Research Article

Work an Unavoidable Pain in The Neck! Or Is It? A Systematic Review of Modifiable Risk Factors for Neck Pain in Office Workers

Jenny Alexanders¹, Jo Ann Kaye²*, Emma Skidmore³, Anthony Gordon¹ and Marc Johnson¹

¹School of Health and Social Care, Teesside University, UK

²Department of Sport and Exercise Science, Durham University, UK

³School of Health and Social Care, Nuffield Health, UK

Corresponding Author

Jo Ann Kaye, Department of Sport and Exercise Science, Durham University, UK.

Received Date: July 26, 2023;  Published Date:August 10, 2023

Background

In modern, industrialized countries, service and informationbased sectors are providing an increasing number of jobs [1-3]. Contemporary employment tendencies are becoming increasingly sedentary, leading to a growth in the office worker (OW) population [4,1]. The head and neck have been inculpated as the predominant painful body sites in OW [5]. Neck pain (NP) is defined as nonspecific, mechanical, or soft-tissue-related pain (excluding serious pathologies’ sequelae or disease, tumours, infection, and fractures) within the anatomical borders [6]. Studies have reported one-year prevalence of NP with exorbitances of 69% [7], compared to 37% within the general populace [8].

Occupational health services support employers and staff to manage work-related health, with specialist physiotherapists within the service. They aid work-related musculoskeletal disorders via physical treatments, preventative strategies regarding ergonomic advice, or exercise prescription for stress-management [9, 10]. Musculoskeletal disorders and stress form fundamental sickness absence rates [10], with 40% purportedly through musculoskeletal disorders such as NP amongst NHS employees [11]. NP corresponds with reduced work performance as it can reduce the ability to think and concentrate, which affects task engagement and results in productivity loss [1]. The COVID-19 pandemic has drastically metamorphosed working practices, as lockdown restrictions necessitated home environment changes for remote working [12, 13]. It has been identified that many home working environments possessed poor mental and musculoskeletal health and that 70.5% of participants reported current musculoskeletal pain – 23.5% in the neck. 50% of participants described that their symptom exacerbations related to their environmental alteration.

Plethoric research exists investigating work-related NP’s mutuality with the environment’s physical factors [14]. Prolonged sitting [15, 4], sitting in an unsupportive chair [16], and sitting in a bent, twisted, or sustained posture for prolonged periods [7] are all homologous with NP. Likewise, increased time working with computers [17-19] and using mice devices exacerbate risk [20]. However, as sitting is almost synonymous with computer-/ keyboard-/mouse-work (unless working from a standing desk), it may be a case of unravelling the relative risk of each factor and whether standing desks cause similar symptoms. Further larger scale research which explores a range of ergonomic working practices using standard desks, treadmill desks, and standing desks would provide valuable insight regarding neck pain prevenances in the office workforce.

Psychological factors, such as stress [16, 1, 21], and states of psychological distress concerning anxiety and depression [17, 1] are substantially correlated with NP. Additionally, perceived muscle-tension, a key physiological indicator of psychological symptoms [22], is substantiated to correlate with NP amongst computer workers [19]. Among female office workers, minimal supervisor-support and excessive job- strain have been proposed to have positive affiliations with neck symptoms and disability [20], whilst applaudable supervisor-support, decision-authority and skill- discretion are protective [23].

This study’s fundamental objective was to answer the research question ‘What modifiable factors affect the risk of developing neck pain in office workers?’.

Methodology

This study was a systematic review based on secondary data, therefore only an ethical release statement was required. The study protocol was approved by PROSPERO (CRD, 2020), the International Prospective Register of Systematic Reviews (reg – CRD42020204484), and is presented per PRISMA guidelines [24]. A positivist epistemological stance was assumed to uncover objective cause-and-effect relationships [25].

Search Strategy

PubMed, Medline, Embase, CINAHL, AMED, PEDro and SPORTDiscus online database searches were conducted in August 2020 to identify all published, peer-reviewed literature from biomedical, physiotherapy, Allied Health, and nursing disciplines.

Relevant studies and reviews reference lists were handsearched, and Google Scholar and Discovery were utilised to assist in the relevant literature’s identification. Population, exposure, outcome (PEO) framework was utilised to dissect the research question into relevant subcomponents and combined with relevant Boolean operators, search criteria were constructed for each database.

