Hiyama A, et al. - Through a retrospectively evaluated 140 patients who were hospitalized for surgery to treat lumbar spinal stenosis (LSS) and/or degenerative spondylolisthesis (DS), the researchers explained the role of the multifidus (MF) and psoas major (PS) muscles in maintaining global spinal alignment in patients with LSS and/or DS, and to investigate whether each muscles’ cross-sectional area (CSA) associated with whole-body skeletal muscle mass (SMM) using bioimpedance analysis. At L4-L5, the average PS CSA (AveCSA) was the highest while at L5-S1MF AveCSA was highest. In men vs women, paraspinal muscle CSAs were greater. For either MF or PS, no statistically important variation between the left and right CSA was found. The correlation coefficient exhibited strong associations among the PS AveCSA (L4-L5) and whole-body SMM. A weak association between SMM and PT was also discovered. Moreover, PS AveCSA (L4-L5) related to the PT and age, while PT associated with the whole body SMM but not with age. In conclusion, among the spinal parameters, whole-body SMM exhibited a relationship with PS AvCSA (L4-L5) and with PT which was the comparable outcome in MF AvCSA (L4-L5). Further, the posterior inclination of the pelvis may be associated with paraspinal muscle area instead of the age.