Journal of the Ergonomics Society of Korea (대한인간공학회지)

Ergonomics Society of Korea (대한인간공학회)
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Development of Ergonomic Backrest for Office Chairs

  • Received : 2015.03.17
  • Accepted : 2015.03.27
  • Published : 2015.04.30
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Abstract

Objective: This study aims to develop and scientifically investigate the efficacy of the Spine S-curve Reactive Backrest that responds to the spine curvature of the user when seated, and maintains and enhances the natural S-curve of the lower back, thereby helping to relieve fatigue, correct posture and prevent spine deformities. Background: The focus of current development, design guidelines and/or standards for office chairs is mainly placed on the chair's dimensions, incline angle, adjusting features and lumbar support. Research and development was called for developing a chair backrest that maintains and improves the S-curve of the full spine. Method: The Spine S-curve Reactive Backrest was ergonomically designed to maintain correct posture and enhance user comfort. When leaned on, the backrest responds to the user's spine line and the whole lower back sits closely against the backrest, thereby aligning the user's lower back and backrest as one to maintain and improve the natural S-curve formation of the spine. In order to evaluate the efficacy of the newly designed chair (new design) and the comparison target (chair), five male college students of standard body type with normal spine curvature were selected as test subjects, and a motion analyzer and electromyography were utilized to measure S-curve and erector spinae muscle activity when seated. Results: The spine S-curve was better maintained and improved when sitting in the new design than in the comparison chair. Particularly notable was the greater displacement gap of the thoracic spine than the cervical spine, and also that of the lumbar more than the thoracic spine, with the increase of the backrest tilting angle. Furthermore, the electromyogram results showed the new design caused a lower fatigue level of the erector spinae muscles compared to the comparison chair, and also earned a higher preference in the subjective opinion results. Conclusion: The newly designed chair in this study responds to the user's spine curvature and maintains and enhances the lower back's natural S-curve, and thereby relieves fatigue, promotes better posture, and helps to prevent spine deformities better than existing office chairs. There is a need to widely introduce and supply this new design. Application: The new design is applicable to office and student chairs, and is expected to improve concentration and work efficiency.