Eligibility criteria

For inclusion, studies must have disseminated findings relating to NP development and preventable factor-exposure. Observational methods designed to surmise cause- and-effect relationships were prioritised, therefore only longitudinal studies were utilised in the final synthesis. Participants must OW over the age of 18, without any other demographic or occupational characteristic restrictions.

Study Selection

All identified articles were transferred to RefWorks for management and de- duplication by the lead researcher (MJ). The remaining articles were subject to a two-stage screening process (Figure 1) with a second researcher contributing (LB) to minify bias risk [26]. Through the eligibility criteria, stage one of the screening process involved reading titles and abstracts, whilst stage two involved obtaining full-text copies of remaining studies and reading them exhaustively. Consensus regarding screening result differences was resolved through constructive discourse. If a study was found to have used the same sample as another under consideration, one was discarded following discussion, with the study deemed to be most relevant included. If consensus was unattainable, a third researcher (JAs) was available to contribute to a majority vote.

Study Appraisal

The Critical Skills Appraisal Programme (CASP) tool for cohort studies was employed to assess eligible studies bias-risks [27]. However, a paucity of gold-standard appraisal tools for specific study designs or Allied Health-use exist [28], and CASP tools have been critiqued as limited in their ability to fully represent the complex, nuanced methodological considerations used within different studies [29], risking subjective bias. This was negated through an additional researcher (JA), and disagreement was negotiated using a third (JAs). Completed appraisal checklists are presented in Appendix 1.

Data Extraction

Relevant data-extraction was performed using two specifically prepared forms. The first, to note methodological factors (Appendix 2), including study-design, follow-up length/frequency, sample selection criteria, definitions used, risk factor analysis, and data-collection methods. The second, notes each study’s sample characteristics, NP occurrence rates, and NP-associated factors (Table 1).

Table 1:Extracted results data.

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Results

1669 articles were identified via systematically searching the databases. Manual and hand-searching yielded nil supplementary articles. Following duplicate-removal and screening, 13 articles remained. 3 articles were discarded through methodological factors not meeting inclusion criteria, and 1 was excluded through low methodological quality. 8 articles meeting inclusion-criteria were included in the final synthesis (Figure 1)

Modifiable psychological factors

Intensified psychological stress increasing risk was divulged by three studies [30-32]. Korhonen et al. [33] reported finding a causative effect affiliated with high stress and inactivity. Paksaichol et al. [34] reported that perceived muscle-tension was predictive of NP development. Hush et al. [30] and Shahidi et al. [32] found an association with depression, anxiety and NP.

Modifiable work-social factors

Jensen [35] reported excessive cognitive demands and substandard technical support amongst men increased NP risk. In women, intolerable sensorial- stipulations, high-repetitiveness, low-influence, and inadequate social provisions elevated risk. Jun et al. [31] concluded that job-strain was related to increased-risk, however, high-control coping strategies and high social-support mediated this. Additional work-social factors include psychological job-demands [36], physical job- demands [34], and task difficulty [37].

Modifiable physical factors

Inappropriately-positioned computer monitors and keyboards were reported as physical risk factors [33-35]. Eltayeb et al. [37] reported factors relating to unsuitable posture-workstation interactions increased risk. Jun et al. [31] reported the risk-curtailing abilities of neutral thoracic posture and cervical flexor-endurance other physical factors increased computer-usage timescales [37].

Modifiable biomechanical factors

Greater cervical extensor-endurance has been considered preventative in the development of NP [31], whilst atrophic neck flexor-endurance was causative [34]. Whereas Sihawong et al. [36] advocated that neck extension-frequency throughout the workday increased neck pain association. Risk-reduction was purportedly interconnected with improving cervical-extension range-ofmotion by Jun et al. [31], and cervical flexion and extension range surpassing 120° by Hush et al. [30]. Paksaichol et al. [34] postulated that typing technique was a contributing factor in the development of neck pain.

The role of physical activity

Higher physical activity levels have been shown to reduce the risk of neck pain in office workers [31, 32]. Korhonen et al. [33] reported that office workers with higher levels of physical activity correlate with reduced stress levels and when compared to sedentary office workers, they were seven times more at risk of developing neck pain compared to highly active and extremely stressed office workers. Conversely, Hush et al. [30] reported that those exercising a few times a week had greater NP- occurrence risk. Furthermore, those who did exercise three times a week were also reported to spend considerable time working in a seated position and it was those sedentary behaviours that increased the risk of neck pain according to Jun et al. [30].

