Relationship between mechanical factors and incidence of low back pain

PainSci » bibliography » Nourbakhsh et al 2002
updated Feb 7, 2023

Tags: etiology, back pain, structuralism, pro, pain problems, spine, biomechanical vulnerability

Two pages on PainSci cite Nourbakhsh 2002: 1. The Complete Guide to Low Back Pain 2. Psoas, So What?

PainSci notes on Nourbakhsh 2002:

The key findings:

“It appears that muscle endurance and weakness are associated with LBP and that structural factors such as the size of the lumbar lordosis, pelvic tilt, leg length discrepancy, and the length of abdominal, hamstring, and iliopsoas muscles are not associated with the occurrence of LBP.”

Nourbakhs and Arab did indeed identify a correlation between cLBP and pain and poor muscle endurance and strength, but correlation is (famously) not causation. They did not establish that the relationship is causal, or that improving these metrics is therapeutic, so note that their data is not very useful for supporting the value of core training as an intervention for back pain. And so, despite finding weak back muscles in back pain patients, it cannot by itself support the value of core training (meanwhile, there's a bunch of other more relevant and recent evidence to consider).

What I think is most significant in their results is that they found not even a correlation between chronic low back pain and various “structural” features. And where there is not even a correlation, there cannot be causation! So this data is useful for supporting the point that structure doesn’t seem to have much to do with back pain.

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

STUDY DESIGN: A multifactorial cross-sectional nonexperimental design.

OBJECTIVES: To collectively investigate the association among 17 mechanical factors and occurrence of low back pain (LBP).

BACKGROUND: Several physical characteristics, based on assumptions, clinical findings, and scientific experiments, have been associated with the development of LBP Controversy exists regarding the degree of association between some of these physical characteristics and LBP. Information regarding the degree of association of each factor to LBP is needed for effective prevention and appropriate treatment strategies.

METHODS AND MEASURES: A total of 600 subjects participated in this study. Subjects were categorized into 4 groups: asymptomatic men (n = 150, age [mean +/- SD] = 43 +/- 15 years), asymptomatic women (n = 150, age [mean +/- SD] = 43 +/- 13 years), men with LBP (n = 150, age [mean +/- SD] = 43 +/- 14 years), and women with LBP (n = 150, age [mean +/- SD] = 43 +/- 13 years). Seventeen physical characteristics were measured in each group and the relative association of each characteristic with LBP was assessed.

RESULTS: Among all the factors tested, endurance of the back extensor muscles had the highest association with LBP Other factors such as the length of the back extensor muscles, and the strength of the hip flexor, hip adductor, and abdominal muscles also had a significant association with LBP.

CONCLUSION: It appears that muscle endurance and weakness are associated with LBP and that structural factors such as the size of the lumbar lordosis, pelvic tilt, leg length discrepancy, and the length of abdominal, hamstring, and iliopsoas muscles are not associated with the occurrence of LBP.

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

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