Research Review By Dr. Brynne Stainsby©

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Date Posted:

March 2021

Study Title:

Association of exposure to seated postures with immediate increases in back pain: A systematic review of studies with objectively measured sitting time

Authors:

De Carvalho DE, de Luca K, Funabashi M J et al.

Author's Affiliations:

Department of Community Health and Humanities, Faculty of Medicine, Memorial University of Newfoundland, Canada; Department of Chiropractic, Macquarie University, Sydney, Australia; Canadian Memorial Chiropractic College, Toronto, Canada; Centre for Biomechanics Research, AECC University College, Bournemouth, United Kingdom; Department of Rehabilitation Sciences, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, China; Sports Science and Clinical Biomechanics, University of Southern Denmark; Institute of Bone and Joint Research, The Kolling Institute, The University of Sydney, Sydney, New South Wales, Australia; Department of Rehabilitation Medicine, University of Alberta, Canada

Publication Information:

Journal of Manipulative and Physiological Therapeutics 2020; 43: 1-12.

Background Information:

Low back pain (LBP) is the leading cause of disability globally (1). Sitting for prolonged periods of time has been reported to be associated with LBP, regardless of whether an individual is currently experiencing an episode of LBP (2, 3). It has been hypothesized that there are a number of theoretical pathways whereby nociception could be initiated during seated posture, as sitting involves flexed postures between 50-97% of end range of motion (4-12). When tissues move towards end range, they are subject to increased levels of stress and strain. Once mechanical forces, such as tension, compression and strain, applied to the spine surpass thresholds, this can trigger nociceptive signals. As many spinal structures have nociceptors, there are mechanical scenarios that provoke a pain experience. There are number of studies that confirm the biological plausibility of these pathways to pain: Stretching of posterior passive tissues of the spine instigates inflammatory and cytokine responses (13); pain is perceived at lower thresholds when inflammation is present (14); spinal flexion creates stress at the peripheral third of the disc (secondary to the posterior migration of the nucleus) (15); and sustained low-level activation of the erector spinae muscles (during sitting) results in capillary compression and reduced oxygenation (16).

In experimental studies, perceived pain has been reported in young, healthy populations in response to sitting durations of greater than 1 hour (5, 6, 17-19), and sitting durations longer than 5 hours is predictive of recurrence of LBP (20). The data are unclear regarding occupational sitting as a risk factor for LBP, likely related to the high prevalence of both sitting and LBP, as well as the multifactorial nature of LBP (1, 21-25). It is also noted that the more specifically an exposure is documented (i.e. occupational sitting), the better the ability to observe an association with risk (26, 27). Thus, the purpose of this systematic review was to summarize the evidence regarding the association between objectively measured sitting time and immediate increase in perceived LBP.

Pertinent Results:

  • A total of 361 citations were screened and 75 potentially relevant articles were assessed for eligibility.
  • Ten articles (19, 28-36), including the data for 330 participants, were included in the final review. Eight studies were cross-sectional in design. Two studies were conducted in the field (32, 34) and the rest were conducted in a laboratory-controlled setting. Three studies (19, 31, 32) examined sitting in an automobile seat, while the remainder examined sitting in an office chair.
  • Durations of sitting ranged from 1 hour to 6.96 hours/day for 5 days. The duration of sitting in most studies (8/10) was between 1 and 3 hours.
  • In all but 1 study (35), pain ratings increased from baseline after the sitting exposure. It should be noted that the population in this study can be classified as obese (average body mass index of 31.9  5.0 kg/m2) (35), thus setting it apart from the populations of the remainder of the included studies.
  • Where presented, odds ratios (OR) of developing pain during the sitting exposures were greater than 1.
  • Five of the 10 studies (28, 31, 33, 35, 36) were identified as having an overall low risk of bias and five were rated as having a moderate risk of bias (19, 29, 30, 32, 34). A sensitivity analysis was conducted including only the five studies rated as having a low risk of bias.

Clinical Application & Conclusions:

This review identified that sitting for total durations ranging from 1-6.96 hours per day for five days is associated with immediate increases in LBP in people with and without clinical history of LBP. Although it has often been assumed that sitting aggravates existing cases of LBP, the current review found that sitting also resulted in increased levels of perceived pain in those without a history of LBP. It is important to note, however, that it is unknown whether this pain perception is clinically relevant, predictive of future significant LBP or simply a transient nuisance.

In six of the 10 studies, including both healthy and symptomatic participants, the increase in pain could be considered to surpass the threshold of minimal clinically important difference (an increase of more than 2 points on a 10-point scale/20 mm on a 100-mm scale). These studies were conducted in laboratory settings, as well as after 90 minutes of driving (32) and across five working days in a real office setting (34). This variability suggests these findings may be more generalizable than if all were found in the laboratory setting alone.

