Nutrition in ultra-endurance racing – aspects of energy balance, fluid balance and exercise-associated hyponatremia Extreme endurance charges inevitably lead to bottlenecks in the field of nutrition. It comes to an energy deficit usually leads to a decrease in body mass in the sense of a reduction of the body fat and also the muscle mass. If the athlete tries to supply energy via excessive fluid intake and want to correct dehydration, it may result in a fluid overload that leads to an electrolyte track in the sense of a hyponatremia.
In addition, excessive fluid supply can come to a swelling of the feet. The details are described in http://www.medicinasportiva.pl/new/pliki/ms_2013_04_07_knechtle.pdf