## 3 Results and Discussion
### Mental Fatigue Inducement and Cognitive Performance  
Mental fatigue was exclusively induced by the standardized Stroop color-word task (ST) in most of the reviewed studies [41; 42; 43; 44; 45; 46]. The duration of ST was generally 30 min; however, in one study, the authors used protocol with 10 min only [41]. Except for [PERSON] et al. [43], all of the other reviewed articles in this field were dedicated to soccer. For the evaluation of soccer-specific skills, some authors [36; 37] used the Loughborough soccer passing test (LSPT) adapted from [PERSON] et al. [48]. This test consists of passing to the colored target area shown on gymasium benches and the participants' reaction to the examinators randomized color signals. Therefore, cognitive components play a significant role in this evaluation approach. Research showed no alteration in the LSPT performance time of sub-elite players (0.1 \(\pm\) 9.4%) [45]; however, a significant difference was observed in the under-18 youth players (17.5 \(\pm\) 12.3% ***) [44]. Youth soccer players in categories under-14 and under-16 were not significantly affected by mental fatigue (7.5 \(\pm\) 17.0% and 4.2 \(\pm\) 17.8%) [44]. One study showed no difference in LSPT total time between the pre- and post-fatigue assessment; however, the number of errors in mental fatigue conditions rose by mean 60% * [45]. An increase of penalty time (errors) in LSPT was observed in all groups of youth players with the highest mean values in the under-18 category (91% ***). We assume that mentally fatigued players tended to make more errors in sport-specific performance assessment, which includes the cognitive component. Furthermore, [PERSON] et al. [45] did not observe alterations of movement speed in LSPT, though intermittent running performance in a different study [44] deteriorated in all groups of youth players. It is considered that mental fatigue influences the motor component of movement, especially in endurance tasks. On the other hand, in shorter bouts, the cognitive abilities related to executive functions can alter. In addition, the previously described \"footbonaut\" soccer-specific evaluation [41] discovered a significant difference between pre and post mental fatigue conditions in speed of action parameters (\(-5.4\pm 12.4\%\) *), whilst ball control scores remained largely unaffected (0.7 \(\pm\) 4.0%). Mental fatigue impaired both the accuracy (\(-4.8\pm 5.7\%\) *; d = 0.89) and reaction time (\(-12.1\pm 21.2\%\) *; d = 0.49) of soccer-specific visual tasks in sub-elite soccer players [42]. This task consisted of various film-based simulations of soccer-specific situations with a variable number of defensive or offensive players. Response accuracy was very likely decreased in situation 5 vs. 3 formation (d = 1.00) and likely lower in formation 3 vs.1 (d = 0.49). Reaction time likely differed in all of the five showed formations. Furthermore, mentally fatigued elite cricket players performed worse in a reactive assessment based on multiple visual reactions to light sensors [43]. Reaction-time and hand-eye coordination scores did not become significantly worse after 30 min of ST (\(-\)9.5 \(\pm\) 11.9%). It is suggested that visual search and decision-making abilities deteriorated with mental fatigue inducement, as well as visual reaction ability which was affected slightly. A predominantly synergic effect of both mental and physical fatigue was observed in studies [46; 47] that used in-game performance analysis of players known as a Game Performance Assessment Instrument (GPAI). This approach, concomitantly with the equation for decision-making index (DMI), was adapted from [PERSON] and [PERSON] [49]. Players' performance was analyzed in simulated soccer games, which provided the additional sport-specific load. GPAI analysis showed a decrease in passing decision-making performance (DMI) following 30 ST compared to 15 ST (d = 0.31 *) and CON (d = 0.30 *). No significant difference was observed after 15 ST (\(p\) > 0.05). [PERSON] et al.