To achieve peak performance and performance in elite athletes, extreme training loads are required. At the elite level, peak training volumes in sports such as swimming, cycling, triathlon and rowing can exceed 30 hours per week, resulting in significant exercise energy expenditure (EEE). In addition, performance capacity limitations in many sports are associated with ideal power (or force) to body mass ratios, which encourage changes in body mass and/or body composition through adjustments in training loads and energy intake (EI). The long-term combination of these efforts creates the conditions for potentially harmful physiological and, consequently, health consequences of training overload. These can be expressed as a spectrum of physiological changes that define the overtraining syndrome (OTS) and/or as consequences of hormonal and metabolic disorders due to low energy availability (LEA) for basal metabolism, which is expressed clinically or sub-clinically as the relative energy deficit syndrome in sports (RED-S). OTS is manifested in clinical practice as a syndrome of reduced athlete performance that cannot be explained by disease causes, while RED-S is a spectrum of hormonal, metabolic and functional disorders of the organism that arise as a result of a state of chronic LEA. Therefore, OTS and RED-S have many common etiopathogenetic pathways and symptoms and signs of insufficient or inadequate regeneration and recovery after exercise. LEA is one of the key pathogenetic mechanisms of both syndromes. Energy availability (EA) is defined as the difference between EI and EEE and is normalized according to lean body mass. The concept of LEA itself shows that it is a consequence of inadequate energy intake in relation to training loads (either due to insufficient energy intake, increased energy expenditure due to training, or a combination of both). The consequences of LEA are numerous and affect the top athlete both in terms of health and performance.

Appropriate and comprehensive regeneration after training, which includes both nutritional support and various other regeneration procedures (psycho-social support, relaxation techniques to reduce stress, physical procedures to reduce muscle damage after training, appropriate sleep hygiene as well as sleep improvement techniques) and of course appropriate medical support, reduces the risk of RED-S and OTS and allows the athlete to train optimally, achieve top results and at the same time remain healthy. Only in this way can top sport be truly healthy. The fundamental goal of the present project is to verify the effectiveness of various screening tests that could more accurately identify the deficient area of ​​response to training and regeneration in an individual athlete, and thus direct him/her to individual treatment more quickly.