Chapter 56 - Commentary

Abstract

Abstract In ultraendurance races, athletes face limits in nutrition regarding energy and fluid metabolism. An ultraendurance performance lasting for 24 h or longer leads to a mean daily energy deficit of ∼7000 kcal. This energy deficit leads to a decrease in body mass, covered by a decrease in both fat mass and skeletal muscle mass. The energy deficit cannot be prevented by adequate energy intake. To avoid dehydration during an ultraendurance performance, adequate fluid intake is required. In case of fluid overload, both exercise-associated hyponatremia (EAH) and swelling of limbs may occur. Adequate ad libitum fluid intake of ∼300–400 mL/h may prevent both EAH and swelling of limbs. To summarize, in ultraendurance races, an energy deficit seems to be unavoidable. Potential strategies might be to increase prerace body mass by a diet to increase fat mass and/or strength training to augment skeletal muscle mass. Another possibility could be increasing energy intake during racing by consuming a fat-rich diet. However, future studies are required to investigate these aspects.