Discussion

The results demonstrate how work-social factors affect psychological stress, consequentially provoking neck pain development. Modifiable factors regarding physical environment, individuals’ physical capacities and activity profiles have been found. Psychologically, OW NP is associated with stress [1, 16, 21], general psychological distress [17], anxiety and depression [1] and perceived muscle-tension [19]. This data contained self-reported psychological symptoms therefore it may be susceptible to bias. Future research which uses a professionally assessed medical diagnosis will improve the robustness of the key findings.

Muscular tension was highlighted as causative of OW neck and shoulder pain by Huysmans et al. [38]. However, laboratorybased findings do not associate objectively measured muscular tension with pain. Stress/pain reporting is also more likely by those experiencing muscle-tension, perhaps resulting from other factors.

Consequently, objective determination that stress within office scenarios influences muscle-tension, and NPs are recommended.

Kraatz et al. [39] exhibited compelling evidence for jobdemands, -control, -strain and social-support relationships in general working populations. NP-variable correlations of various work related demands [40], include control [41], support [23], and strain [41]. OW may avoid reporting negative work-social facture for fear of repercussions which may further increase stress. Preventative strategies focused on reducing job-strain, demand, and optimising job-control and social-support could reduce social domain’s detrimental repercussions.

OW have more risk of having NP if they are more physically active [4], with elevated vulnerability in less active [21], and sedentary populations [4, 15]. Sitthipornvorakul et al. [42] reported that those working sedentary jobs could minify NP’s risk by 14% by increasing their physical activity via walking 1000 steps-perday. Opposing to this, Blangstead et al. [43] stated that all-round training (cardiopulmonary-focused exercise) did not precipitate protective OW neck and shoulder symptom effects.

Hildebrandt et al. [44] reported that certain ‘vigorous’ sports retained increased risk. This infers that the physical activity modality is influential and may account for this review’s contradictory finding that exercising 3+ times-per-week increases risk.

Physiotherapists are perfectly placed to inhibit NP via exercise intervention. Wu et al. [45] found a dose-response relationship between exercise frequency and resistance to job-stress. Workplace exercise interventions such as yoga [46], outdoor aerobic/strength [47], and tai chi [48,49] have demonstrated positive effects on stress.

Inappropriately set computer monitors as a cause of NP is well recognised [50]. Some studies have used unclear or undefined measures of optimal/sub-optimal. For example, Jensen [35] reported that having a high-placed screen was causative, whilst Paksaichol et al. [34] did not specify high/low positioning specifically. These inconsistencies necessitate a wider study area to aid more indisputable understandings.

Low-placed screens significantly increase neck loading [51] and muscle-activity [52]. Prolonged neck-flexion is also associated with NP in OWs and NP’s association [16]. Muscle-strain with cervical extension has also been associated with high-placed screens [53]. Future research is warranted to determine whether optimal screenheight interventions prevent the onset of NP.

NP is purportedly associated with reduced activity, strength and/or endurance of cervical-extensors [32, 54, 55], -flexors [56- 58] and reduced force-production capacity in all motional planes [57]. Furthermore, minimal neck/shoulder physical capacity was found as an NP risk factor by Hamberg-van Reenen [59]. Falla et al [57, 59] studies investigating cervical-flexor musculature ascertained that pain- inducing neck postures amongst computerusers are rectifiable.

Sihawong et al. [36] preventative intervention study integrated static stretches and muscle-activation to significantly improve neck flexor-endurance and cervical- mobility, which reduced NP cases by 55%. This suggests that tight/weak muscular structures are analogous with NP. Future research determining why cervicalbiomechanical structures affected are compromised would benefit the evidence base. Physiotherapists are perfectly placed to contribute to NP prevention by leading interventions aimed at improving cervical-biomechanical efficiency.

Strengths And Limitations

The methodology was approved by PROSPERO [60, 61] before inception to increase credibility. The process was characterised by elements via systematic search process, additional researchers contributed to screening and appraisal, and implemented a vindicable appraisal tool. It adhered to PRISMA guidelines, increasing robustness. This produced eight high-quality studies’ synthesis, with high ecological validity and conclusions of causeand- effect with clinical implications.

