Correlation of prolonged sitting time and sitting posture on low back pain: A cross-sectional study among medical students at Universitas Sumatera Utara

Introduction

Low back pain (LBP) is the most prevalent musculoskeletal condition in the world, affecting 15–45% of people annually. Approximately 17.3 million individuals in the UK have suffered from low back pain, leaving 1.1 million immobilized. Additionally, it was reported that 26% of American adults complained about having low back discomfort at least one day every three months. According to National Basic Health Research of Indonesia (RISKESDAS) 2018, the prevalence of low back pain in Indonesia is expected to be between 7.6% and 37% and will continue to increase as people age.¹

Most cases of LBP have a multifactorial etiology.² The two most common factors associated with LBP complaints are extended periods spent sitting and improper posture.³ Up to 60% of adults report having low back pain because of sitting issues. Additionally, according to WHO, prolonged sitting can result in musculoskeletal issues, which can ultimately cause LBP.⁴

The risk of low back pain (LBP) can be elevated by prolonged sitting without a break. This is because sitting increases the pressure on the spine by two times, which can lead to an increase in biomechanical processes that can alter the form of the spine.⁵ According to Wibowo,⁶ an individual’s risk of low back pain (LBP) can be increased by 2.68 times by adopting an incorrect sitting posture, such as bending over, as opposed to sitting erect. The reason behind this is that a hunched sitting position can impose prolonged strain on the body’s muscles, making it an awkward and uncomfortable working posture.

Medical students are particularly vulnerable to LBP because of several risk factors, including stress, long study sessions, improper sitting postures, and insufficient physical activity.² Suffering from low back discomfort might hinder students’ performance and affect their education starting from the pre-clinical period and ultimately throughout their medical career.⁷

According to Amelot et al.,⁸ medical students usually study for more than seven hours every day. The rigorous lecture schedule forces students to sit still for extended periods, leading many of them to adopt incorrect sitting postures that increase their risk of developing musculoskeletal conditions like LBP.⁹ Medical students in Universitas Sumatera Utara (USU) engage in instructional activities on campus for roughly seven to nine hours per day. These kinds of activities include open lectures, tutorials (group discussions), laboratory practicums, and clinical skills labs that require students to sit longer. Moreover, most of them who frequently use computers in class while sitting with poor posture will also increase the likelihood of developing LBP.¹⁰

According to research by Vujcic et al.¹¹ in Belgrade (Serbia), the prevalence of medical students who experienced LBP was 59.5%. In France, the prevalence of LBP experienced by medical students was 72.1%.⁸ Meanwhile in Indonesia, the prevalence of research results conducted by Mutiara at Sriwijaya University among medical students regarding long relationships and sitting positions on LBP complaints was 59.4%.¹² However, research undertaken during the COVID-19 pandemic revealed that the frequency of LBP among medical students at USU was lower than other research, at 29,1%. Hasibuan claimed that a variety of factors, including the sitting position at home and the design of the chairs and tables used, affect the low prevalence which is difficult to evaluate in her research.¹³

Based on previous studies, a preliminary survey was conducted among twenty medical students at USU about LBP. Of the twenty students, it was discovered that eighteen of them complained of LBP anytime between or after lectures. Therefore, it is important to analyze whether there is a relationship between duration and sitting posture during lectures on LBP complaints among medical students at Universitas Sumatera Utara (USU).

Methods

Results

Discussion

With a prevalence of 59.9%, this study revealed that the majority of medical students at Universitas Sumatera Utara did not report having LBP problems. This is consistent with research done in 2021 by Hasibuan on USU FK students, where the majority of the sample (70.9%) did not experience LBP.¹³ However, there is a difference in the research conducted by Safitri in 2021 that the majority of medical students experienced LBP with a prevalence of 61.8%. The reason for this discrepancy is most likely that students with a BMI of ≥ 23 kg m⁻² were not excluded from Safitri’s research, which could have contributed confounding variables to the analysis.⁷ Research by Abdu et al.¹⁴ indicates that an individual who is overweight is more likely to get low back pain (LBP) because excess fat builds up in the abdominal region, which can weaken the abdominal muscles and tense the back muscles. Furthermore, the fact that women aged 20 years or younger made up most of the research sample may have contributed to disparities in prevalence. Therefore, there is still very little chance that LBP is the result of hormone imbalances. Studies conducted by Rasyidah et al.¹⁵ have shown that fluctuations in estrogen levels can affect LBP complaints in women with hormonal disorders, including those who are menopausal, pregnant, or use contraception.

