The most common reasons for not being able to stand up straight are over-exercise, soft tissue injury, lumbar disc herniation, lumbar spondylolysis, ankylosing spondylitis, etc. If the symptoms persist, it is recommended to consult a doctor in time. 1. Excessive exercise: If the patient is engaged in strenuous sports, it is easy to cause the accumulation of lactic acid in the lumbar back muscles, which in turn produces pain, and the patient may not be able to straighten his back, which is usually relieved after resting. 2. Soft tissue injury: patients with lumbar trauma, resulting in muscle, ligament, bone damage, or lumbar muscle strain, lumbar muscle strain, may not be able to straighten the waist performance. 3. Lumbar disc herniation: the lumbar disc will degenerate with age, and the protruding lumbar disc compresses the nerve root, which causes pain in the lower back and can’t straighten up. 4. Lumbar spondylolisthesis: If the upper and lower vertebrae of the lumbar spine slip, serious patients may develop lumbar spinal stenosis, accompanied by pain and numbness in the lower limbs, and patients are usually unable to straighten their backs. 5. Ankylosing spondylitis: patients with ankylosing spondylitis will involve the sacroiliac joints, lumbar region, etc. When the inflammation is in acute attack, the patient may experience severe discomfort, and then can’t straighten up the waist. Caused by the inability to straighten the waist of more reasons, but also may be related to the lumbar spine small joint disorders, rheumatoid arthritis, lumbar dorsal myofasciitis and other diseases, if sufficient rest did not relieve, it is recommended to timely go to the hospital for examination, by the doctor targeted for treatment.