The search was limited to studies published in English, possibly creating publication bias. The CASP appraisal tool was found by both appraisers to rely on subjective interpretation, referring to both the guidance for use and checklist items. This was reflected in different appraiser responses, despite results being broadly similar, the tool also uncovered a lack of representative samples, which, percase, limits the conclusions’ practical applications. Finally, the synthesised studies incorporated significant methodological heterogeneity, perhaps explaining the studies’ widely varied results, possibly influencing the conclusions reached here. Therefore, future research is required to confirm the proposed assertions.

Conclusion

OW are exposed to specific factors that promote NP’s development. Discernment of these factors may assist in NP’s prevention and treatment. Contemporary trends towards office work, and the potential for large workforce exposure to similar risk factors, following the necessitated homeworking during the Covid-19 pandemic, denotes that substantial quanta of the working population may be at risk of developing avoidable NP.

This review has explored modifiable risk factors to address NP’s negative effects. Evidence exists that psychological factors vis-à-vis stress and distress may be decisive causative factors, potentially influenced by work-social factors apropos job- demands, -control, -support, and -strain. Auspiciously, physiotherapeutic advice, exercise recommendations, and general physical activity may yield preventative effects against psychologically induced NP. Physiotherapists, including those within occupational health, are ideally situated to prevent and treat OW NP.

The evidence infers that incongruously positioned screens have causative sequelae, perhaps due to neck angle-related ramifications. Although heterogeneity exists concerning what height is inappropriate, there appears to be a consensus that screen tops should be at eye-level. Furthermore, the finding that sub-optimal cervical biomechanics are causative, strengthens the evidence base. With consideration of the studies’ limitations, the findings of this review may contribute to further scientific enquiry and evidence-based OW NP prevention and treatment stratagems inaugurations.

Funding

There are no sources of funding.

Conflict of Interest

There are no conflicts of interest.

Acknowledgement

None.

