Sodium loss after exercising or from dehydration may cause muscle cramps. Though cramps don't usually result in any long-term damage they can cause incredible pain. Athletes in particular are at risk of losing sodium and other minerals from the body. Illnesses such as diarrhea can also deplete the body of healthy sodium levels, possibly leading to cramps.
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A muscle cramp, also commonly known as a charley horse, can cause sharp and often unbearable pain. It happens when the thin fibers found in your muscles start to contract uncontrollably -- often at a fast rate. This sends pain signals shooting to the brain, making even the most experienced athlete double over in pain. MayoClinic.com lists several possible reasons for cramping, from overuse to sweating. However, a lack of enough sodium in the body appears to be a major trigger for muscle cramps.
Without sodium, your muscles wouldn't work. Along with potassium and other electrolytes, sodium allows the body to generate nerve impulses. These impulses tell the muscle whether to contract or expand. You get much of your sodium through food. Sodium leaves the body in urine through the process of excretion. Sodium also escapes through sweat. Excess urination, sometimes as a result of taking diuretic medicine, also removes a lot of sodium.
When you exercise, you lose more sodium by sweating than other electrolytes, according to Michael F. Bergeron, Ph.D., from the Medical College of Georgia. The average athlete doing one hour of intense exercise may sweat out between 1 and 2.5 L of fluid, though you may lose more than that. Sweat contains sodium. The amounts vary depending on athlete fitness, but it may contain as much as 2,300 mg per liter. That's the same amount as your daily recommended level of dietary sodium in every liter.
Medical guidelines suggest lowering your intake of salt to avoid high blood pressure. While this is a sensible approach for most Americans, it doesn't take into account exercise or the needs of athletes. This means athletes need more sodium to avoid cramping and dehydration. Some sports drinks contain electrolytes, such as sodium, to help prevent cramps and fatigue. Not replenishing sodium, particularly during and after high-intensity activities, can lead to hyponatremia -- a serious lack of body sodium. For example, after the Hawaii Ironman competition around 30 percent of participants are hyponatremic. Make sure you get enough sodium while exercising.