Relationship between mechanical factors and incidence of low back pain.
METHODS
A multifactorial cross-sectional nonexperimental design.


OBJECTIVE
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
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.


CONCLUSIONS
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.
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007870:Leg Length Inequality / Q000503:physiopathology; D016015:Logistic Models; D008141:Lordosis / Q000503:physiopathology; D017116:Low Back Pain / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000502:physiology; D010807:Physical Endurance