Lumbar paraspinal muscle quality and disability in older adults: insights from the SarcoSpine cohort

BACKGROUND: Lumbar paraspinal muscles (LPMs) are essential for spinal stability, movement, and daily activity. This study aimed to investigate the association between LPM quality and patient-reported disability in community-dwelling older adults. METHODS: This study included 111 participants aged ≥ 65 years from the SarcoSpine study, a prospective observational cohort. Magnetic resonance imaging (MRI) was utilized to quantify LPM quality via signal intensity and LPM quantity via muscle volume normalized by height squared (volume/Ht2). Disability was evaluated using the Oswestry Disability Index (ODI), and physical performance was assessed through various standardized tests. Multivariate regression analyses were conducted, adjusting for age, sex, and low back pain intensity. RESULTS: A total of 111 community-dwelling older adults (mean age 70.6 ± 4.2 years; 63% women) were analyzed. The mean ODI score was 9.14 ± 7.76%, indicating minimal disability, and physical-performance measures reflected high functional capacity (mean SPPB 11.56, TUG 8.57 s). LPM quality was significantly associated with ODI scores (R2 = 0.648, p < 0.001) after adjusting for covariates, while LPM quantity was not (p = 0.331). CONCLUSIONS: LPM quality, rather than quantity, was associated with disability levels among community-dwelling older adults. These findings suggest that maintaining better muscle composition and reducing fat infiltration may be linked to lower functional decline and improved quality of life in aging populations.