Drinking plenty of water is essential to staying hydrated, but sometimes, H20 alone doesn’t cut it, says Dr. Matthew Sedgley , a physician specializing in sports medicine at MedStar Health . Those who do strenuous exercise, have a labor-intensive job or spend long periods in the heat may also need to replenish their electrolytes. “Electrolyte is a fancy word for minerals like sodium, potassium and magnesium, and they’re substances our bodies need to function,” he says. “Your body uses them as