Relationship Between Hip Extensor Strength and Back Extensor Length in Patients With Low Back Pain: A Cross-Sectional Study

The purpose of this study was to examine the relationship between hip extensor strength and back extensor length in patients with low back pain (LBP) and healthy controls.

In 266 patients with LBP and 215 matched controls, back extensor length and hip extensor strength were measured and compared in the 2 groups using an independent t test. The Pearson correlation coefficient was used to determine correlation between these 2 variables. Multivariate logistic regression was used to test the risk of sustaining LBP with having these muscle insufficiencies.

A significant difference in hip extensor strength was found between patients with LBP and controls (P < .001). Back extensor length was different in healthy men compared with the patients with LBP (P < .001) but was not significant between women with and without LBP (P = .34). The results showed a significant relationship between back extensor length and hip extensor strength in men with LBP (r = 0.6, P = .01). Multivariate logistic regression revealed that having a weak hip extensor (P = .001) or shortened back extensor (P = .01) could increase the risk of LBP occurrence.

The findings support the assumptions of the presence of muscle imbalance of hip extensor weakness and back extensor tightness in male patients with LBP and that each muscle impairment may contribute to LBP.