The following study explores how different sitting postures affect neck pain and muscle activity, especially slumped positions, which can lead to increased discomfort. Highlighting the importance of good posture, this research is a great reminder to be mindful of our sitting habits when spending long days in front of our computers. In addition to varying our positions, chiropractic care is effective in helping reduce neck pain and other musculoskeletal issues, reinforcing the valuable role of chiropractic care in promoting better spinal health. Read on to learn more

BACKGROUND INFORMATION:
There is a common belief that optimal and suboptimal spinal postures exist. However, the relationship between posture and musculoskeletal disorders is a controversial topic (1, 2). With neck pain specifically, a commonly considered risk factor includes sustained or awkward postures in combination with increased computer work time (3, 4). In office workers, forward head posture and altered axioscapular muscle activity is found more in those with neck pain compared to those without neck pain (5, 6). Despite this, it is difficult to ascertain if these differences in posture are causally related or coincidental.

In healthy populations, a short duration of computer work in a chair with a back rest can cause pain and discomfort (7). Furthermore, a flexed sitting position appears to cause higher activity of the cervical erector spinae muscles, as well as increased activity of the trapezius muscles (8). It is unclear though how pain intensity, pain sensitivity, and muscle activity may change with different sitting postures during a computer task.

This study set out to understand the immediate effect of different sitting postures during a standardized computer task on perceived pain in healthy participants. It was hypothesized that an upright sitting posture with forearm support would cause the least amount of pain, area of pain, and change in pain sensitivity when compared to sitting in a slumped posture without forearm support.

PERTINENT RESULTS:
There were 13 women and 12 men included with an average age of 27.4 years.

All the tasks that participants completed caused an increase in neck pain compared to baseline. The task of sitting slumped forward without forearm support caused the greatest peak increase in neck pain scores. Furthermore, compared to sitting upright with forearm supports, the pain pressure thresholds were 18% greater for the slumped position without forearm supports. As well, the slumped forward position without forearm supports was rated as significantly more difficult compared to the other tasks. The neck and shoulder were the most commonly identified areas of pain by participants, especially when sitting in a slumped forward position without forearm supports.

Interestingly, for the upper trapezius muscles, sitting upright with forearm supports caused 102.4% higher EMG values compared to sitting upright without forearm supports, and sitting in a slumped posture without forearm supports had resulted in 102.2% higher EMG activity compared to all the other tasks.

CLINICAL APPLICATION & CONCLUSIONS:
This study showed that a 15-minute seated computer task performed by a healthy population resulted in pain irrespective of the sitting posture, leading to the conclusion that there is no ideal sitting position. A slumped posture without forearm supports caused the greatest discomfort experienced by participants due to the high pain intensity, larger area of pain and increased perceived difficulty completing the task, as well as increased muscle activity compared to other postures. It was interesting to see that arm supports may not be as beneficial as previously thought, as the lowest muscle activity and pain intensity were for sitting upright without forearm supports.

Participants included in this study had relatively high pain levels with a median score of 2 or more, which is deemed to be a clinically relevant change from baseline. A possible reason for this is that participants who were included were not accustomed to the sustained load or strain experienced during this task. Participants were asked to sit in a predetermined posture without shifting which is something they may not typically do in their normal life. As well, no back rest was provided for any of the tasks and this could have an impact on the discomfort scores experienced.

It was not surprising to see that sitting slumped without forearm supports caused the greatest change in pain ratings, but it was surprising to observe that sitting upright without forearm supports caused lower pain intensities than sitting upright with forearm supports. This finding is in contrast to previous literature which found that forearm supports reduce discomfort (9, 10). A potential explanation for less pain experienced when sitting upright without forearm supports is that it may be mimic to a closer degree the participants’ habitual posture during their daily computer work.

Reviewer’s and Editor’s note: This study certainly may challenge some of our biases when it comes to posture. Although all postures in this study caused an increase in pain, some postures were better tolerated by participants than others. Bringing this into clinical practice, this paper supports the notion that instead of being in one sustained posture for a prolonged period of time, changing positions continuously throughout the workday will likely be beneficial to our desk-bound patients. We also have to consider that those with neck pain may see their condition or symptoms exacerbated even more, underpinning the importance of reminding our patients to vary their position throughout the day and take as many movement breaks as possible.

