Maintaining Fluid and Electrolyte Balance During Exercise

Abstract

The well-documented benefits and popularity of sports and fitness have led to an increased demand for products that not only replace sweat losses but also provide fuel for continued high-intensity metabolic demands. The twin risks of hypohydration and hyponatremia can lead to morbid and even fatal outcomes if rational replacement regimens are not followed, especially in endurance athletes and during hot or humid conditions. The avoidance of these complications of physical activity with oral replacement products has been documented primarily in high-impact, prolonged-duration events. Replacement fluid should contain water, sodium, and perhaps potassium to avoid overhydration-induced hyponatremia. Carbohydrates are added if muscle exertion is to continue for prolonged periods (>60 minutes in duration). The overuse of oral replacement products may yield the dilution of serum and intracellular electrolytes, hyperglycemia, and gastrointestinal distress. Baseline hydration and glucose status should be optimized before activity, and alterations in the amount and type of fluid ingested may be required for special populations such as children and individuals with chronic disease.