Background: Computer work is generally associated with constrained postures and sedentary behaviors. Sit-stand tables have been suggested as an effective intervention to promote changes in gross body posture, and thus reduce sitting. However, few studies have addressed to what extent sit-stand table usage affects posture variation in other body regions. The aim of this study was to examine neck, trunk and arm postures among office workers with access to sit-stand tables.
Methods: Twenty-four office workers (16 females, 8 males; mean age 41 (SD9) years) participated. At entry, workers received sit-stand tables, which were then used for two months. Neck and trunk flexion, and right upper arm elevation (RUA) was recorded on three consecutive days, two hours/day, during the last week of table use. Minute-to-minute variability for the three postures during sitting (CWsit) and standing (CWstand) computer work was obtained for each participant. Job variance ratios (JVR) were calculated for the actual work, and for other combinations of CWsit and CWstand by simulation1.
Results: CWsit and CWstand were performed for 72% and 28% of the time spent at the computer. Minute-to-minute variability was larger in CWsit than in CWstand for all three postures, and the difference CWsit-CWstand was largest for RUA [median 1.7 (IQR −0.2–1.7)º], followed by trunk [1.6 (0.9–3.0)º] and neck [0.9 (0.0–3.1)º]. During actual work, JVR was between 1 and 3 for most participants. Simulations suggested that maximum variability would occur at a combination of 40–80% CWsit and 20–60% CWstand.
Conclusion: Neck, trunk and arm posture variation during computer work can be increased by manipulating proportions of time spent sitting and standing at a sit-stand table. The tentative “optimal” proportions reported here could be a benchmark for occupational health professionals.
2019.
10th International Scientific Conference on the Prevention of Work-related Musculoskeletal Disorders, 2-5 September 2019, Bologna, Italy