Muscle pain on both sides of the waist may be caused by strenuous exercise, lumbar muscle strain, lumbar intervertebral disc herniation and other reasons. 1. Strenuous exercise: If you do not exercise for a long time, the recent sudden and prolonged exercise, such as running, sit-ups, etc., can cause the accumulation of lactic acid in the muscles, and these products can not be removed in time, then it can cause the phenomenon of muscle pain on both sides of the waist. 2. Lumbar muscle strain: prolonged sedentary, laborious work and other reasons for lumbar muscle fatigue, resulting in lumbar muscles, fascia and ligaments sustained tension, increased intramuscular pressure, impeded blood supply, triggering inflammation, adhesion and other phenomena, lumbar muscles can be accompanied by pain. 3. Lumbar intervertebral disc herniation: it may be caused by degeneration of lumbar intervertebral disc and long-term physical labor. The fibrous ring of the lumbar vertebrae may rupture, and the nucleus pulposus may protrude (or prolapse) from the ruptured place in the back or the spinal canal, resulting in stimulation or compression of the adjacent spinal nerve roots, which may cause pain in the muscles on both sides of the waist. There are many causes of muscle pain on both sides of the waist, and it is recommended that patients go to the hospital in a timely manner and follow the doctor’s instructions for treatment to avoid delays.