[Purpose] The aims of this study were to examine the relationship between range of motion/muscle strength of the spine and lower limbs with 1) radiographic sagittal alignment and 2) quality of life of participants with spinal deformities to adequately target the appropriate factors for effective treatment. [Participants and Methods] This study used an observational cross-sectional correlational design. Participants with spinal deformities and low back pain were recruited for the study. The dependent variables were range of motion/muscle strength of the spine and lower limbs, sagittal alignment, and quality of life. [Results] Regarding alignment, significant correlations were found between hip extension range of motion and sagittal vertebral axis; between occiput-to-wall distance and thoracolumbar kyphosis; and between back extensor endurance and pelvic tilt and pelvic incidence-lumbar lordosis mismatch, also known as the calculated (pelvic incidence) minus (lumbar lordosis) value. With regards to quality of life, significant correlations were found between pain-related disorders and lumbar spine range of motion, and between gait disturbance and knee and hip extension ranges of motion. [Conclusion] Our findings suggest that these factors should be targeted for assessment and treatment of adults with spinal deformities.