STUDY METHODS:
A convenience sample of 25 healthy, right-handed participants were recruited from a university setting. To be included, participants had to have normal, pain free active neck and shoulder ranges of motion. A Neck Disability Index (NDI) score of 10% was used as a screening tool to rule out any clinically relevant neck conditions.

The exclusion criteria included current neck or shoulder pain, currently pregnant, and any neurological, rheumatological or psychological conditions.

This study was a randomized crossover study conducted in a laboratory setting. There was a 5 minute washout period in between each task. Participants completed four different writing tasks, each lasting 15 minutes (no back supports for any of the following):

  • Sitting upright with forearm support
  • Sitting upright without forearm support
  • Sitting slumped with forearm support
  • Sitting slumped without forearm support

For the slumped forward position, the participant was instructed to sit as flexed as possible and stick out their chin to put their lumbar and thoracic spine in end range flexion with cervical extension.

In order to determine the order of the tasks, at the beginning of the session participants drew a concealed envelope containing their task order. This was randomized in advance by the assessor.

Participants were asked to rate their pain intensity using an 11-point numeric rating scale during every minute of the 15 minute task. Electromyography was also recorded during the task. Following the task a body chart was filled out with the perceived area of pain, as well as a Likert scale completed by the participant describing the perceived difficulty of the task. Pain pressure thresholds were measured bilaterally over the intermediate portion of the temporalis muscle and splenius capitis muscle, as well as the upper trapezius muscles.

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Please note that any advice in this article doesn’t replace personalized medical advice from a professional.

STUDY STRENGTHS / WEAKNESSES:

Strengths:

  • The study was a randomized crossover design where participants acted as their own controls. Potential order effects were mitigated via randomization of the four tasks.
  • Outcome measures included subjective scores as well as objective findings which provides a robust understanding of the impact these tasks have on individuals.

Weaknesses:

  • Participants were instructed to hold their posture but it is possible they changed their posture slightly during the task which may have impacted the findings.
  • The chair did not have a back rest which may have amplified perceived pain and resulted in a steeper increase in pain compared to normal office workers.
  • Participants were relatively young and therefore may not reflect findings in an older population.

AUTHOR’S AFFILIATIONS:
Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Denmark; Department of Physiotherapy, University College of Northern Denmark, Aalborg, Denmark; Department of Physiotherapy and Occupational Therapy, Aalborg University Hospital, Denmark

PUBLICATION INFORMATION:
Applied Ergonomics 2023; 104020.

Additional References
    Korakakis V, O’Sullivan K, Whiteley R, et al. Notions of "optimal" posture are loaded with meaning. Perceptions of sitting posture among asymptomatic members of the community. Musculoskelet Sci Pract 2021; 51: 102310.
    O’Sullivan K, O’Keeffe M. O’Sullivan L, et al. Perceptions of sitting posture among members of the community, both with and without non-specific chronic low back pain. Man Ther 2013; 18: 551–556.
    Brink Y, Crous LC, Louw QA, et al. The association between postural alignment and psychosocial factors to upper quadrant pain in high school students: a prospective study. Man Ther 2009; 14: 647–653.
    Jahre H, Grotle M, Smedbraten K, et al. Risk factors for non-specific neck pain in young adults. A systematic review. BMC Musculoskel Disord 2020; 21: 366.
    Chiu TT, Ku WY, Lee MH, et al. A study on the prevalence of and risk factors for neck pain among university academic staff in Hong Kong. J Occup Rehabil 2002; 12: 77–91.
    Szeto GPY, Straker L, Raine S. A field comparison of neck and shoulder postures in symptomatic and asymptomatic office workers. Appl Ergon 2002; 33: 75–84.
    Baker R, Coenen P, Howie E. The short term musculoskeletal and cognitive effects of prolonged sitting during office computer work. Int J Environ Res Publ Health 2018; 15.
    Caneiro JP, O’Sullivan P, Burnett A, et al. The influence of different sitting postures on head/neck posture and muscle activity. Man Ther 2010; 15: 54–60.
    Cook C, Burgess-Limerick R, Papalia S. The effect of upper extremity support on upper extremity posture and muscle activity during keyboard use. Appl Ergon 2004; 35: 285–292.
    Rempel DM, Krause N, Goldberg R, et al. A randomised controlled trial evaluating the effects of two workstation interventions on upper body pain and incident musculoskeletal disorders among computer operators. Occup Environ Med 2006; 63: 300–306.