Objective To investigate how often changes in an individual's volitional spinal movement related to changes in low back pain and activity limitation in studies that accommodated individual heterogeneity. Design Etiology systematic review. Literature Search MEDLINE, Embase, CINAHL, and AMED were searched from inception to January 2020. Study Selection Criteria This study included peer-reviewed single-case design (including case series) articles that reported objectively measured volitional spinal movement and low back pain or activity limitation, before and after nonsurgical or nonpharmacological intervention. Data Synthesis We summarized the frequency with which changes in movement related to changes in pain or activity limitation. For each relationship found, we synthesized the type of movement change that related to improved pain or activity limitation. Results Twenty-three suitable studies (n = 33 participants) of low overall quality were identified. A relationship between changes in movement and changes in pain or activity limitation was identified 72% of the time (57.5 of the 80 times investigated). In the presence of a relationship, improved pain or activity limitation was consistently (55.65 of the 57.5 relationships, 97%) related to increased spinal movement range, velocity, or flexion-relaxation (reduced muscle activity at full flexion). Conclusion Among study designs that can accommodate the heterogeneity of low back pain by individualizing the intervention and the assessment of movement, a relationship between changes in movement and changes in pain or activity limitation was frequently observed. JOSPT Cases 2021;1(4):199–219. doi:10.2519/josptcases.2021.10231