All authors read and approved the final manuscript.”
“Background Participation in ultra-marathon running is of increasing popularity [1–5] VX-680 order where an ultra-marathon is a running race longer than the marathon distance of 42.195 km . Within the ultra-marathons, there is a difference between single stage races [1, 2, 6, 7] and multi-stage races [3, 5], where the distance is split into daily stages. Running an ultra-marathon is associated with different problems such as a change in body mass [1, 8–10], dehydration , a loss of skeletal muscle mass [3, 7], an increase in total body water [3, 4, 6, 11], overuse injuries of the lower limbs with especially knee injuries
 and an impaired renal function due to exertional rhabdomyolysis
, leading in extreme cases to a renal failure . Among these ultra-running associated problems, an increase in total body water has been reported [3, 4, 6, 11] and the development of peripheral oedemas has been described in this context in endurance athletes [4, TSA HDAC price 13, 14]. In single stage ultra-distance races, Stuempfle et al.  reported a fluid overload caused by excessive fluid consumption during cold weather in a 161-km race in Alaska leading to both an increase in plasma volume and a decrease in serum sodium concentration ([Na+]). A decreased serum [Na+] as well as an increase in total body water has also been reported for male 100-km ultra-marathoners  and it was presumed that the increase in total body water led to the development of oedemas . In contrast to male 100-km ultra-marathoners, total body water and serum [Na+] remained unchanged in female 100-km ultra-marathoners while drinking ad libitum . Apart from ultra-running, also
ADP ribosylation factor after a Triple Iron triathlon, both total body water and plasma volume increased and clinically selleck chemical visible oedemas of the feet persisted until four days after the finish of the race . An increase in total body water has also been reported for ten male multi-stage ultra-marathoners competing over 1,200 km with 17 consecutive stages . Presumably, both the damage of skeletal muscle leading to rhabdomyolysis and an impaired renal function was the main factor for this accumulation of body water, since these ultra-runners suffered a decrease of skeletal muscle mass . Exertional rhabdomyolysis due to exercise-induced myoglobinuria has been described before [7, 12]. In another multi-stage ultra-endurance exercise of five consecutive days of hill walking, an increase in leg volume in five male subjects due to fluid and sodium retention has been described . These authors reported an increase in aldosterone activity leading to an increase in serum [Na+], fluid retention and an increased shift of fluid from the intracellular to the extracellular fluid compartment.