Medical students at Universitas Sumatera Utara (USU) attend lectures from 7 a.m. to 4 p.m. on a demanding schedule. Students who attend dense lectures must remain still for extended periods, which might lead to LBP symptoms. It was discovered in this study that most students (72.1%) sat through lectures for more than seven hours a day. This is because apart from the busy lecture schedule, the percentage of attendance requirements for USU medical students is also high, such as 80% in general lectures and 100% in practicums, tutorials, and skills labs, where students need to sit down during these activities. Table 3 reveals that students who sat for more than seven hours per day had a higher percentage of LBP complaints (45.3%). The Chi-square analysis results indicate a significant correlation between sitting duration and LBP complaints, with a p-value of 0.041 (p < 0.05). The study’s findings are consistent with research by Eloi et al.² that shows that sitting for longer than seven hours a day can affect LBP complaints. Students who sit for longer than seven hours a day may experience worsening symptoms and functional changes in comparison to those who sit for less than seven hours, with a p-value of 0.02 (p < 0.05).

Long periods of sitting can affect LBP complaints because they induce continuous loading, which modifies the lumbar vertebral curvature.¹⁶ A packed lecture schedule in a matter of hours may worsen intra-discal vertebral compression, which in turn may cause back pain.¹⁴ In addition, prolonged sitting can strain the muscles and ligaments in the back, particularly the posterior longitudinal ligament, which is the thinnest ligament in the L2-L5 region and is linked to low back pain.¹³ Extended periods of static muscle contractions can impair blood flow to the muscles, which can lead to fatty acid buildup as a result of impaired glucose metabolism. This procedure may result in discomfort including exhaustion and lower back pain, which may affect an individual’s productivity at work.^14,17

Besides the amount of time spent sitting, sitting posture can also affect lower back pain (LBP) problems. At 66.7%, the majority of USU FK students in the class of 2021 had decent sitting posture. This may be a result of the student’s prior knowledge of the correct sitting technique, which was covered in the dermato-musculoskeletal lecture during the previous semester. According to Table 4, which examines the association between sitting posture and LBP complaints, students who have bad sitting posture are more likely to report having LBP, at a prevalence of 55.1%, than students who have good sitting posture, at 32.7%. Chi-square analysis in this study found a significant relationship between sitting posture during lectures and complaints of LBP with a p-value of 0.009 (p < 0.05). These results are in line with Desenia’s research in 2023 which stated that poor sitting posture can cause pain due to less physiological conditions in the vertebrae with the p-value obtained being 0.0001 (p < 0.05).¹⁸

The chance of developing LBP can be raised by bad sitting posture. Based on Table 5, the multivariate analysis’s findings indicated that students who sat poorly were 2.438 times more likely to have low back pain (LBP). The present findings are consistent with the study carried out by Abdu et al.,¹⁴ which found that sitting position had the highest risk of producing lower back pain (LBP) among the three variables examined. An improper sitting posture can result in spasms and excessive straining of the ligaments and muscles surrounding the spine, which can lead to lower back pain (LBP).¹⁸ LBP is more likely to develop in students who frequently sit with their backs tilted forward, cross their legs, or are hunched over. This is because sitting in these postures can produce discomfort by applying pressure to the spinal cord and soft tissues.¹⁵ According to research by Wijayanti et al.¹⁹ pain occurs more often in bent and upright sitting postures. An upright sitting posture can increase the pressure on the nerve bed by 140%, meanwhile sitting bent over can cause an increase in pressure by 190%.²⁰ Apart from that, disorders can also occur in the erector spine muscles in the form of tension due to excessive contraction.^19,21 Sitting hunched over can also increase the risk of a herniated nucleus pulposus (HNP). LBP patients may experience pain that radiates to the affected spinal nerve segment when their spinal nerves are squeezed as a result of an intervertebral disc rupture brought on by elevated pressure from an improper sitting position.²² People who cross their legs while sitting can experience asymmetry in the left and right sides of the body, as well as increased rotation of the pelvic and lumbar spine. This can cause the hip joints to flex, which increases the chance of developing scoliosis or other spinal deformities.²³

LBP issues may also be influenced by the way tables and chairs are used and designed. According to Abdul et al.¹⁴ The presence of armrests and seat cushions may have an impact on the chair’s seat and backrest angles. A 92 cm high table and a chair with suitable foot support are the best settings for studying, according to research by Sambo.¹⁶ In order to prevent weariness and soreness, the chair’s backrest is also helpful in holding and supporting the back region. This is because when you sit on your back, the weight of your body is concentrated on your spine, which reduces joint tension and promotes greater muscle and tendon relaxation.²⁰

According to research by Hadi and Hasmar,²⁰ several factors need to be considered when sitting to prevent lower back pain (LBP). It is recommended that you sit with your buttocks touching the chair and your shoulders resting against the backrest. Your legs shouldn’t be crossed, and your knees should be maintained by bending at the proper angle at or below your hips. Elbows and arms can be rested on the support of a chair or table and you need to keep your shoulders relaxed. Avoid sitting in the same posture for more than 30 minutes and do not sit in a hunched iposture. If the chair does not have lumbar support, try to keep the back in a curved lumbar curve.