Can autonomic monitoring predict results in distance runners?

VICTORY ( í ) was the last word uttered by Philippides, before collapsing, at the end of the 42-km run from the fields of Marathon to Athens, where he had been sent to announce the victory against the Persians in 490 BC. In modern Olympic games, the marathon has been introduced as a 42.2-km road run, with a 2008 world record of 2 h, 3 min, and 59 s. It has been said that winning the Olympic marathon remains the ultimate accomplishment for a long-distance runner and that this requires strength, courage, and endurance but also something else, something the skeptics might call the blessing of the gods (9). The marathon has also become renown as the typical elite long-distance race, with thousands of runners participating in very popular races (such as the New York Marathon), organized in almost every part of the world. Accordingly, the training techniques and tactics to prepare for a marathon go well beyond the field of an elite sport and also interest laypeople or at least whoever might think to run a marathon, including the handicapped. Signs of the popularity of this specialty are easy to find. Google shows over six million hits for the word “marathon” and about two million for its combination with the word “training,” leaving interested individuals with (too) many options. In PubMed, “marathon” produces over 1,700 titles, and its combination with the word training over 400. Regarding the potential mechanisms involved in marathon training, strength and endurance are typically investigated by measuring maximal oxygen consumption (V̇O2max) (about 20 articles), since it has been said that V̇O2max and anabolic threshold can almost entirely explain the variation in marathon performance (18). About 23 studies address the psychological aspects, and new interest seems to be on the relationship between higher brain functions, marathon performance (12a), or the occurrence of symptoms. Winning performance likely requires a perfect interplay (12a) of training frequency, duration, and intensity with enough recovery to optimize the adaptation of both biological and psychological aspects. Overtraining (1) might induce a depression-like syndrome, inclusive of malaise and bodily symptoms, such as soreness that may guide in tailoring individual routines. It is also our experience in a different Olympic specialty (rowing) that subjective bodily symptoms observed before the competition might predict results in the subsequent race (7). In certain cases, the cortisol daily profile might help in assessing individual resilience to competitions stress, such as in pentathletes. In a sense, one might hypothesize that, like in everyday life, the stress of competing might be mirrored in functional parameters describing either subjective or objective elements of regulatory functions and notably the autonomic neural regulation of the cardiovascular system (11). Indirect Autonomic Assessment