Chest pain after sitting for a long time may be caused by pleurisy, costochondritis, intercostal neuritis, gastric disease, lung disease, heart disease and so on. 1. Pleurisy: If you suffer from pleurisy, the amount of chest water between the dirty pleura and the wall pleura gradually increases, resulting in stabbing or pulling pain in the chest, and the chest pain is more obvious after sitting for a long time. 2. Costochondritis and intercostal neuritis: if you suffer from costochondritis and intercostal neuritis, due to incorrect sitting posture, resulting in part of the intercostal tissues or joints for a long time uneven force, there will be a chest pain after sitting for a long time. 3. Stomach diseases: If you have stomach diseases such as stomach cramps and stomach ulcers, sitting for a long time will lead to the onset of the disease, which will cause chest pain. 4. Lung diseases: If lung diseases such as lung infection, tuberculosis and lung cancer are not under control, sitting for a long time will cause chest pain. 5. Heart disease: such as angina, coronary heart disease, heart attack and other heart diseases, sitting for a long time will lead to the onset of the disease, there will be chest pain symptoms. If you sit for a long time chest pain, it is recommended to go to the regular hospital as soon as possible to consult and examination, improve the appropriate blood tests, electrocardiogram, chest X-ray, cardiac CT, etc., a clear diagnosis, timely treatment of the cause of the disease. Normally, you should avoid sitting and standing for a long time, and you can exercise appropriately to relieve chest pain.