## 2 Materials and Methods  
### Participants and Settings  
Individual sports clubs in Slovakia will be addressed with a request to participate in the study. From among collective sports, all clubs playing in the top two leagues within the three most preferred and mass sports in Slovakia will be approached--football, hockey, and floorball. From the individual sports we will address clubs that are engaged in combat sports--karate, boxing, Jiu-Jistu, Taekwondo, and MMA. The precondition for involvement in the study will be participation in the highest-level Slovak competitions and participation in international competitions. More detailed conditions are set by inclusion and exclusion criteria.  
The control group will consist of athletes who participate in the lower-level competitions of the particular team sports (3 rd to 5 th league), and combat sports athletes who participate in competitions at the regional level.  
Currently in soccer, there are 12 clubs in the First League and 16 clubs in the Second League in Slovakia. In hockey, there are 12 Extra League clubs and 11 First League clubs; in floorball there are 12 Extra League as well as First League clubs. On average, there are 25 players per club, making a total of 1875 players. Of the combat sports, we will choose Karate with 131 clubs operating in Slovakia, Jiu-Jitsu with 22 clubs, Judo with 49 clubs, Taekwondo with 25 clubs, MMA with 20 clubs, and Boxing with 107 clubs. Despite the large number of clubs covering combat sports, there are only around 250 athletes in Slovakia falling within the age and performance group under study.  
_Sample size_  
We calculated minimum sample size according to the estimation given in Daniel [103], where \(n=\text{Z2P}(1-P)/\text{d2}\) (Z = 2.576 for 99% level of confidence; P = 0.5 for expected sample proportion of 50%; d = 0.05 for the 5% margin of error). Based on this calculation, the minimum number was set at 320 athletes in team sports. The target cohort will consist of 840 athletes, from which the sample size will be determined by the average prevalence (50%). We set a higher number of \(n=400\) as we anticipated a 20% loss.  
In combat sports, the target cohort will consist of 141 athletes from which the sample size will be determined by the average prevalence (50%). Based on this calculation, the minimum number was set at 71 athletes. We set a higher number of \(n=85\) as we anticipated a 20% loss. Randomization will be carried out using Microsoft Office Excel 2016.  
_The inclusion and exclusion criteria_  
Inclusion criteria were as follows:  
Experimental group:  
High intensity of physical activity confirmed by the IPAQ questionnaire (Activities with a MET score over 8);Active membership in a club competing in 1 st or 2 nd highest league in team sports; participation in the highest-level combat sport competitions in Slovakia, including participation in some of the international competitions. Duration of training unit 90 min or more four times per week; Minimum training experience--4 years; Control group: Adult men between 18 and 35 years; Training frequency 1-2 times per week; Moderate intensity of physical activity confirmed by the IPAQ questionnaire (Activities with a 3.0 to 6.0 METs. Duration of training unit 90 min or more 1-2 times per week; Minimum training experience--4 years. Exclusion criteria were as follows: Irregular training participation; Body Mass Index (BMI) above 30 (in kg/m2); Not answering all questions. Currently interrupted sporting career lasting more than 2 months.