Muscle stiffness on both sides of the spine may be due to soft tissue injury, chronic muscle strain, rheumatic immune diseases and other reasons. 1. Soft tissue injury: when long-term in a movement, collision, sprain and other conditions lead to acute injury to the muscles and soft tissues next to the spine, there will be local pain, swelling and other symptoms, resulting in muscle stiffness. 2. Chronic muscle strain: long-term heavy physical labor and other factors can lead to chronic muscle injury such as lumbar muscle strain, lumbar muscle pain and stiffness can occur. 3. Rheumatic immune diseases: such as ankylosing spondylitis, which may result in spinal ankylosis, low back pain and stiffness of the lower back muscles. If you have the above symptoms or suspect soft tissue injury, chronic muscle strain, ankylosing spondylitis, etc., it is recommended that you go to the hospital in time to get a clear diagnosis and follow the doctor’s instructions for treatment.