Overtraining Syndrome one more piece of the Central Sensitivity Syndrome puzzle

Abstract

The initial focus of overtraining syndrome was physical overexertion with inadequate rest, causing severe chronic fatigue and decreased performance. The pathophysiological knowledge has subsequently evolved, and although the exact mechanisms of overtraining syndrome are unknown, several hypotheses arise. The most prominent of these are: the existence of an immunoneuroendocrine imbalance and dysfunction of the central nervous system and of the neuroendocrine axis. On the other hand, central sensitivity syndrome encompasses nosological entities that share the pathophysiological mechanisms that cause them, that is, an immunoneuroendocrine and mitochondrial dysfunction as well as an oxidative stress imbalance. The most common entities within central sensitivity syndrome are fibromyalgia, tension headache and/or migraine, chronic fatigue syndrome, irritable bowel syndrome, multiple chemical syndrome, electrosensitivity syndrome, irritable bladder syndrome, and restless leg syndrome, among others. The pathophysiological and clinical analogy between overtraining syndrome and central sensitivity syndrome raises the possibility of including overtraining syndrome within central sensitivity syndrome, since a stressful stimulus such as chronic overtraining coupled with unbalanced compensatory systems can generate, at a given time, immunoneuroendocrine sensitization and therefore central sensitivity syndrome.