Keywords

References

  1. Andersson, B.J. and Ortengren, R., Lumbar disc pressure and myoelectric back muscle activity during sitting II. Studies on an office chair, Scandinavian Journal of Rehabilitation Medicine, 6, 115-121, 1974.
  2. ANSI/HFES 100, American National Standards Institute and the Human Factors and Ergonomics Society, 2007.
  3. Basri, B. and Griffin, M.J., The vibration of inclined backrests: perception and discomfort of vibration applied normal to the back in the x-axis of the body, Journal of Sound and Vibration, 330(18-19), 4646-4659, 2011. https://doi.org/10.1016/j.jsv.2011.04.021
  4. Basri, B. and Griffin, M.J., Predicting discomfort from whole-body vertical vibration when sitting with an inclined backrest, Applied Ergonomics, 44(3), 423-434, 2013. https://doi.org/10.1016/j.apergo.2012.10.006
  5. Bendix, T., Poulsen, V., Klausen, K. and Jensen, C.V., What does a backrest actually do to the lumbar spine?, Ergonomics, 39, 533-542, 1996. https://doi.org/10.1080/00140139608964479
  6. BIFMA Ergonomics Guide G1, Business and Institutional Furniture Manufacturer's Association, 2002.
  7. Bishu, R.R., Hallbeck, M.S., Riley, M.W. and Stentz, T.L., Seating comfort and its relationship to spinal profile: a pilot study, International Journal of Industrial Ergonomics, 8, 89-101, 1991. https://doi.org/10.1016/0169-8141(91)90028-K
  8. BSR/HFES 100, Ergonomic Chair Recommendations & Ergonomic Chair Requirements, 2002.
  9. Carcone, S.M. and Keir, P.J., Effects of backrest design on biomechanics and comfort during seated work, Applied Ergonomics, 38(6), 755-764, 2007. https://doi.org/10.1016/j.apergo.2006.11.001
  10. Cartas, O., Nordin, M., Frankel, V., Malgady, R. and Sheikhzadeh, A., Quantification of trunk muscle performance in standing, semistanding and sitting postures in healthy men, Spine, 18, 603-609, 1993. https://doi.org/10.1097/00007632-199304000-00013
  11. CGSB-44.232, Canadian General Standards Board, 2002.
  12. Choi, B., Schnall, P., Yang, H., Dobson, M., Landsbergis, P., Israel, L., Karasek, R. and Baker, D., Sedentary work, low physical job demand, and obesity in US workers, American Journal of Industrial Medicine, 53(11), 1088-1101, 2010. https://doi.org/10.1002/ajim.20886
  13. Coleman, N., Hull, B.P. and Ellitt, G., An empirical study of preferred settings for lumbar support on adjustable office chairs, Ergonomics, 41, 401-419, 1998.
  14. Corlett, E.N. and Eklund, J.A., How does a backrest work?, Applied Ergonomics, 15, 111-114, 1984. https://doi.org/10.1016/0003-6870(84)90282-5
  15. CSA-Z412, Canadian Standards Association, 2000.
  16. Dolan, P., Adams, M.A. and Hutton, W.C., Commonly adopted postures and their effect on the lumbar spine, Spine, 13, 197-201, 1988. https://doi.org/10.1097/00007632-198802000-00012
  17. Dowell, W.R., An estimation of lumbar height and depth for the design of seating, Proceedings of the Human Factors Society 29th Annual Meeting, San Diego, CA., 1995.
  18. Dunk, N.M. and Callaghan, J.P., Gender-based differences in postural responses to seated exposures, Clinical Biomechanics, 20, 1101-1110, 2005. https://doi.org/10.1016/j.clinbiomech.2005.07.004
  19. Duoback Korea, http://www.duoback.co.kr (retrieved January 25, 2015).
  20. Ellegast, R.P., Kraft, K., Groenesteijn, L., Krause, F., Berger, H. and Vink, P., Comparison of four specific dynamic office chairs with a conventional office chair: Impact upon muscle activation, physical activity and posture, Applied Ergonomics, 43(2), 296-307, 2012. https://doi.org/10.1016/j.apergo.2011.06.005
  21. Gelb, D.E., Lenke, L.G., Bridwell, K.H., Blanke, K. and McEnery, K.W., An analysis of sagittal spinal alignment in 100 asymptomatic middle and older aged volunteers, Spine, 20, 1351-1358, 1995. https://doi.org/10.1097/00007632-199520120-00005
  22. Geyer, M.J., Brienza, D.M., Bertocci, G.E., Crane, B., Hobson, D., Karg, P. and Trefler, E., Wheelchair seating: A state of the science report, Assistive Technology, 15, 120-128, 2003. https://doi.org/10.1080/10400435.2003.10131896
  23. Groenesteijn, L., Vink, P., Looze, M.P. de. and Krause, F., Effects of differences in office chair controls, seat and backrest angle design in relation to tasks, Applied Ergonomics, 40(3), 362-370, 2009. https://doi.org/10.1016/j.apergo.2008.11.011
  24. Heydari, A., Nargol, A.V.F., Jones, A.P.C., Humphrey, A.R. and Greenough, A.G., EMG analysis of lumbar paraspinal muscles as a predictor of the risk of low-back pain, European Spine Journal, 19(7), 1145-1152, 2010. https://doi.org/10.1007/s00586-010-1277-1
  25. Hosea, T.M., Simon, S.R., Delatizky, J., Wong, M.A. and Hsieh, C.C., Myoelectric analysis of the paraspinal musculature in relation to automobile driving, Spine, 11, 928-936, 1986. https://doi.org/10.1097/00007632-198611000-00013
  26. ISO 9241- Part 5, International Standards Institute, 1999.
  27. Korea Patent 0328912, Waist-supporting device mounted on a chair, 2002.
  28. Lengsfeld, M., Frank, A., van Deursen, D.L. and Griss, P., Lumbar spine curvature during office chair sitting, Medical Engineering and Physics, 22, 665-669, 2000. https://doi.org/10.1016/S1350-4533(00)00086-2
  29. Lord, M.J., Small, J.M., Dinsay, J.M. and Watkins, R.G., Lumbar lordosis: effects of sitting and standing, Spine, 22, 2571-2574, 1997. https://doi.org/10.1097/00007632-199711010-00020
  30. Makhsous, M., Lin, F., Hendrix, R.W., Hepler, M. and Zhang, L.Q., Sitting with adjustable ischial and back supports: biomechanical changes, Spine, 28, 1113-1121, 2003.
  31. Oliver, C.W., Tillotson, K.M., Jones, A.P., Royal, R.A. and Greenough, C.G., Reproducibility of lumbar paraspinal surface electromyogram power spectra, Clinical Biomechanics, 11, 317-321, 1996. https://doi.org/10.1016/0268-0033(96)00020-4
  32. Park, S.J., Kim, C.H., Kim, C.J. and Lee, J.W., Comfortable driving postures for Koreans, International Journal of Industrial Ergonomics, 26(4), 489-497, 2000. https://doi.org/10.1016/S0169-8141(00)00020-2
  33. Porter, J.M., Interface pressure and the prediction of car seat discomfort, Applied Ergonomics, 30, 99-107, 1999. https://doi.org/10.1016/S0003-6870(98)00018-0
  34. Rohlmannt, A, Claes, L.E., Bergmannt, G., Graichen, F., Neef, P. and Wilke, H.J., Comparison of intradiscal pressures and spinal fixator loads for different body positions and exercises, Ergonomics, 44(8), 781-794, 2001. https://doi.org/10.1080/00140130120943
  35. Shibata, N. and Maeda, S., Determination of backrest inclination based on biodynamic response study for prevention of low back pain, Medical Engineering and Physics, 32, 577-583, 2010. https://doi.org/10.1016/j.medengphy.2010.02.007
  36. Sizekorea, http://sizekorea.kats.go.kr (retrieved December 12, 2014).
  37. Teknion, Responsive Back Technology (RBT) task chair, http://www.teknion.com (retrieved February 02, 2015).
  38. United States Patent 3938858, Chair with adjustable backrest, 1976.
  39. van Dieen, J., de Looze, M.P. and Hermans, V., Effects of dynamic office chairs on trunk kinematics, trunk extensor EMG and spinal shrinkage, Ergonomics, 44, 739-750, 2001. https://doi.org/10.1080/00140130120297
  40. Vergara, M. and Page, A., System to measure the use of the backrest in sitting-posture office tasks, Applied Ergonomics, 31, 247-254, 2000a. https://doi.org/10.1016/S0003-6870(99)00056-3
  41. Vergara, M. and Page, A., Technique to measure lumbar curvature in the ergonomic evaluation of chairs: description and validation, Clinical Biomechanics, 15, 786-789, 2000b. https://doi.org/10.1016/S0268-0033(00)00042-5
  42. Vergara, M. and Page, A., Relationship between comfort and back posture and mobility in sitting-posture, Applied Ergonomics, 33, 1-8, 2002. https://doi.org/10.1016/S0003-6870(01)00056-4
  43. Videman, T., Nurminen, M. and Troup, J., Lumbar spinal pathology in cadaveric material in relation to history of back pain, Spine, 15, 728-740, 1990.
  44. Wikipedia, http://en.wikipedia.org (retrieved January 10, 2015).