Importantly, the reviewers noted implications for future research, including studying subsets of populations, evaluating the longer-term impacts of increased pain perception after sitting, and methods for improving the estimates of sitting exposure. Expanding upon the current literature will improve the ability to determine the relationship between sitting and LBP.

Study Methods:

  • The systematic review examined the following research question: To determine whether sitting time measured objectively (by laboratory controlled time trial, direct observation, or wearable sensor) is associated with the immediate increase in LBP (determined by pain scale rating) in people > 18 years of age.
  • A systematic search strategy was developed by a health services librarian and was performed on four databases from inception to September 1, 2018 using keywords and subject headings. Additionally, reference lists of relevant articles were searched for completeness.
  • Eligible study design included observational studies and randomized controlled studies (only data from control sessions were included in this review). Included studies must have objectively measured sitting time and subjects must have reported on perceived LBP on a self-reported scale immediately or shortly after the exposure.
  • Two authors independently screened titles and abstracts.
  • Two authors then independently screened the full-text articles using standardized screening forms to identify relevant studies, using a third reviewer for consultation if necessary.
  • Two reviewers extracted data from included studies and built evidence tables.
  • After data extraction, two independent authors completed an assessment of reporting quality and risk of bias of the included articles using the Quality In Prognosis Studies tool. Overall risk of bias was assessed using low, moderate and high ratings.

Study Strengths / Weaknesses:

Strengths:
  • This study featured a clearly defined research question with a thorough and systematic literature search.
  • The review was registered prior to starting the project, and studies were not limited by language or publication date.
  • Independent screening of titles and abstracts, and full texts.
  • Only those trials assessed as being of high quality were included.
  • Two authors independently extracted the data from the included articles.
  • The reviewers provided a thoughtful reflection regarding the strengths and weaknesses of the review.
Weaknesses:
  • The primary limitation of this study relates more to the quality of the body of evidence than the methodology of the review itself. Although one study did include exposures up to 6.96 hours/day for 5 days, most studies were conducted in the laboratory setting, limiting the generalizability of the findings.
  • Although the authors used a validated tool to assess risk of bias, it was adapted to assess cross-sectional studies.
  • The sample sizes of the included studies were small, with each study having less than 100 participants.

Additional References:

  1. Hartvigsen J, Hancock MJ, Kongsted A, et al. What low back pain is and why we need to pay attention. Lancet 2018; 391(10137): 2356-2367.
  2. Damkot DK, Pope MH, Lord J, Frymoyer JW. The relationship between work history, work environment and low-back pain in men. Spine 1984; 9(4): 395-399.
  3. Majeske C, Buchanan C. Quantitative description of two sitting postures. With and without a lumbar support pillow. Phys Ther 1984; 64(10): 1531-1535.
  4. De Carvalho DE, Callaghan JP. Influence of automobile seat lumbar support prominence on spine and pelvis postures: a radiological investigation. Appl Ergon 2012; 43(5): 876-882.
  5. Dunk NM, Callaghan JP. Gender-based differences in postural responses to seated exposures. Clin Biomech 2005; 20(10): 1101-1110.
  6. Gregory DE, Dunk NM, Callaghan JP. Stability ball versus office chair: comparison of muscle activation and lumbar spine posture during prolonged sitting. Hum Factors 2006; 48(1): 142-153.
  7. Grondin DE, Triano JJ, Tran S, et al. The effect of a lumbar support pillow on lumbar posture and comfort during a prolonged seated task. Chiropr Man Therap 2013; 21(1): 21.
  8. Nairn BC, Azar NR, Drake JD. Transient pain developers show increased abdominal muscle activity during prolonged sitting. J Electromyogr Kinesiol 2013; 23(6): 1421-1427.
  9. O’Sullivan K, McCarthy R, White A, et al. Lumbar posture and trunk muscle activation during a typing task when sitting on a novel dynamic ergonomic chair. Ergonomics 2012; 55(12): 1586-1595.
  10. Schinkel-Ivy A, Nairn BC, Drake JD. Investigation of trunk muscle co-contraction and its association with low back pain development during prolonged sitting. J Electromyogr Kinesiol 2013; 23(4): 778-786.
  11. De Carvalho DE, Soave D, Ross K et al. Lumbar spine and pelvic posture between standing and sitting: a radiologic investigation including reliability and repeatability of the lumbar lordosis measure. J Manipulative Physiol Ther 2010; 33(1): 48-55.
  12. De Carvalho D. Spine Biomechanics of Prolonged Sitting: Exploring the Effect Chair Features, Walking Breaks and Spine Manipulation Have on Posture and Perceived Pain in Men and Women [Doctor of Philosophy]. Canada: University of Waterloo; 2015.
  13. Solomonow M. Ligaments: a source of musculoskeletal disorders. J Bodywork Mov Ther 2009; 13(2): 136-154.
  14. Ozaktay AC, Cavanaugh JM, Blagoev DC, et al. Effects of a carrageenan-induced inflammation in rabbit lumbar facet joint capsule and adjacent tissues. Neurosci Res 1994; 20(4): 355-364.
  15. Alexander LA, Hancock E, Agouris I, et al. The response of the nucleus pulposus of the lumbar intervertebral discs to functionally loaded positions. Spine 2007; 32(14): 1508-1512.
  16. McGill SM, Hughson RL, Parks K. Lumbar erector spinae oxygenation during prolonged contractions: implications for prolonged work. Ergonomics 2000; 43(4): 486-493.
  17. Fenety A, Putnam C, Walker JM. In-chair movement: validity, reliability and implications for measuring sitting discomfort. Appl Ergon 2000; 31(4): 383-393.
  18. Beach TA, Parkinson RJ, Stothart JP et al. Effects of prolonged sitting on the passive flexion stiffness of the in vivo lumbar spine. Spine J 2005; 5(2): 145-154.
  19. De Carvalho DE, Callaghan JP. Passive stiffness changes in the lumbar spine and effect of gender during prolonged simulated driving. Int J Ind Ergon 2011; 41(6): 617-624.
  20. da Silva T, Mills K, Brown BT, et al. Recurrence of low back pain is common: a prospective inception cohort study. J Physiother 2019; 65(3): 159-165.
  21. Lis AM, Black KM, Korn H, et al. Association between sitting and occupational LBP. Eur Spine J 2007; 16(2): 283-298.
  22. Hartvigsen J, Leboeuf-Yde C, Lings S et al. Is sitting while at work associated with low back pain? A systematic, critical literature review. Scand J Public Health 2000; 28(3): 230-239.
  23. Clemes SA, O’Connell SE, Edwardson CL. Office workers’ objectively measured sedentary behavior and physical activity during and outside working hours. J Occup Environ Med 2014; 56(3): 298-303.
  24. Jans MP, Proper KI, Hildebrandt VH. Sedentary behavior in Dutch workers: differences between occupations and business sectors. Am J Prev Med 2007; 33(6): 450-454.
  25. Kazi A, Duncan M, Clemes S, et al. A survey of sitting time among UK employees. Occup Med (Lond) 2014; 64(7): 497-502.
  26. National Research Council (US) and Institute of Medicine (US) Panel on Musculoskeletal Disorders and the Workplace. 2001.
  27. Punnett L, Wegman DH. Work-related musculoskeletal disorders: the epidemiologic evidence and the debate. J Electromyogr Kinesiol 2004; 14(1): 13-23.
  28. Li W, Yu S, Yang H, et al. Effects of long-duration sitting with limited space on discomfort, body flexibility, and surface pressure. Int J Ind Ergon 2017; 58: 12-24.
  29. Aota Y, Iizuka H, Ishige Y, et al. Effectiveness of a lumbar support continuous passive motion device in the prevention of low back pain during prolonged sitting. Spine 2007; 32(23): E674-677.
  30. Baker R, Coenen P, Howie E, et al. The short-term musculoskeletal and cognitive effects of prolonged sitting during office computer work. Int J Environ Res Public Health 2018; 15(8).
  31. Cardoso M, McKinnon C, Viggiani D, et al. Biomechanical investigation of prolonged driving in an ergonomically designed truck seat prototype. Ergonomics 2018; 61(3): 367-380.
  32. Cardoso M, Fulton F, McKinnon C, et al. Ergonomic evaluation of a new truck seat design: a field study. Int J Occup Saf Ergon 2019; 25(3): 331-343.
  33. Dunk NM, Callaghan JP. Lumbar spine movement patterns during prolonged sitting differentiate low back pain developers from matched asymptomatic controls. Work 2010; 35(1): 3-14.
  34. Foley B, Engelen L, Gale J, et al. Sedentary behavior and musculoskeletal discomfort are reduced when office workers trial an activity-based work environment. J Occup Environ Med 2016; 58(9): 924-931.
  35. Kowalsky RJ, Perdomo SJ, Taormina JM, et al. Effect of using a sit-stand desk on ratings of discomfort, fatigue, and sleepiness across a simulated workday in overweight and obese adults. J Phys Act Health 2018; 15(10): 788-794.
  36. Akkarakittichoke N, Janwantanakul P. Seat pressure distribution characteristics during 1 hour sitting in office workers with and without chronic low back pain. Saf Health Work 2017; 8(2): 212-219.

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