INTRODUCTION
The suitability of school chairs has demanded a wider interest in the past few years than ever before (1)(2). Considering the highlighted statistical association between posture and back pain (3), the sitting habits of the child has a significant impact on the health of their spine and back. Troup et al. (4) showed that back pain in childhood is a strong predictor of such symptoms in adulthood. Moreover, it is widely accepted that back pain is a significant burden on the health systems of industrialised countries (5), commonly giving rise to disc bulge pathologies and resultant time off work (6). Herniation of the intervertebral discs in children and teenagers is exceedingly rare (7), despite the progressive alterations in the annulus fibrosus and nucleus pulposus occurring with age (8). However, poor posture when seated is a significant risk factor for disc and facet joint degeneration later in life (9). Given children are spending over 50-70% of their 6-hour school day sitting down (10)(11), it is imperative that greater consideration is given to solving this growing issue. This article will discuss how posture impacts spinal health in children, how poor sitting habits can manifest and two proposed changes to school furniture: ergonomically designed chairs and “sit-stand desks”.
Sitting Posture and Back Pain:
Sitting posture has often been addressed when patients present with back pain. Murphy et al. (5) used the Portable Ergonomic Observation Method (12) to record the real-time posture of 66 children. Significant associations were observed between flexed trunk position of more than 20° and lower back pain; also associated were static postures and the prevalence of neck pain. The Portable Ergonomic Observation Method is more favourable for an investigation of this nature (compared to time-sampled observations: Posturegram (13) and OWAS (14)) because it provides information about the duration, magnitude and frequency of any given posture. The positive correlation between the slumped posture observed and the initiation of lower back pain could be resultant of the tensing in the posterior muscle fibres (5). Both Sanjeevi (15) and Bendix (16) have suggested that lower back pain could be attributed to a lack of collagen-fibre elasticity. Consequently, the question of suitable furniture may not only have implications on the posture of children in schools, but also the causation of upper and lower back pain.
Postural Related Back Pain; The Implications:
It has been suggested that back pain amongst children is rare; Turner et al. (17) found that just 2% of referrals in an under 15’s group accounted for this. However, more recent epidemiological studies have highlighted that the occurrence of back pain in youths has risen to a much higher prevalence (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). A staggering 51% cumulative presence of back pain by the age of 20 was reported by Troussier et al. (29); so, whilst adult workers are not recommended to sit for more than 4 hours per shift to prevent back pain (30), new recommendations for children in schools are needed. Furthermore, children with lower back pain have been shown to frequently carry this forward into their adult life (31)(32). Due to the relative orientation of adjacent vertebrae being directed by posture, it has been concluded that posture has the power to overwhelmingly alter the stress distribution within the intervertebral discs (33) and apophyseal joints (34)(33), often resulting in intervertebral disc and apophyseal injures (6). This abnormal distribution is further exaggerated by “creep” loading- the normal compression of the vertebrae gradually throughout the day as the intervertebral discs loose hydration (6) by 1-2mm (35).It should be noted that though disc and spinal traction apophyseal injures in children are rare (7), poor posture is a significant risk factor for disc and facet joint degeneration later in life (9).Consequently, if the symptoms were identified and remedied with advantageous posture in their initial onset during childhood, then the incidence of adult chronic back pain may be greatly reduced. The need to address the root cause of this escalating issue has never been more significant.
A major concern to public health is upper neck and back pain (36); despite extensive study of the effect of this in adults, more research needs to be done into the causation of early onset pain in childhood so that preventative measures can be curated. In the 2017 study by Fares et al. (36) 100% of the 180 children reported excessive flexion of their necks when using screens or tablets seated. Although only 87% of these individuals were diagnosed with musculoskeletal pain at the neck and upper back (36), many will go on to develop postural-related pain later in life (possibly resulting in facet joint and intervertebral disc pathologies (6)). I would suggest that often children overlook the long-term damage posture could cause to musculoskeletal health because the short-term effects are undetected. Latalski et al. (24)reported that no statistically significant relationships were observed between the postural defects detected at school and posture at home. However, this research was focused on a sample of 380 14-year-olds and more research would need to be done to determine if these correlations are reflective of all ages. There was a positive relationship which must be highlighted: between increased physical activity levels and decreased prevalence of postural defects (24). This potential solution for reducing the occurrence of postural deficiency is furthered by the 2006 summary of European Guidelines for Prevention of Low Back Pain, concluding that: despite there being insufficient evidence for the recommendation of any specific furniture to prevent low back pain, physical exercise has been shown to have an advantageous effect on standing and sitting postures (37). The impact of poor posture on the upper body can seriously affect quality of life in adulthood and therefore efforts should be made to ameliorate the cause.
Ergonometric Furniture:
Authors have begun to design and investigate various ergonometric chairs for school pupils (38)(39)(40)(41)(42). However, there is still considerably more research into adult ergonomic seating than there is available for children; this lack of data will hinder the progression of designs in this area significantly. During the period of time spent seated in school, there are two predominant positions: leaning backwards (resting and watching) and leaning forwards (writing and reading) (42). The majority of research into sitting posture focuses on subjects leaning forwards, perhaps because this is the posture most adults adopt at desks and seated workstations. Conversely, it is for this reason that data from adult based investigations are not descriptive of children.
