Ultra-trail: Ultra-Health?

Background: The development of Mountain Ultra Marathon (MUM) raises several questions to health professionals, regarding the short or long-term consequences on the health of participants. Objective: to present the main acute and long-term effects of MUM on the main health issues usually studied among runners. Methods: Pragmatic review of the literature, including grey literature from the medical staff of the races, notably the Ultra-trail du Mont Blanc. Results: Concerning the acute effects, many studies show a severe transient inflammatory state, in particular related to eccentric loads encountered in downhill running, sometimes leading to an extracellular accumulation of water and to a muscular or even renal functional alteration, worsened when NSAIDs are used during the race. Structured and specific training seems to reduce this risk. Transient impairment of cardiac function and cardiac enzyme elevation are often discussed, but not related to symptoms in healthy subjects. In the long term, osteoarticular symptoms appear to be primarily related to a previous traumatic injury, such as ACL tear, rather than to the training load. Cardiac adaptations are similar to those of the “athlete’s heart” described in endurance athletes, which can lead to an increased risk of arrhythmias, usually benign, when training planning is too intensive. This point seems crucial to avoid over-training, and sometimes addiction to sport, whose prevalence seems worrying in this environment. Discussion: MUM is characterized by a long exercise duration but low intensity, which limits the duration of acute damage. The effects of the inflammation state that could become chronic in case of accumulation of races remain uncertain for health. New longitudinal studies are therefore needed, including behavioural and psychological dimensions.