A Cross-sectional Study on Association of Iliopsoas Muscle Length with Lumbar Lordosis Among Desk Job Workers

Abstract

Background:

Prolonged hours of sitting in sustained posture is a common job requirement of desk job workers. Potential risk of iliopsoas muscle shortening leading to lumbar hyperlordosis, which in turn may cause low-back pain was identified. Thus, this study determined association between iliopsoas muscle length and lumbar lordosis in desk job workers.

Methods and Material:

This cross-sectional study was conducted on forty-six desk job workers working for 5 hrs/day for at least 5 years. Workers were assessed for iliopsoas muscle length using Modified Thomas test and flexi-ruler was used to measure lumbar lordosis. Pearson’s correlation was operated for association of iliopsoas length with lumbar lordosis.

Results:

Lumbar lordosis demonstrated moderate positive correlation with both right (r = 0.628) and left Iliopsoas muscle length (r = 0.647).

Conclusion:

This study concluded workers with higher degree of lumbar lordosis presented with shorter iliopsoas length. Timely intervention to maintain the length of this muscle will ensure low incidence of low-back pain among desk job workers thereby safeguarding their spine due to cumulative trauma.

INTRODUCTION

Low-back pain (LBP) has a high prevalence among desk job workers and is one of the most common cause of work-related disability in people under the age of 45.[1] Kashmeera et al.[2] define work-related musculoskeletal disorders (WRMSDs) as “impairments of bodily structures such as muscles, nerves, tendons, joints, cartilage and spinal discs that are caused or aggravated primarily by the performance of work and by the effects of immediate environment where work is carried out.”

Desk job workers adopting sustained sitting posture throughout the day are known to be prone to adaptive changes in the musculoskeletal system that can potentially shorten the length of skeletal muscles. It is known that prolonged sitting causes increased anterior pelvic tilting due to shortening of hip flexor musculature primarily the iliopsoas muscle.[3] As per length-tension relationship, a short/tight length of muscle is directly proportional to increased risk of injury or cumulative trauma. Iliopsoas tightness resulting in anterior pelvic tilt coupled with lumbar hyperlordosis is reported as one of the common aetiology of mechanical low-back pain. High prevalence (38%) of WRMSDs among desk job workers confirm this postulation/hypothesis.[4]

Sedentary lifestyle is a currently a leading risk factor across the spectrum of noncommunicable diseases, which can potentially lower the quality of life.[5,6] With a rise in the number of companies offering remote working and work from home options involving routine sitting posture, it is deemed essential to understand and evaluate flexibility of iliopsoas muscle thereby contributing in designing safe workstation exercise protocols. Hence, this study aims to correlate length of iliopsoas muscle length with lumbar lordosis among desk job workers.

METHODOLOGY

Forty-six desk job workers (Mean-age: 39.11 ± 6.81) were recruited in this cross-sectional study using convenience sampling. Study commenced after approval from the Institutional Ethics Committee. Informed consent was sought. The confidentiality of participants was always maintained during the course of study. Hybrid workers and people with any history of congenital deformity of lower limb, major surgeries, recent musculoskeletal injuries, or any soft tissue injuries in lower limb or low back in past 6 months were excluded. Data on demographic characteristics were documented.

Procedure

Iliopsoas muscle length was evaluated using Modified Thomas test. The participants were instructed to sit at the edge of plinth and asked to roll back while pulling both knees to the chest to posteriorly. Participant was then directed to hold the opposite hip in maximum flexion with arms, whereas limb to be tested was lowered in direction of floor to ensure that lower limb to be tested hung freely over edge of the plinth. A 5 degree or more extension deficit at the hip joint attributable to the iliopsoas was used as a criterion for determining shortening of the iliopsoas muscle.[7,8]

For measurement of lumbar lordosis, participants were asked to comfortably stand in symmetrical weight-bearing position and fix their gaze on the opposite wall. Spinous process of T12 was marked as a point where lumbar curvature began and the spinous process of S2 was marked as endpoint of curvature. Examiner carefully molded flexible ruler to midline contour of participant’s lumbar spine. Contour of lumbar spine obtained from flexible curve was carefully traced onto paper. Lumbar lordosis was calculated with following equation: β =4 Arctang2H/L. A vertical line was drawn to connect the T12 and S2 landmarks (total length of curvature/L line). First, maximum width (deepest part of curvature/H line) and then middle of the lumbar curvature length (midpoint of curvature/H line) were measured in centimeters and used to [Figure 1] calculate the lumbar lordosis using the related equation.[9]

Figure 1.

Assessment of iliopsoas muscle length

Recorded data was transferred to Microsoft Excel (USA, version 20.0). For association of iliopsoas length with lumbar lordosis, data were passed through check of normal distribution, and Pearson’s correlation was operated as data was normally distributed.

