Running leg pain may be physiological pain caused by excessive running, or it may be caused by trauma, knee osteoarthritis, lumbar intervertebral disc herniation, and vascular diseases of the lower limbs. 1. Physiological pain: If long and strenuous running causes the accumulation of lactic acid inside the muscles, leg pain symptoms will appear, which is generally physiological and can be relieved after rest. 2. Trauma: If the legs are hit by impacts and other traumatic injuries during running, it can cause soft tissue injuries such as leg muscles and ligaments, or fractures, which can cause leg pain and swelling symptoms. 3. Knee arthritis: if there are knee degeneration, rheumatoid arthritis and other diseases, excessive running can lead to increased wear and tear of the knee joints, causing leg pain, which can be accompanied by limited activities, swelling and other symptoms. 4. Lumbar intervertebral disc herniation: when running, the lumbar intervertebral disc load increases, the intervertebral disc herniation aggravates, and the nerve root of the lower limb is aggravated by the compression, which may cause leg pain, numbness and other symptoms. 5. Lower extremity vascular diseases: such as lower extremity arteriosclerosis occlusive disease, lower extremity varicose veins and other vascular diseases, running can cause lower extremity ischemia aggravation, causing leg pain symptoms. Running leg pain may also be caused by many reasons, such as myofasciitis, etc., if the rest does not relieve, you should consult a doctor in a timely manner, improve the examination to clarify the cause of the disease, and comply with the doctor’s instructions for targeted treatment, so as not to delay the condition.