Cortisol - Essential Adaptation Hormone in Exercise

Abstract

Classical studies of H. Selye [27] on the general adaptation syndrome evidenced involvement of the adrenal cortex in adaptation processes. Accordingly, cortisol has been nominated as the adaptation hormone. However, during the past 15 ± 20 years several researchers in exercise physiology and sports medicine have had the opinion that the decreased ratio of testosterone/cortisol indicates a predominance of catabolism that is undesirable for adaptation and improvement of performance in athletes. In their opinion, an increased cortisol concentration is ªguiltyº of association with maladaptation.In 1986 Adlercreutz and coworkers [1] focused attention to the ratio testosterone/cortisol. They proposed using the ratio between free testosterone and cortisol as an indication of overstrain if the ratio decreases more than 30 % or if the ratio is less than 0.35´10 ±3 . This way, an extreme situation in the balance of anabolic and catabolic stimuli may be detected. However, the proposed quantitative measure was later forgotten and any decrease in the ratio was considered as a bad indication including an association with overtraining. Attention has not paid to the fact that Adlercreutz et al.[1] considered free but not total testosterone concentration in the blood. Moreover, Adlercreutzs team focused on the overreaching rather than overtraining. Actually, in a number of studies the decreased ratio was associated with improved performance of athletes [17,32]. In high-level rowers, the cortisol response to all-out exercise increased in conjunction with improved performance during a training year [28].The purpose of the present editorial is to comment the actual significance of cortisol in exercise and to correct several misunderstandings in evaluation of cortisol responses in athletes. Cortisol FunctionThis hormone has a wide spectrum of tasks in metabolic control (Fig. 1). Indeed, activation of catabolic processes and anti-anabolic action are included. However, these are essential tools for adaptation in the stress situation. The adaptive significance of catabolic changes consists, first of all, in creation of an increased pool of free amino acids. Therefore, branched chain amino acids can be used as additional substrate of oxidation. Moreover, free amino acids are available as ªbuilding blocksº for protein synthesis. Synthesis of several ultimately needed proteins is necessary during stress situation (including exercise), but it will be the dominating process during the late recovery period. Among metabolic inductors are those, which are produced in protein degradation (see Mader [20]). Catabolic processes continue also during the recovery period [35] ensuring the destruction of physiologically exhausted elements of protein structures in order to make possible their substitution by newly synthesized proteins.Protein synthesis is controlled at three levels: pre-translation level (induction), translation level, and post-translation level [2]. The post-translation control consists of adjusting the number of protein molecules to t...

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