LAUSR

We read with great interest the recent narrative review by Scheer et al. [1] emphasizing the mounting evidence that ultra-endurance running (UER) may lead to long-term health problems. We fully agree with the authors’ claim that UER has complex pathophysiological implications that have repercussions that may vary in the long term, and to which attention must be addressed. While the authors must be congratulated for this extensive review, we believe that their interpretation needs to be considered with some caution. Firstly, the definition used for long-term follow up—1 year—is debatable; in fact, several years of follow-up are necessary to evaluate the real long-term association and/ or causal relationship between covariates [2, 3]. Longer longitudinal studies following UER participants are needed to establish a more accurate relationship between UER participation and long-term health problem occurrence. Notably, studies investigating runners’ risk of death, which ultimately evaluate their real long-term risks, would be more appropriate [4]. Secondly, as reported by Scheer et al. [1], UER popularity has increased over the last two decades [5]; however, to date, no study has followed or is currently following UER participants since their first involvement in the sport, which would allow more precise conclusions about their long-term health issues. Moreover, the cited studies investigating the long-term health problems in UER participants lack the crucial definition of dose; the definition of “chronic or repeated UER” remains unclear. Thirdly, we believe that a multi-factorial approach should be used to assess the impact of UER practice, particularly with respect to age and speed of running. On most occasions, the aim of younger participants is to reach the finish-line as quickly as possible, which may explain a higher incidence of overuse injuries in this subgroup. Conversely, older athletes usually run more slowly and experience fewer overuse injuries [6]. Consequently, to assess the consequences of long-term participation in UER, longer follow-up cohort studies are needed to distinguish the impact of UER participation variables among different subgroups. Masters’ athletes have a lower all-cause mortality rate and an increased life expectancy compared with the general population [6]. Therefore, while we agree that the nature of the relationship between good health and regular exercise in masters’ athletes participating in UER is not established (is it association and/or causal?), we still believe that moderate regular exercise practice should follow the relationship previously described in French Olympians [2]. Finally, the potential risks reported by Scheer et al. [1] in young UER participants may not be as great as those related to a sedentary lifestyle. Therefore, we believe that careful thinking is required when advancing precautionary arguments against a form of physical activity in light of the proven benefits for younger people of engaging in physical activities [7]. While the authors [1] acknowledge the benefits This comment refers to the article available online at https:// doi. org/ 10. 1007/ s4027902101561-3, https:// doi. org/ 10. 1007/ s4027902201647-6.