Sore legs after sex may be caused by leg muscle tension, or it may be caused by lumbar spinal stenosis, varicose veins and other diseases. 1. Tension in leg muscles: if the patient has a long sex life, or if the patient has a strenuous sex life, the muscles will be in a tense state due to excessive exercise, and the muscles will metabolize more lactic acid, which will stimulate the patient’s leg muscles, and the phenomenon of leg soreness will occur after sex. 2. Lumbar spinal stenosis: Lumbar spinal stenosis is mainly caused by congenital spinal dysplasia or acquired factors. The main symptoms of patients are lower limb pain, low back pain, sciatica, etc. Lumbar spinal stenosis can also lead to cauda equina syndrome. 3. Varicose veins: The etiology and pathogenesis of varicose veins are still unclear, and it is considered to be caused by a variety of factors such as increased venous pressure due to congenital dysplasia of vein walls. Patients will have symptoms such as lower extremity pain, discomfort, hyperpigmentation, edema, etc. Varicose veins can also cause male patients to have symptoms such as increased scrotal volume, accompanied by a feeling of swelling, hidden pain and so on. When patients experience symptoms after sex, it may be a normal physiological phenomenon caused by leg muscle tension and does not require treatment. If it is caused by a disease, patients should seek medical treatment in time and follow the doctor’s instructions.