Conversely, in a recent study of 45 male ultra-marathoners VX-809 cell line in a 161-km ultra-marathon held in the USA, 51.2% of the finishers presented with EAH [7]. The longer nature of the 161-km ultra-marathon coupled with the prolonged period spent on the trail were assumed to be the main reasons for the increased prevalence of

EAH, though when the data for five Blasticidin S consecutive years were combined, the prevalence of EAH was shown to be 15.1% and positively related to ambient temperature [11]. In another study, 8% of mountain ultra-marathoners competing in a 7-stage race (350 km) in Switzerland developed EAH [8], while mild asymptomatic EAH was found to occur in 4% of the volunteer ultra-endurance mountain runners in New Zealand [9]. Studies

investigating fluid intake and electrolyte metabolism balance have also been conducted in mountain ultra-endurance bike races. Studies of a single stage MTB race held in Switzerland [27, 28] and multi-stage races in South Africa, the Alps (i.e. Germany, Austria, Switzerland and Italy) [21, 22]. Similarly, no case of EAH was found in 65 ultra-endurance road cyclists competing in a 720-km ultra-cycling marathon in Switzerland [25]. On the contrary, 50% of the participants in an Alaskan cold weather race presented symptoms of EAH upon finishing the race [24]. Knechtle et al. described Combretastatin A4 for 200 athletes competing in different disciplines in Switzerland that 12 finishers (6%) developed EAH [8]. The prevalence of EAH was 13% in swimmers, 10.7% for road cyclists, 8% for both ultra-marathoners and mountain ultra-marathoners and no case in mountain bikers. Regarding different disciplines,

EAH was higher in running [1, 3, 4, 6–12, 38, 39, 44, 45] compared to cycling [8, 22, 25, 27, 28]. However, according to recent findings the comparison of cyclists and runners is problematic because there are fewer studies of bike races [8]. There is a dearth of data on the prevalence of EAH in races held in Europe. Therefore, the aim of the current study was to investigate Sclareol a series of ultra-endurance races held in the Czech Republic. Twenty-four-hour races held in different disciplines such as cycling and running are an ideal occasion to compare a prevalence of EAH between ultra-cyclists and ultra-runners. We intended to assess the prevalence of EAH in ultra-MTBers and ultra-runners in 24-hour races as single ultra-marathons and nearly non-stop performances without defined breaks with a specific load, and in a multi-stage race with an intermittent load with possibility of regeneration. We hypothesized an increased fluid intake during a 24-hour race for both cyclists and runners due to the large amount of fluids available at the refreshment stations in every lap.