References

1. Frutiger M, Taylor T, Borotkanics RJ (2019) Self-reported Non-Specific Neck Pain (NSNP) is associated with presenteeism and biopsychosocial factors among office workers. Int J Workplace Health Manag 12(4): 214-227.
2. Ostry A (2000) From Chainsaws to Keyboards: Injury and Industrial Disease in British Columbia. Vancouver, CANADA: UBC Press.
3. Straker L, Mathiassen SE (2009) Increased physical workloads in modern work - a necessity for better health and performance?. Ergonomics 52(10): 1215-1225.
4. Cagnie B (2007) Individual and work-related risk factors for neck pain among office workers: a cross sectional study. European Spine J 16(5): 679-686.
5. Janwantanakul P (2008) Prevalence of self-reported musculoskeletal symptoms among office workers. Occupational Medicine 58(6): 436-438.
6. Guzman J (2008) A New Conceptual Model of Neck Pain. Spine 33(4): 14-23.
7. De Loose V (2008) Prevalence and Risk Factors of Neck Pain in Military Office Workers. Military Med 173(5): 474-479.
8. McLean SM (2010) Risk factors for the onset of non-specific neck pain: a systematic review. J. Epidemiology Community Health 64(7): 565-572.
9. (2012) The Chartered Society of Physiotherapy Under Pressure. Stay healthy and happy at work with advice from the Chartered Society of Physiotherapy.
10. (2017) The Chartered Society of Physiotherapy Occupational health.
11. (2013) The Chartered Society of Physiotherapy Fit enough for patients? An audit of workplace health and wellbeing services for NHS staff.
12. Bonaccorsi G (2020) Economic and social consequences of human mobility restrictions under COVID-19. Medical Letter on the CDC & FDA 117(27): 15530-15535.
13. Moretti A (2020) Characterization of Home Working Population during COVID-19 Emergency. A Cross-Sectional Analysis. Int J Environ Res Public Health 17(17): 6284.
14. Gooch JW (2011) Encyclopedic Dictionary of Polymers NY: Springer.
15. Ariëns GAM (2001) Are neck flexion, neck rotation, and sitting at work risk factors for neck pain? Results of a prospective cohort study. Occup Environ Med 58(3): 200-207.
16. Celik S (2018) Determination of pain in musculoskeletal system reported by office workers and the pain risk factors. Int J Occup Environ Health 31(1): 91-111.
17. Chen X, O’Leary S, Johnston V (2018) Modifiable individual and work-related factors associated with neck pain in 740 office workers: a cross-sectional study. Braz J Phys Ther 22(4): 318-327.
18. Darivemula SB (2016) Work-related neck pain among desk job workers of tertiary care hospital in New Delhi, India: Burden and determinants. Indian Journal of Community Medicine 41(1): 50-54.
19. Griffiths KL (2012) Prevalence and risk factors for musculoskeletal symptoms with computer-based work across occupations. Work 42(4): 533-541.
20. Johnston V (2008) Associations between individual and workplace risk factors for self- reported neck pain and disability among female office workers. Applied Ergonomics 39(2): 171-182.
21. Hasanat RM (2017) Frequency and associated risk factors for neck pain among software engineers in Karachi, Pakistan. JPMA 67(7): 1009-1012.
22. Bongers PM (2006) Epidemiology of work-related neck and upper limb problems: Psychosocial and personal risk factors (Part I) and effective interventions from a bio behavioural perspective (Part II). Journal of Occupational Rehabilitation 16(3): 279-302.
23. Johnston V (2010) Interactive effects from self-reported physical and psychosocial factors in the workplace on neck pain and disability in female office Workers. Ergonomics 53(4): 502-513.
24. Moher D (2009) Preferred Reporting Items for Systematic Reviews and Meta- Analyses: The PRISMA Statement. PLoS Medicine 6(7).
25. Scotland J (2012) Exploring the Philosophical Underpinnings of Research: Relating Ontology and Epistemology to the Methodology and Methods of the Scientific, Interpretive, and Critical Research Paradigms. English Language Teaching 5(9): 9.
26. Davies A (2019) Carrying out systematic literature reviews: an introduction. Br J Nurs 28(15): 1008-1014.
27. (2018) Critical Skills Appraisal Programme CASP Cohort-Study Checklist.
28. Katrak P, Andrea E Bialocerkowski, Nicola Massy Westropp, VS Saravana Kumar, Karen A Grimmer, et al. (2004) A systematic review of the content of critical appraisal tools. BMC Medical Research Methodology 4(1): 22.
29. Long HA, French DP, Brooks JM (2020) Optimising the value of the critical appraisal skills programme (CASP) tool for quality appraisal in qualitative evidence synthesis. BMC Medical Res. Methodol 1(1): 31-42.
30. Hush JM (2019) Individual, physical and psychological risk factors for neck pain in Australian office workers: a 1-year longitudinal study. Eur Spine J 18(10): 1532-1540.
31. Jun D (2020) A Longitudinal Evaluation of Risk Factors and Interactions for the Development of Nonspecific Neck Pain in Office Workers in Two Cultures. Human Factors 63(4): 663-683.
32. Shahidi B, Curran Everett D. Maluf KS (2015) Psychosocial, Physical, and Neurophysiological Risk Factors for Chronic Neck Pain: A Prospective Inception Cohort Study. J Pain 16(12): 1288-1299.
33. Korhonen T, R Ketola, R Toivonen, R Luukkonen.E Viikari Juntura, et al. (2003) Work related and individual predictors for incident neck pain among office employees working with video display units. J. Occup Environ Med 60(7): 475-482.
