Based on the existing literature, we hypothesized that an ultra-marathon can lead to peripheral oedemas with an increase in the feet volume and that fluid overload would be associated PF-01367338 mouse with these increases. In case of fluid overload leading to an increase in the feet volume we hypothesized furthermore finding an association between changes in plasma [Na+] and the feet volume and a higher prevalence of EAH. In accordance with our

hypothesis, fluid intake was related to the change in feet volume. Furthermore, we found an association between the change in plasma [Na+] and the change in the feet volume. In addition, four subjects (5.3%) developed asymptomatic EAH with plasma [Na+] between 132 and 134 mmol/L. The most important finding in this study was that fluid intake was significantly and positively related to the change in the foot volume, where an increased fluid intake was leading to an increased volume of the foot. Both the change in the foot volume and fluid intake were significantly and negatively related to running speed. Faster runners were drinking less during the race, and their

foot volume tended to decrease. In accordance with our findings, Bracher et al. [32] demonstrated that fluid intake was positively related with the changes in the limb volumes. Since these authors found no association between fluid-regulating hormones and renal parameters with the changes in limb volumes, they concluded that fluid overload was the most likely mechanism leading to an increase in limb volumes. As fluid selleck compound intake was associated with the change in foot volume in the present study, we assume that no significant changes in total body water occurred in the present participants responsible for a possible development of peripheral oedemas. In case of excessive fluid intake with fluid overload, we would expect an increase in total

body mass [17, 19, 20], a decrease in plasma [Na+] [17–21], an increase in plasma volume and a decrease in haematocrit due to haemodilution [15]. In the present subjects, haematocrit decreased significantly and plasma volume increased by 5.3% indicating that fluid overload occurred. However, body Selleck Ibrutinib mass decreased, and both urine specific gravity and plasma [Na+] increased. In case of dehydration, as has been demonstrated in 12- and 24-hour ultra-marathoners [10], both a decrease in body mass and an increase in urine specific gravity have been reported [36, 37]. Furthermore, an increase in plasma [Na+] is expected when the water loss, including water loss by sweat, inducing dehydration is hypotonic compared with plasma [37]. The present subjects lost 2.4% of their body mass during the race, which was equal to mild dehydration and their post-race urine specific gravity was 1.024 g/ml indicating even a significant dehydration according to Kavouras [36].