The most common causes of foot and leg cramps are overuse and underuse. Overusing the muscles can tire them out, and when muscles tire, they tighten up. Foot and leg cramps are likely to occur when muscles are tight and tired, so over-training, over-exercising, or otherwise overusing the legs can lead to cramps. Not using the muscles enough can lead to muscle weakness, and weaker muscles are more likely to become tired than strong ones. Living a sedentary lifestyle is likely to lead to the weakening or degradation of muscles, which can in turn lead to tightness that will cause foot and leg cramps.
Another common cause of foot and leg cramps is dehydration and loss of electrolytes in the muscles. Muscles need proper delivery of oxygen in order to function correctly, and if the body is low on fluids, that oxygen delivery slows or stops. Drinking plenty of fluids before, during, and after physical activity can help prevent foot and leg cramps by ensuring oxygen delivery does not slow. The legs and feet are most susceptible to cramping when dehydration occurs, so it is important to stay hydrated to prevent cramping and other types of damage to the muscles of the legs.
Electrolytes are chemicals in the body that conduct electricity and are responsible for helping regulate muscle and nerve activity in the body. When the body becomes depleted of electrolytes, many adverse affects may occur, one of which is muscle cramps. Salt, calcium, and magnesium are common electrolytes used in the body, and when these substances become depleted, foot and leg cramps may occur. An athlete may choose to modify his or her diet to ensure more of these chemicals are present in the body, or he or she may choose to take vitamin and mineral supplements that can supply the body with the necessary electrolytes. A lack of electrolytes in the body may also exacerbate dehydration, leading to cramps.
Other factors that may contribute to foot and leg cramps include certain medications, improper training, and injury. Medications are often likely to cause dehydration, which can in turn lead to muscle cramps. If a person is taking medications that cause dehydration, he or she should be sure to hydrate regularly, even more so than he or she regularly would. Injuries to the legs or other parts of the body may lead to cramps as well. An injury to a hip, for example, may put extra strain on the foot and leg opposite the injured hip, causing the muscles in those areas to strain or contract abnormally. Improper training can lead to muscles becoming overtaxed, thereby making them susceptible to cramping.