The most common causes of sore legs are over-exercise, muscle spasm, lumbar disc herniation, etc. The most common causes are over-exercise, muscle spasm, and lumbar disc herniation. 1. Excessive exercise: once the patient has performed a long time, high intensity exercise, and did not carry out relaxation training in time after the exercise, it is easy to cause lactic acid accumulation in the legs, and when the lactic acid metabolism can be caused by the leg soreness and lack of energy. 2. Muscle spasm: if the surrounding environment temperature is too low, the patient’s legs are stimulated by cold, it is easy to cause muscle spasm, which in turn induces the leg soreness and weakness, you can pay attention to the warmth of the legs. 3. Lumbar disc herniation: If the patient has a lumbar disc herniation, the herniated lumbar disc compresses the surrounding soft tissues and nerves, which will easily cause the lower limbs to become sore and weak. Causes of leg soreness and weakness are more reasons, may also be related to trauma, deep vein thrombosis of the lower extremities, hypokalemia and other factors, if the symptoms continue to have no relief, it is recommended to go to the hospital in time to find out the cause of the disease, and targeted treatment by the doctor.