mental fatigue

Mental fatigue is a factor that may influence performance of chess players. However, effects of mental fatigue on performance of chess players are rarely investigated. Therefore, the aim of this study was to explore the effects of exposure to a mental fatigue protocol on memory function (pattern recall performance) of expert chess players. Thirty expert chess players (55-65 years-old) were randomly assigned into mental fatigue and control groups. Participants in the mental fatigue group were asked to (re-)place observed ordinary and random chess positions on a blank chessboard before and after exposing to a 30-minutes’ mental fatigue protocol. The control group followed the same procedure but they read a text about history of chess instead of exposing to mental fatigue protocol. Two ordinary and two random chess positions were used to measure pattern recall performances in pre- and post-tests. Visual Analogue Scale was used to measure the subjective rating of mental fatigue and motivation for upcoming pattern recall task. Results showed that exposing to mental fatigue protocol increased the subjective rating of mental fatigue significantly in the mental fatigue group. Moreover, motivation was not different between the groups before performing pattern recall task in posttest. Also, results revealed that exposing to mental fatigue protocol impaired pattern recall performance of expert chess players. Finally, expert chess players performed significantly better in recalling ordinary positions than random positions. Findings of the study can add to the existing knowledge on effects of mental fatigue on a variety of sporting context and also provide support for Chunking Theory of Memory and Template Theory.

Background: Anodal transcranial direct current stimulation (a-tDCS) is a new neuro-modulatory technique.Aim: This study aimed to investigate the effect of a-tDCS on dynamic balance after exhaustion.Material and Methods: Fifteen endurance-trained men voluntarily attended five separate sessions. In the first session, Maximal aerobic speed (MAS) was measured. Then, the participants were randomly assigned to four different conditions: 1. Mental fatigue (MF)+a-tDCS, 2. MF+sham (s-tDCS), 3. a-tDCS, and 4. s-tDCS. In each session, after dynamic balance measurement, the participants were exposed to the conditions and received 20 min of anodal tDCS over the dorsolateral prefrontal cortex (DLPFC). Then, the participants performed a submaximal endurance activity at 70% of MAS until exhaustion. Immediately after exhaustion, dynamic balance was measured again.Results: After exhaustion, the dynamic balance of the right leg under the a-tDCS condition was significantly higher than the MF+s-tDCS (P= 0.008). The dynamic balance significantly decreased from pre- to post-test in MF+s-tDCS and s-tDCS conditions (P= 0.0001). In the left leg, the dynamic balance under the a-tDCS condition was significantly higher than MF+s-tDCS (P= 0.025).Conclusions: Anodal stimulation of the DLPFC could be beneficial for the dynamic balance and may have a protective effect against the negative consequence of exhausting activity on the dynamic balance in endurance-trained men.