34. Paksaichol A, Lawsirirat C, Janwantanakul P (2015) Contribution of biopsychosocial risk factors to nonspecific neck pain in office workers: A path analysis model. J Occup Health 57(2): 100-109.
35. Jensen C (2003) Development of neck and hand-wrist symptoms in relation to duration of computer use at work. Scand J Work Environ Health 29(3): 197-205.
36. Sihawong R (2016) Predictors for chronic neck and low back pain in office workers: a 1-year prospective cohort study. J Occupa Health (1): 16-24.
37. Eltayeb S (2009) Work related risk factors for neck, shoulder and arms complaints: a cohort study among Dutch computer office workers. J Occup Rehab 19(4): 315-322.
38. Huysmans MA, Blatter BM, Ván Der Beek AJ (2012) Perceived muscular tension predicts future neck-shoulder and arm-wrist-hand symptoms. 69(4): 262-267.
39. Kraatz S (2013) The incremental effect of psychosocial workplace factors on the development of neck and shoulder disorders: a systematic review of longitudinal studies. J Occup Health 86(4): 375-395.
40. Kaliniene G (2013) Associations between neck musculoskeletal complaints and work-related factors among public service computer workers in Kaunas. International J Occup Med Enviro Health 26(5): 670-681.
41. Johnston V (2007) Interaction of psychosocial risk factors explain increased neck problems among female office workers. Pain 129(3): 311-320.
42. Sitthipornvorakul E, Janwantanakul P, Lohsoonthorn V (2015) The effect of daily walking steps on preventing neck and low back pain in sedentary workers: a 1-year prospective cohort study. European Spine J 24(3): 417-424.
43. Blangstead, Karen Søgaard, Ernst A Hansen, Harald Hannerz, Gisela Sjøgaard, et al. (2008) One-year randomized controlled trial with different physical-activity programs to reduce musculoskeletal symptoms in the neck and shoulders among office workers. Scan J Work Environ Health 34 (1): 55-65.
44. Hildebrandt VH (2000) The relationship between leisure time, physical activities and musculoskeletal symptoms and disability in worker populations. J Occup Health 73(8): 507-518.
45. Wu YH (2016) FREQUENT EXERCISE MODIFIES JOB STRESS RELATED BURN-OUT. J Occup Health (73): A212-A213.
46. Lin S (2015) Effects of Yoga on Stress, Stress Adaption, and Heart Rate Variability Among Mental Health Professionals—A Randomized Controlled Trial. Worldviews on Evidence-Based Nursing 12(4): 236-245.
47. Calogiuri G, Katinka Evensen, Andi Weydahl, Kim Andersson, Grete Patil, et al. (2016) Green exercise as a workplace intervention to reduce job stress. Results from a pilot study. Work 53(1): 99-111.
48. Zheng S, Sara Lal, Peter Meier, David Sibbritt, Chris Zaslawski, et al. (2018) The Effects of Twelve Weeks of Tai Chi Practice on Anxiety in Stressed but Healthy People Compared to Exercise and Wait‐List Groups–A Randomized Controlled Trial. J Clinl Psychology 74(1): 83-92.
49. Herring MP, O’Connor PJ, Dishman RK (2010) The Effect of Exercise Training on Anxiety Symptoms Among Patients: A Systematic Review. Archives of Internal Med 170(4): 321-331.
50. Fogleman M, Lewis RJ (2002) Factors associated with self-reported musculoskeletal discomfort in video display terminal (VDT) users. International Journal of Industrial Ergonomics 29(6): 311-318.
51. Svensson HF, Svensson OK The Influence of The Viewing Angle on Neck-load During Work with Video Display Units. J Rehabi Med 33(3): 133-136.
52. Turville KL (1998) The effects of video display terminal height on the operator: a comparison of the 15° and 40° recommendations. Applied Ergonomics 29(4): 239-246.
53. Straker L (2009) Effect of visual display height on modelled upper and lower cervical gravitational moment, muscle capacity and relative strain. Ergonomics 52(2): 204-221.
54. O'Leary S, Barbara Cagnie, Ashton Reeve, Gwendolen Jull, James M. Elliott, et al. (2011) Is There Altered Activity of the Extensor Muscles in Chronic Mechanical Neck Pain? A Functional Magnetic Resonance Imaging Study. Archives of Physical Med Rehab 92(6): 929-934.
55. Rezasoltani A (2010) Preliminary study of neck muscle size and strength measurements in females with chronic non-specific neck pain and healthy control subjects. Manual Thera 15(4): 400-403.
56. Falla DL, Jull GA, Hodges PW (2004) Patients with neck pain demonstrate reduced electromyographic activity of the Deep cervical flexor muscles during performance of the craniocervical flexion test. Spine 29(19): 2108-2114.
57. Falla D (2006) An endurance-strength training regime is effective in reducing myoelectric manifestations of cervical flexor muscle fatigue in females with chronic neck pain. Clinical Neurophysiology 117(4): 828-837.
58. Ylinen J, Petri Salo, Matti Nykänen, Hannu Kautiainen, Arja Häkkinen, et al. (2004) Decreased isometric neck strength in women with chronic neck pain and the repeatability of neck strength measurements. Archives Phys Med Rehab 85(8): 1303-1308.
59. Hamberg van Reenen HH, B M Blatter, J W R Twisk, W van Mechelen, P M Bongers (2010) Physical capacity in relation to low back, neck, or shoulder pain in a working population. Occup Enviro Med 63(6): 371-377.
60. Falla D, Gwendolen Jull, Trevor Russell, Bill Vicenzino, Paul Hodges, et al. (2007) Effect of Neck Exercise on Sitting Posture in Patients with Chronic Neck Pain. Physical Therapy 87(4): 408-417.
61. (2021) Centre for Reviews and Dissemination. PROSPERO: International prospective register of systematic reviews.