Pain in the middle of the undershirt is considered to be related to degenerative spinal lesions, fasciitis, ankylosing spondylitis and other causes. 1. Degenerative spinal lesions: With age, degenerative spinal lesions, herniated intervertebral discs, osteophytes and other changes can cause pain in the middle of the undershirt if they cause pressure on the surrounding tissues. 2. Fasciitis: Fasciitis is related to strain, trauma, cold and damp stimulation, etc. These factors will cause aseptic inflammation of the fascia of the back, which will lead to back pain, stiffness and other symptoms. 3. Ankylosing spondylitis: Ankylosing spondylitis is an autoimmune disease that affects the spine as well as other tissues, and under the stimulation of chronic inflammation, it can also cause pain in the middle of the back. There are other causes of pain in the middle of the undershirt, such as trauma, osteoporosis, etc. You should go to the hospital to find out the cause of the disease and then target treatment.