Athletes are constantly searching for ergogenic aids to enhance their performance during long-duration events such as ultra-marathons and Ironman distance triathlons. These events, which typically last in excess of 8 hours, often involve significant losses of fluids and electrolytes. When taken to an extreme, these losses present great stresses to the various systems of the body. Race preparation and intra-event strategies include carbohydrate loading, hyperhydration and sodium intake. Here sodium and the role it plays in ultra endurance events are discussed.