When the patient has the symptom of swelling and hardness of calves while sitting, it may be caused by physiological factors, and also may be caused by varicose veins, muscle spasm and other diseases. 1. Physiological factors: the patient may have poor blood circulation in the veins of the calf due to improper sitting posture, which causes swelling and hardness of the calf while sitting. 2. Varicose veins: When the patient suffers from varicose veins, the blood return to the veins of the calf is blocked and the blood is stagnant, which causes swelling and hardening of the calf. 3. Muscle spasms: When patients suffer from muscle spasms, the calf muscles will spontaneously contract, resulting in the calf muscles straightening, which causes sitting calf swelling and hardness. When the patient appears sitting calf muscle swelling hard symptoms, it is recommended that the patient timely medical care, clear cause, follow the doctor’s instructions standardized treatment.