There are several reasons for soreness on both sides of the lower back: 1. The most common reason is strain, which generally leads to muscle strain in the lower back after maintaining a certain posture for a long time, and patients will have obvious soreness in the lower back, and positive signs cannot be found through various hospital examinations, which can be relieved by rest and posture adjustment. 2. It may be related to internal diseases, such as patients with cholecystitis or gallstones. 3. if there is heart disease, such as angina pectoris, coronary heart disease, etc., the patient will often show pain on the left side of the back. 4. may be related to anger, etc., if a person is angry, it will lead to the phenomenon of qi stagnation and blood stasis in the chest, which will manifest as soreness on both sides of the back.