Introduction: this study analyses anthropometric changes in terms of body mass, height and body mass index (BMI), in 32 finishers of the Ultratrail-CSP-115. The aims of the study are: to analyse the differences of body mass, height and BMI between the start and the finish of the race; and to describe the evolution of the weight during the event. Methodology: the body mass, height and BMI were compared using a T-Student test. To describe the evolution of body mass during the race an analysis of variance (ANOVA) for repeated measures was used. Results: significant changes were observed in the analysis of both objectives. Discussion and conclusions: the results are consistent with other similar studies, although there are concretions and interesting nuances. It stresses the loss of body mass of runners, which makes it advisable to make measurements during the race to avoid negative health ... [Llegir més ...]