Cortisol - Essential Adaptation Hormone in Exercise

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 “guilty” 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, Adlercreutz's 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.

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