Limitations
We have to take into account that the number of present ultra-athletes in various disciplines and gender representation was different. Further we did not observe a urine dipstick for a urine colour, blood and myoglobin. However, direct measurement of myoglobin is less reli- able and not clinically useful [44]. Moreover, increased CK levels are associated with increased blood myoglobin [7, 38]. Hereafter, a development of rhabdomyolysis can delay several hours after the occurring of EAH due to the changes in intracellular [K+] and the restoring of cellular volume [14]. Peak CK level is about 48 to 96 h after its presentation [44]. In the marathon cyclists renal parameters remained elevated during 24 h of recovery [22, 23]. We had no possibility to observe ultra-athletes one or more days after the race; otherwise the danger of rhabdomyolysis could be higher