From the data that is available, numerous authors have used comparable questionnaires; the aim being to determine the efficacy of prototype chairs (40)(41)(42). Despite the efforts of the investigators, it must be acknowledged that the pupil’s answers could have been influenced by the questioner. Nonetheless, ergonomic furniture was deemed to be preferable for posture- particularly for reading and writing activities where the child leans back (38)(39)(42). Troussier et al. (42) reported 67% felt more comfortable in the ergonometric furniture but found no statistical significance between this comfort and the reduction in prevalence of back pain. Further research is required to investigate the magnitude of this effect on back pain.
Investigations into ergonometric chairs were furthered by Marschall et al. (40) and Niekerk et al. (41), where the effects were measured directly in the child’s posture. Marschall et al. (40) compared a traditional workstation (level desktop, 5° backward sloping seat) to an ergonomically designed workstation (15° sloping desktop, 15° forward sloping seat). EMG profiles of the latissimus dorsi, erector spinae and superior trapezius were conducted on 10 children (mean age of 4.7 years). Whilst no significant difference was found to the muscle activity of the erector spinae or superior trapezius, subjects demonstrated significantly less latissimus dorsi activity when seated at the ergonomic workstation (mean = 20·9 V ms) compared with the traditional workstation (mean = 24·4 V ms, t = − 2·88, p = 0·018). Given that tension in the posterior muscles is thought to be linked to the occurrence of back pain (5), it is promising that this ergonometric workstation could reduce pain prevalence. However, further research is needed to determine the efficacy of this. Niekerk et al. (41) also designed an ergonometric chair for experimentation, but this time with aim of enabling “dynamic sitting”. He proposed that this chair would enable more side flexion and pelvic rotation to reduce compressive forces through the spine. Research has shown that pelvic rotations whilst sitting have a positive impact on the vertebrae by varying load on the spinal structures, thus decreasing compressive forces on the discs (43). Niekerk et al. (41) found that there was a significant increase in the participant’s pelvic rotations in this chair compared to a regular classroom chair, although this was only represented in a sample of 11 results. However, Niekerk et al. (41) only tested on 13–18 year-olds, so the impact of this chair on younger students is still unknown. Despite promising results from both investigations, the common theme throughout is the use of small sample sizes. For a truly useful population-wide solution to be proposed, it must be shown as beneficial to children of all ages, proportions and measurements.
Sit-stand desks
Another potentially viable solution is “sit-stand desks”. The concept is that children will be more active and therefore put less stain through their developing spines if they stand in classrooms instead of sitting (44). The Ergotron (45) desks are a taller desk than normal, still with a regular stool behind; this design encourages more time spent standing and is a good example of the style investigated by the following authors. As described by Hinckson et al. (44), this is a cost-effective solution that could be made available around the world, particularly if the design entered the mass market. However, whilst it is predominately agreed that this style of desk increases children’s activity levels (10)(11)(46)(47)(48)(49), there is dispute over whether this actually makes any consequential change to the prevalence of back pain. Cardon et al. (47) studied two classrooms over 1.5 years; this study looked directly at the posture observed and self-reported discomfort. The findings were: the intervention group using the sit-stand desks spent more time in dynamic movement, but no differences in discomfort were reported from one group to the other. However, in two groups of 15 participants, Koskelo et al. (50) reported that over 2 years the self-reported pain in the upper back, neck and shoulder reduced significantly in the intervention group. It must be considered that this smaller sample size limits generalisability and further research is required to evaluate this potential solution that sit-stand desks present.
This review has implications for schools to consider with regards to the design and impact of classroom chairs. One resolution may be the introduction of ergonometric chairs- but there is cause for debate; Troussier et al. (42) found no impact of these chairs on the frequency of reported back pain. However, Troussier et al. (42) did not reflect on how individual children use the furniture differently. The “sit-stand desks” provide opportunity for greater levels of activity throughout the school day (47). Given physical activity was the main recommendation of the European Guidelines for Prevention of Low Back Pain (38) this freedom for movement is likely to be beneficial. With adulthood spinal pathologies rapidly increasing in prevalence, it has never been more important to research the prevention of these debilitating conditions and promote better posture in childhood.
Conclusion:
Currently, many school chairs and desks are designed such that the child will work with a 90° flexion of the hip joint, as is recommended to preserve lumbar lordosis (51). However, most will not fit the mold of the average pupil due the variation in children’s size and growth rate (52). Parcells et al. (53) reported that in a sample of 74 children less than 20% had access to acceptable chair/desk combinations for the anthropometrics of the child. Future research should focus on improving design in school furniture. Better school chairs could promote better posture and musculoskeletal health in school children; reducing the prevalence of back pain both in childhood and adulthood, and consequently the decreasing the resultant burden on public health care. It is my opinion that “sit-stand desks” could alleviate the many issues of poor posture discussed by increasing mobility in the spine.
References:
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