Impact of allostatic biomarkers on health and performance

Abstract

The use of biomarkers in sports performance is essential to promote training balance, mainly because overtraining syndrome lacks standardized diagnostic criteria. The general objective of this work is to attribute a role to insulin, not only as a hormone used in the regulation of glycemia but also as a relevant and fundamental biomarker in adapting to each person's allostatic load, integrating it into the so-called allostatic biomarkers and granting a more systemic view than is usually done, considering its high impact not only on performance but also on health. For that, we evaluated the hormonal dynamics in two different conditions: (i) choosing one period of the season to assess the catabolic/anabolic relationships and the cardiovascular fitness effect on mitigate the deleterious effects of high catabolism presence; (ii) evaluating competitions that are considered as extreme in terms of fatigue and possible dysregulation of the endocrine system, such as ultramarathons and road cycling stage races. We observed that lower values of insulin were associated with higher levels of cortisol and ACTH in high-endurance male athletes, with cyclists with higher cardiovascular fitness, particularly above 70 mL/kg/min, exhibiting a higher threshold for the negative effects of cortisol on anabolic processes compared to their non-elite counterparts (lower cardiovascular fitness). That results suggested insulin's new and relevant role as a sports performance training monitoring biomarker more sensitive than testosterone, particularly elite level and that superior cardiovascular fitness may provide protection against the elevated catabolic hormonal concentrations found in road cyclist. From the competitive experimental approaches, we found a link between hormonal and RPE responses to an ultramarathon lasting an average of 24 hours, with the increase and maintenance of high cortisol and RPE perceived by the athletes and the decrease and maintenance of low insulin levels during the entire race. Also, it was demonstrated that the rest day during a twelve-days stage races enabled the body to achieve catabolic and anabolic efficiency once again. Instead of understanding how the body works, the main goal of these academic work was to understand how endurance athletes endocrine system reacts to extreme training and competition loads, developing knowledge capable of relating the variables tested with the performance and health of athletes, thus improving current practice and research.