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Published on: March 23, 2019
Does prolonged seated deskwork alter the lumbar flexion relaxation phenomenon?
Samuel J Howarth1, Drazen Glisic, Joyce G B Lee
1Department of Graduate Education and Research Programs, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada M2H 3J1. showarth@cmcc.ca
Summary
Prolonged sitting may alter the low back flexion relaxation phenomenon (FRP), potentially increasing injury risk. This study found sitting increased the FRP onset angle, suggesting altered lumbar spine control after deskwork.
Area of Science:
- Biomechanics
- Occupational Health
Background:
- The flexion relaxation phenomenon (FRP) is a key aspect of lumbar spine stability.
- Sustained maximal lumbar flexion can alter the FRP, potentially impacting injury risk.
Purpose of the Study:
- To investigate if sub-maximal spine flexion from prolonged seated deskwork alters the FRP.
- To assess the impact of seated posture on lumbar spine control and stability.
Main Methods:
- Twenty-three participants underwent three flexion bouts with two 1-h seated deskwork periods.
- Lumbar spine kinematics and erector spinae electromyography were recorded.
- The angle of FRP onset was documented.
Main Results:
- Lumbar flexion at FRP onset increased significantly (1.3±1.5°) after 1 hour of sitting (p<0.05).
- No further increase in FRP onset angle was observed after 2 hours of sitting.
- Normalized FRP onset angle showed no significant change, suggesting posture-induced tissue deformation.
Conclusions:
- Prolonged seated posture may induce residual deformation in lumbar spine tissues.
- This deformation could challenge motor control and reduce the load-bearing capacity of the spine.
- Further research is needed to understand long-term implications for low back health.
