Sore legs without pain on the second day of closed needle treatment may be due to side effects of the medication. However, sore legs without pain can also be caused by cold, lack of calcium and other reasons. 1. Side effects of medication: Sore legs may occur after the injection of closed needle, which is a side effect of medication and usually disappears after a few days. 2. Cold: After getting cold, the soft tissues around the knee will be tense, and the metabolites such as lactic acid will increase, which will easily cause leg soreness when it stimulates the peripheral nerves. 3. Calcium deficiency: prolonged insufficient calcium intake or excessive calcium loss can lead to osteoporosis, which can also cause symptoms of leg soreness. After the closed needle, you should pay attention to the wound to avoid touching water, avoid strenuous exercise. Maintain local hygiene. If the symptoms are serious or persistent soreness, you should go to the hospital in time, under the guidance of the doctor targeted treatment.