Human spine can exhibit three types of spinal deformity or curvature, namely: scoliosis, kyphosis and lordosis. These curvatures can lead to pain and discomfort of individual involved, disturbing productivity; and require expansive and prolonged treatment. One of the most common and costly problem in industrialized countries is related to low back pain (a musculoskeletal disorder affecting the lumbar spine). Many methods of measuring the spinal deformities have been investigated [1, 2, 3, 4]. Among various techniques, medical imaging techniques, including radiography and magnetic resonance imaging (MRI), are the most accurate methods; however, they are not yet well suited for recording the dynamic motion [5]. Actually, the quantitative assessment of lumbar spine kinematics is believed to be necessary for determining reference values in normal and pathological conditions leading to the best planning of surgical procedures and monitoring the progression and treatment of deformities [6, 7].Thus, motion capture (MoCap) measurement would be of value for clinical purposes [8, 9]. Therefore in this study, we aimed to elucidate two questions essential to the non-invasive assessment of spinal kinematics based on MoCap technique: (Q1) Does the external estimated curvature truly represent the internal deformity? (Q2) Is the use of lumbar curvature magnitudes sufficient to differentiate various postures performed during rehabilitation?