2.2. Participants 
A group of thirty-five semi-professional male ultramarathon runners took part in the study. All participants started in the Lower Silesian Mountain Runs Festival 2018 Ultra Marathon Race (characteristic—The study protocol was approved by the Bioethics Committee for Clinical Research at the Regional Medical Chamber in Gdańsk (decision no. KB-24/16). The study was registered as the clinical trial NCT03417700. 