For an endurance athlete, keeping your electrolyte levels balanced is key for successful training and optimum performance. If your electrolytes levels are off, you could potentially compromise your workout, run, or race because of muscle fatigue or cramping. Balanced levels of electrolytes are necessary for your digestive, cardiac, muscular and nervous systems to function properly.
Electrolytes are sodium (Na+), potassium (K+), calcium (Ca 2+), magnesium, (Mg 2+), chloride (Cl-), phosphate (PO4 2-), bicarbonate (HCO3-), and sulfate (SO4 2-). Sodium, potassium, magnesium and calcium are the four major electrolytes that maintain the body’s fluid balance.
During a race or long run, if you rehydrate by drinking a lot of water which do not contain electrolytes, you may upset the balance of electrolytes in your bloodstream. This may lead to a dangerous condition called hyponatremia, where blood sodium levels drop too low. When this happens, your body's water levels rise, and your cells begin to swell. This swelling can cause many health problems, from mild to life-threatening.
Hyponatremia signs and symptoms may include:
During the 2015 New York City Marathon, elite runner and Oiselle Team Voleé member, Allie Burdick suffered with symptoms of hyponatremia. Afterwards she realized her pre race routine and in-race hydration failed to include proper electrolytes. Her excessive water consumption nearly ended her NYC Marathon with a DNF.
Sodium and other electrolytes assist rehydration during exercise in two ways. First, it increases the rate of fluid absorption from the gut into the bloodstream. And faster fluid absorption means faster hydration and less risk of dehydration.
The second benefit of electrolytes with regard to hydration is that it helps athletes maintain a higher blood volume, which in turn keeps body temperature and heart rate from rising during prolonged exercise. Research has shown that sodium does indeed have these effects. However, a study published in the Journal of Athletic Training found that the amount of sodium has less of an impact. High-sodium sports drinks were no more effective than a low-sodium sports drink in regulating body temperature and preventing "cardiac drift" (rising heart rate during prolonged exercise).
During long periods of endurance activities, experts often recommend athletes 'drink to thirst'. This varies by individual but most athletes fall between 14 and 18 fluid ounces per hour of exercise. Keep in mind some athletes will sweat more than others. And fluid losses will be higher in heat and humidity.
Sodium and potassium are not the only minerals lost during prolonged exercise. Trace minerals, minerals in smaller quantities (such as magnesium, copper, manganese, zinc, cobalt, selenium, silica, iodine, chromium, boron, and vanadium), play critical roles within the body's balanced ecosystem. Its important for endurance athletes to consume an electrolyte source that contains essential trace minerals to help regulate blood volume and maintain proper brain and muscle function during endurance training.