duration of wrist flexion/wrist pronation (prolonged periods of time – yes or no), duration of neck flexion/neck extension/neck rotation (prolonged periods of time – yes or no), the performance of computer tasks (never, occasionally, often or very often), duration of work week (less than 40 hours, 40 hours or more than 40 hours) and duration of work day (less than 8 ½ hours, 8 ½ hours or more). 

Analysis of worker videotapes was also performed to assess physical risk factor exposure.  At baseline, each worker was recorded for 10 to 14 minutes at four different times during one day.  After office workers were placed into one of 24 groups (based on tasks and physical loads as determined from onsite inspections), 25 percent of a group’s videotapes were analyzed.  All workers within a group were then assigned the mean value of the measured physical exposures (percentage of time subjects were working in neck flexion of 20 degrees or more, neck flexion of 45 degrees or more, neck rotation of 45 degrees or more and arm elevation of 30 to 60 degrees). 

Symptom information was gathered from the baseline questionnaire.  Subjects rated the occurrence of pain in the neck, shoulders, elbows, wrists or hands in the previous 12 months on a four point scale (never, sometimes, regular, prolonged).  A case was defined as regular or prolonged pain during the previous 12 months. 

Follow-up questionnaires were completed by subjects on a yearly basis over the subsequent three years.  The survey contained inquires on individual characteristics, job characteristics and musculoskeletal symptoms. 

Relationships were evaluated between the development of a case and the baseline observed posture, the self-reported posture described in the preceding 12 month questionnaire, duration of computer work, duration of working week, and duration of the working day.  Age, gender, job demands, social support of co-workers, decision authority and physical activity in leisure time were controlled as confounders. 

The prevalence of neck/shoulder symptoms declined each year from 38 percent at baseline to 23 percent in the final survey.  Similarly, the prevalence of arm/wrist/hand symptoms declined each year from 16 percent at baseline to 10 percent in the final survey.  Other significant study findings included the lack of relationship between:

• self-reported full-time work or longer and neck/shoulder pain
• self-reported long working days and arm/wrist/hand pain

The authors point out that the discrepancy in findings between self-reported and observed postures might be explained by the absence of observed posture data on all follow-up years. Information bias, according to van den Heuvel et al., could also have occurred with self-reporting in that those with symptoms might be more likely to classify themselves as assuming awkward postures.

Article Title: Do work-related physical factors predict neck and upper limb symptoms in office workers? 

Publication: International Archives of Occupational and Environmental Health 79: 585-592, 2006 

Authors: S G van den Heuvel, A J van der Beek, B M Blatter and P M Bongers