Answer:
oxygen.
When a person runs, the demand for oxygen in the body increases, including in the heart muscle. If the artery is partially blocked, it may not be able to provide enough oxygen to the heart muscle, leading to chest pains. This is known as angina. It is important to see a doctor if you experience chest pains, especially during physical activity, as it may be a sign of a more serious condition such as coronary artery disease.