Christensen S.1,2, Palsson T.1, Hirata R.1, Krebs H.1, Graven-Nielsen T.3
1Aalborg University, SMI, Department of Health Science and Technology, Aalborg, Denmark, 2University College of Northern Denmark, Department of Physiotherapy, Aalborg, Denmark, 3Aalborg University, Center for Neuroplasticity and Pain (CNAP), Aalborg, Denmark
Background: Neck and shoulder pain is common in the general population and is often linked with inappropriate sitting posture amongst office workers. Studying the effects of sitting posture on pain sensitivity in a healthy population will provide findings without confounding factors often present in a population already suffering from neck and shoulder pain.
Purpose: To investigate the immediate effect of sitting posture on perceived pain and pressure pain sensitivity.
Methods: Twenty-five healthy subject (12 women), mean age 27.4 (SD 5.5) years and BMI 24.0 (SD 3.2) kg/m2 were seated on a normal office work station adjusted according to the Danish recommendations for office workers. Subjects were not permitted to use the back support while performing a 15 min standardized typing task with four different postures:
1) Sitting upright with support of forearms,
2) Sitting upright without support of forearms,
3) Sitting slumped with support of forearms, and
4) sitting slumped without support of forearms.
The upright posture was explained as sit upright in a comfortable position while the slumped posture was explained as sit as flexed as possible and stick your chin out so you can see the screen. The order of the different postures was randomized in a balanced way and separated by a 5 min period in neutral position. Pressure pain thresholds (PPT) were recorded bilaterally over the temporalis (TEMP), splenius capitis (SC), upper trapezius (UT), and quadriceps femoris (QUAD) muscles. PPTs were collected at baseline and immediately after the four different sitting conditions. The pain intensity was recorded on a numerical rating scale (NRS) with 1 min intervals during each sitting condition.
Results: All experimental positions caused an increase in peak NRS scores compared with baseline (P 0.01). Sitting upright without support of forearms caused the lowest peak NRS (P 0.01) while the highest was found for sitting slumped without support of forearms (P 0.01) when compared to all other positions. Sitting slumped without support of forearms caused increased PPT at the SC site compared to all other sitting positions (P 0.05).
Conclusion(s): Local hypoalgesia in the neck was found following 15 min with the painful typing task. Sitting slumped without support of forearms seems to be the least ideal posture.
Implications: The current study shows the short-term effect of different sitting postures and typing tasks on pain intensity and sensitivity levels. A study investigating the effect of these specific sitting postures in office workers suffering from neck and shoulder pain would help the interpretations of the current findings.
Funding acknowledgements: This study was supported by Den Nordjyske Trivselsfond. CNAP is supported by the Danish National Research Foundation (DNRF121).
Topic: Musculoskeletal: spine
Ethics approval: This study was approved by the local ethics committee in Northern Denmark (N-20120018)
All authors, affiliations and abstracts have been published as submitted.
