Lumbar mobility and strength correlate with low back pain and quality of life

Background Spinal mobility and functional strength is an integral part in the orthopaedic and rheumatologic assessment of patients with spinal disorders and chronic low back pain (cLBP), yet their relationship with health-related quality of life (QoL) remains insufficiently explored. Patients and methods This is a retrospective cross-sectional study that recruited volunteers with (cLBP) and without chronic low back pain (nLBP) between 2022 and 2025. Lumbar mobility was assessed using a device-assisted back-scan (Idiag M360 ® ), as well as conventional functional assessments, including Schober and finger-to-floor-distance (FFD). Functional strength was assessed via sit-to-stand test (STS). Primary outcomes were the short form 36 domains Physical Functioning (SF36-PF) and Bodily Pain (SF36-BP) as well as cLBP. The International Physical Activity Questionnaire–Short Form (IPAQ-SF) served as a secondary outcome measure. Multivariable linear regression models were performed adjusted for baseline characteristics; and in a subgroup analysis stratified by LBP; binary logistic regression was performed to evaluate the independent associations of each measure for cLBP. Results 1,309 adults (cLBP = 562, nLBP = 747) were included. LBP groups were comparable in BMI and physical activity. The STS, FFD and Idiag M360 thoracolumbar flexion/extension were significantly associated with SF36-PF and SF36-BP in both pain-status groups (all p ≤ 0.002). Greater STS performance, higher (inverted) FFD and Idiag M360 thoracolumbar flexion/extension were associated with a lower OR of cLBP (all p ≤ 0.001). The Schober test showed weaker associations with SF-36 overall (β* = 0.085–0.120). The IPAQ showed no meaningful associations with any mobility measure. Conclusions Lumbar functional strength and mobility were strongly associated with cLBP and QoL and when reduced, was associated with higher odds for cLBP. The findings of this study support the adoption of STS and device-assisted mobility measurements for functional assessment of the spine; whether these measures can identify early, modifiable determinants of QoL or predict outcomes remains a hypothesis for prospective studies.