Effect of a dynamic office chair on spine biomechanics, calf circumference and perceived pain during prolonged sitting

Barrett, Matthew (2019) Effect of a dynamic office chair on spine biomechanics, calf circumference and perceived pain during prolonged sitting. Masters thesis, Memorial University of Newfoundland.

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Abstract

Background: Epidemiological studies suggest that prolonged static postures, such as those in sitting, are a risk factor for low back pain (LBP). Henceforth, increasing movement at sitting dominant work has been recommended. Objectives: To investigate the effects of a dynamic office chair on spine biomechanics, muscle activity, perceived pain, calf circumference, seat pressure data, as well as seat movement was compared to a control office chair. Methods: Thirty male participants were recruited for two, 3-hour sessions, which included a 2-hour standardized typing trial. Participants were block randomized to sit either in the dynamic or control chair on the first day. Spine angles, low back electromyography (EMG), perceived pain and calf circumference were measured pre and post typing trial. Results: Sitting in the dynamic chair resulted in significantly less spinal flexion (p = 0.039), significantly lower pain ratings (p=0.025), significantly decreased calf circumference measures (p < 0.001), significantly lower average seat pressure (p> 0.001), and significantly greater seat contact area (p=0.034) compared to the control chair after a 2 hour standardized typing trial. Low back EMG for all 6 muscles showed no significant differences between chair conditions (p=0.101, 0.115,0.173, 0.201, 0.248, 0.547). Conclusions: Participants sitting in the dynamic chair adopted a more upright posture, had lower levels of perceived LBP, and exhibited lower increases in calf circumference compared to the control chair. These results suggest the active chair is effective at decreasing several negative components associated with sitting for the occupant. Future work will replicate this design on a female population.

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