Energy Availability in Male Athletes Across the Season

The aim of proposed cohort observational study is assessing the risk of low energy availability and relative energy deficiency in sport in competitive adult male athletes.

The changes in athlete's energy availability, health biomarkers in blood, gut microbiota composition and performance will be determined in 3 key stages across the season: during preparation, competition and transition period in a subset of athletes.

The study is investigating following specific aims in the cohort of male competitive athletes:

Correlation between energy availability and resting metabolic rate and metabolic functions across the season.

Correlation between energy availability and reproductive functions across the season.

Correlation between energy availability and hematological biomarkers across the season.

Correlation between energy availability and gut microbiota composition across the season.

Correlation between energy availability and performance across the season.

As the initial part of the research the screening for low energy availability, RED-S and eating disorder risk in a larger group of competitive athletes recognized by Olympic Committee of Slovenia will be performed via combination of validated and semi-validated questionnaires: Low Energy Availability in Males Questionnaire, RED-S specific screening tool, Eating Attitude Test (EAT-26) and Eating disorder Inventory - Drive for thinness score.

25 competitive male athletes will be invited for participation in the continuation phase of the research.

Depending on the type of sports, we will define appropriate time intervals for 3 planned laboratory visits. The first visit is planned in the preparation phase, when the workload, given the periodization of the training, is at its peak. The second visit is planned in the competition phase (presumably 6 moths after the 1st visit) and the third one in the transition phase, when the exercise load is the lowest.

The subjects will be informed about the procedure and the aim of the testing prior to its initiation at the introduction meeting. They will be notified about the right to terminate their participation at any moment. Prior to the initiation of the research they will be asked to sign the informed consent form. By doing that they will be informed about the exact procedure regarding how they will be required to keep a 4 day nutrition records with weighted quantities of food and how to keep the log regarding their physical activity. All subjects will be equipped with the acceleration meter.

In the framework of each laboratory visit, the subjects will come fasted, provide a stool sample and fill in the questionnaires, while we will perform anthropometric measurements, resting metabolic rate measurement by using the indirect calorimetry method in draw a venous blood sample. At the end of the visit, participants will undergo a performance test.

Eligibility Criteria:
Inclusion Criteria:

* National Sport Organization identified competitive female or male athlete
* Male athlete actively training for and racing in an Olympic sports event
* Age 18-40 years

Exclusion Criteria:

* Under 15 years old, older than 40 years
* Female
* Para-athlete
* Non active due to illness or injury