RESULTS

It was noted that participants between the age group of 30-34 years comprised of majority of study population (30.43%) with a mean age (years) of 39.11 ± 6.81. Female participants showed higher participation (59%). Majority of participants (30%) reported sitting for 8 hours/day and 33% reported 48 hours of sitting per week. Shapiro-Wilk test was operated for determining normal distribution of lumbar lordosis (degree) and iliopsoas muscle length among desk job workers. It was noted that all three outcome parameters followed the criteria for normality; viz; lumbar lordosis (P = 0.119); left iliopsoas length (P = 0.723) and right iliopsoas length (P = 0.262).

A moderate positive correlation was noted between both lumbar lordosis and right iliopsoas length (r = 0.62, P = 0.00*). Figure 2 and left iliopsoas length (r = 0.64, P = 0.00*) [Figure 3].

Figure 2.

Correlation between lumbar lordosis and right iliopsoas muscle length

Figure 3.

Correlation between lumbar lordosis and left iliopsoas muscle length

DISCUSSION

Participants included in this study were 46 desk job workers, out of which 97.8% participants presented with iliopsoas muscle tightness. Length of right iliopsoas (11.46 deg ± 4.59) was marginally less than the length of left iliopsoas (11.54° ± 4.41) [Table 1]. Average degree of lumbar lordosis was 23.32° ± 8.00 among participants.

Table 1.

Summary of correlation analysis

Correlation analysis	Ilio-psoas length (deg) Mean±SD	Lumbar lordosis (deg) Mean±SD	Correlation coefficient (r)
Right	11.46±4.59	23.32±8.00	0.63
Left	11.54±4.41	23.32±8.00	0.65

It is known that the iliopsoas muscle originates from fusion of the psoas major and iliacus muscles. Fusion occurs at L5-S2 level and inserts into the lesser trochanter of the femur.[10] Iliopsoas is a primary hip flexor, and it has the potential to influence, and be influenced by, movements at both the spine and the hip joints. Being a postural muscle, iliopsoas has an inherent tendency to undergo shortening in response to excessive stress or cumulative trauma.[11,12] Williams attributed low-back pain to increased lumbar lordosis resulting from abdominal muscle weakness because of prolonged sitting posture.[13]

There was a moderate positive correlation between right and left iliopsoas muscle length with lumbar lordosis (Right: r = 0.63, P < 0.05), (Left: r = 0.65, P < 0.05). Findings of the study by Guidotti, T.L. et al., and cote concluded positive correlation between hamstring and iliopsoas tightness with low-back pain.[14,15] They suggested adaptive shortening associated with prolonged sitting jobs as a probable cause for this finding. The results of this study corroborate with this study that identified positive correlation between iliopsoas muscle tightness and lumbar lordosis. In a study by Jorgensson A, relationship between iliopsoas muscle length and the lumbar lordosis was examined using the Pearson product-moment correlation.[8] A correlation between iliopsoas muscle tightness and increase in degree of lumbar lordosis (r = 0.4033, P = 0.001) was identified. Another study by Hellsing et al. (1987)[7] concluded marked shortening of iliopsoas muscle in approximately 80% of study population whereas Barber et al.[16] determined iliopsoas tightness in only 35% of their cohort. This difference could be attributed to the lower age group of students recruited in the later study. Pradip B, Sudhir B, and Nidhi B concluded that most Indian desk job professionals, in their middle age with a longer work history developed tightness of iliopsoas muscle thereby increasing the risk of low-back pain.[17]

In addition, work from home culture leads to workers spending longer hours at their desks in the absence of commuting, limited traveling, and increased use of computers to conduct meetings rather than holding face-to-face meetings at various physical locations.[18,19] Sustained sitting in office workers’ personal as well as in their professional lives all tend to contribute to sedentary lifestyle and is a significant risk factor for lower quality of life.

Therefore, early detection of possible muscle imbalances responsible for causing low-back pain will be important strategy for preventing spine disability in desk job workers. One such muscle contributing to this imbalance is the iliopsoas muscle. Hence, it was deemed essential to evaluate iliopsoas muscle tightness among desk job workers to prevent work-related musculoskeletal disorders.

CONCLUSION

This study provides prefatory support for prevalence of iliopsoas muscle tightness among desk job workers. Findings of the study suggested that there is moderate positive correlation between iliopsoas length and lumbar lordosis in desk job workers implying that the participants with higher degree of lumbar lordosis presented with increase in iliopsoas muscle tightness. Thus, timely prevention strategies including work-station exercises planned at reducing the iliopsoas tightness will aid in decreasing the risk of developing work-related low-back pain among desk job workers. Longitudinal follow-up to understand the prevalence of low-back pain among participants with high iliopsoas tightness will further warrant present findings.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.