If calf cramps occur while running, there are several factors as follows: 1. The most common factor is ionic disorder, when there is excessive running, there will be a lot of sweating. The body will lose body fluids when sweating, along with the loss of body fluids and a variety of ions in the body, such as the body lost excessive calcium ions and potassium ions, there will be running calf cramps. 2, patients with primary hypocalcemia, if the amount of exercise increases, will also cause secondary hypocalcemic convulsions. 3, such as tendons, ligaments and joint diseases, will also appear when running calf cramps. 4, if there is no sufficient warm-up and sufficient activity before running, suddenly running, calf will also be because of the sudden increase in muscle explosive force, and lead to the reaction of transient cramps.