Can a VR headset accurately measure how well you move with back pain?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age 18 to 55 years. * Clinician-diagnosed chronic non-specific low back pain (pain duration ≥ 3 months). * Applied to Selcuk University Medical Faculty Physical Therapy and Rehabilitation outpatient clinic with low back pain complaint. * Able to walk independently and safely perform the Timed Up and Go (TUG) and VR-TUG tests (with or without usual assistive device). * Able to understand and follow instructions; literate in Turkish (at least primary school education). * Willing to participate and able to provide written informed consent. Exclusion Criteria: * Red flag conditions or suspected specific pathology (e.g., fracture, tumor/metastasis, infection such as spondylitis/discitis). * Inflammatory back pain suggestive of conditions such as ankylosing spondylitis or sacroiliitis. * Significant radiculopathy or neurological deficit (dermatomal leg pain, marked weakness, reflex changes, sensory loss), clinically significant lumbar disc herniation, severe spinal stenosis, or spondylolisthesis grade II or higher. * Prior lumbar spine surgery. * Lower-extremity conditions that substantially limit mobility (e.g., severe hip/knee osteoarthritis, hip/knee arthroplasty, amputation, severe deformity). * Neurological disorders affecting gait or balance (e.g., stroke, Parkinson's disease, multiple sclerosis, progressive neuromuscular disease). * Vestibular disorder or recurrent severe vertigo affecting balance. * Severe cardiac or pulmonary disease that may compromise safety during testing. * Pregnancy. * Contraindications to VR use (e.g., photosensitive epilepsy) or history of severe VR intolerance (significant nausea, dizziness, visual discomfort, or migraine triggered by VR). * Severe cognitive impairment, major psychiatric disorder, or communication problems preventing cooperation. * Severe visual or hearing impairment that prevents following instructions or safely using VR.