Males and females with chronic low back pain display consistent differences in lumbar spine alignment during clinical tests and a functional task

154 people with chronic low back pain (CLBP) were recruited for a baseline data collection, as a part of a randomized, controlled clinical trial. All participants completed the Numeric Pain Rating Scale (NRS), modified Oswestry Disability Questionnaire (MODQ), clinical tests of maximum flexed and extended sitting and a functional task of preferred sitting. 3D motion capture was used to calculate the lumbar spine curvature angle (LCA; index of lumbar spine alignment) for each test. Males and females were similar in NRS and MODQ. LCAs were different across the three tests, and males and females consistently displayed different LCAs. Females had a greater LCA (i.e., more extension) for all tests. Therefore, clinicians who evaluate people with LBP conditions should consider the effects of gender on lumbar spine alignment. Furthermore, gender-related differences observed during clinical tests are also present during a functional task of preferred sitting.