Overview
Keywords: Prolonged sitting; Discomfort; Spine
Timeline: 2010 - 2012
Researchers: Nadia Azar (University of Windsor), Janessa Drake (York University), Jack Callaghan (University of Waterloo)
Funder: Centre of Research Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD)
Project type: Seed grant
Sector/Workplace type: Sedentary
Theme:
Theme
1
Injury
mechanisms
Background/rationale
The trade-offs in spine angles and muscle activity that occur between the different regions of the spine, and their relationship to the development of discomfort may provide new insight into the development of spinal disorders during seated work.
Research questions/objectives/methods
In this study, regional spine postures and discomfort ratings were documented in five office workers on-site in their workplace over a two-hour period to evaluate how individuals normally sit during a workday and to observe movement patterns. Observations of the workstation layout and various temporal components of the task were used to develop a laboratory mock-up, in which 10 healthy male participants performed a standardized computer-based task for a two-hour period. Three-dimensional motion of the trunk and neck were captured using VICON motion analysis system, and bilateral surface electromyography was recorded from eight trunk muscles. Discomfort ratings were obtained every 15 minutes throughout the observation period.
Key findings
In both studies, the average spine angles within each spine region did not change significantly over the two hours, suggesting that participants maintained their initial postures. Several participants reported significant increases in discomfort ratings while others did not. Those that reported discomfort exhibited higher muscle activation levels in all muscles consistently across the two-hour prolonged sitting exposure.
Implications for the prevention of MSDs
These findings support a relationship between trunk muscle activity and pain development, with posture playing the role of modifier, during prolonged sitting.