
Mental fatigue has been defined as a psychobiological state induced by prolonged periods of demanding cognitive activity, that is characterized by subjective tiredness or lack of energy and impaired cognitive function, sports skills and physical endurance.

Mental fatigue accumulates.
Mental fatigue is the silent killer of performance that can not only develop acutely but also build in a cumulative manner from external factors such as media engagements, study, work commitments, repetitive daily tasks, over-analysis and environmental instability.
Research also has proven that physical training can enhance mental fatigue and speed up the fatigue process based on brain activation, functional connection, and complexity.
This is why athletes can experience high levels of mental fatigue over a sports season. The accumulation of mental fatigue can be the difference between winning and losing a game or a professional contract.

Your athletes may be
mentally fatigued right now.
The signs of mental fatigue are more subtle than physical fatigue and will fly under the radar to the untrained eye.

When performance is not optimal, athletes may not understand why, especially when they feel physically well and are not injured.
Mental fatigue can translate into silly mistakes and out-of-character performance.

Not everything boils down to a “bad day” under performance pressure, mental fatigue can look like a loss of focus, an overly emotional decision, an uncharacteristic miss, a loss of speed, accuracy, and even angry outbursts.
The higher the pressure, the higher the consequences of mental fatigue and the greater the likelihood of seeing mental fatigue affect your athlete’s performance.
How mental fatigue
impairs performance.
Mental fatigue has two separate components: it can affect drive by either,
Increasing the perceived effort
necessary for a given task (“I cannot do this, I am too exhausted”)

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Decreasing the perceived value
of the reward that can be obtained (“I do not want to do this, it is not worth it”).

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Neurophysiological theories confirm this dual nature of mental fatigue. It is suggested that mental fatigue can activate the inhibition centers of the brain, increasing perceived effort for a given task, hence decreasing drive and willingness to act.
On the other hand, it may also deactivate facilitative brain centers (normally responsible for motivated behavior and increased drive toward a reward), also resulting in decreased drive.
Mental fatigue impacts physical and cognitive performance. It affects planning, sensorimotor function, cognitive control, and emotion regulation, thus increasing the risk of error. In sports, Mental fatigue primarily affects psychomotor performance by affecting decision-making, accuracy, and reaction time.

Mental fatigue increases the time it takes to react to a visual stimulus, compromises the ability to decide on an appropriate response, and thus decreases stimulus-response accuracy. This results in delayed or unadjusted actions, which lessen psychomotor performance.

What is the solution to
mental fatigue?
Mental fatigue is unavoidable and if our brain is not resilient it will catch us sooner or later. Your body could be perfectly conditioned but will your brain hold you back?

Brain Endurance Training (BET) has been proven to condition the brain to withstand mental fatigue and physical fatigue.
The solution to mental fatigue involves two things,
01
Training
Carefully planning and executing brain endurance training programs in order to train the brain to be more resilient and to handle greater cognitive load without detrimental effects on performance.

02
Monitoring
Monitoring mental fatigue with DATA. Soma Technologies provides coaches with validated cognitive tasks (PVT, PVT-B), physiological measures (rMSSD, SDNN, BPM) and questionnaires (VAS-F, RME, RMF, RPE) that are designed to measure and monitor mental fatigue.

Mental Fatigue Research
The effects of mental fatigue on sport-related performance.
Mental Fatigue is known to increase subjective feelings of fatigue and to decrease cognitive performance, but its impact on physical performance remains poorly understood. The aim of this chapter was to review the results of 29 studies published between 2009 and April 2018 and focusing on the impact of mental fatigue on sport-related performance.
Mental Fatigue and Sport-Specific Psychomotor Performance: A Systematic Review.
Overall, the selected papers indicated that MF negatively affects SSPP. Research that assesses brain function, while evaluating the effect of MF on SSPP is essential to create further insight.
Does mental fatigue affect skilled performance in athletes? A systematic review.
Mental fatigue has a negative effect on various sports skills of high-level athletes, including their technical and decision-making skills; however, the impact is greater on offensive skills than that of defensive skills in terms of the role of athletes. Impaired executive functions may be responsible for the negative effects of mental fatigue on skilled performance.
Effects of Prior Cognitive Exertion on Physical Performance: A Systematic Review and Meta-analysis.
Findings demonstrate that cognitive exertion has a negative effect on subsequent physical performance that is not due to chance and suggest that previous meta-analysis results may have underestimated the overall effect.
The Effects of Mental Fatigue on Physical Performance: A Systematic Review.
The duration and intensity of the physical task appear to be important factors in the decrease in physical performance due to mental fatigue. The most important factor responsible for the negative impact of mental fatigue on endurance performance is a higher perceived exertion.
Mental fatigue impairs soccer-specific decision-making skill.
Mental fatigue impairs accuracy and speed of soccer-specific decision-making. These impairments are not likely related to changes in visual search behaviour.
Impact of mental fatigue on speed and accuracy components of soccer-specific skills.
Mental fatigue impairs short passing accuracy, but not movement speeds during the Loughborough Soccer Passing Test.
Mental fatigue alters the speed and the accuracy of the ball in table tennis.
Our results suggest that both mental fatigue, and muscle fatigue, significantly impair table tennis performance and therefore coaches should take into account both the physical and mental state of table tennis players to optimize performance.
The Influence of Mental Fatigue on Sessional Ratings of Perceived Exertion in Elite Open and Closed Skill Sports Athletes.
It seems mental fatigue may not significantly influence sRPE in individual training sessions, but may potentially have a cumulative effect that may affect the sRPE over a training week. This suggests monitoring mental fatigue independently of other training load (TL) measures may be worthwhile for strength and conditioning specialists and sports coaches to manage their athletes and researchers conducting studies into TL and performance.
The effect of mental fatigue on the performance of Australian football specific skills amongst amateur athletes.
Mental fatigue had a detrimental influence on the performance of AF specific skills. The findings may have implications for AF players who are required to sustain attention and concentration for prolonged periods before and during matches.
Effects of mental fatigue on soccer-specific performance in young players.
Soccer-specific technical performance was negatively affected by mental fatigue condition only in U18 in the LSPT
The effects of mental fatigue on cricket-relevant performance among elite players.
Mental fatigue, induced by an app-based Stroop test, negatively affected cricket-relevant performance.
How Physical Activities Affect Mental Fatigue Based on EEG Energy, Connectivity, and Complexity
It is concluded form the result that physical activities can enhance the mental fatigue and speed up the fatigue process based on brain activation, functional connection, and complexity. This result differs from the traditional opinion that physical activities have no influence on mental fatigue, and finds that physical activities can increase mental fatigue. This finding helps fatigue management through exercise instruction.
Effects of mental fatigue on exercise decision-making.
Findings suggest mental fatigue affects exercise decision-making by elevating subjective evaluation of the costs of engaging in exercise as opposed to sedentary alternatives.
Mental fatigue impairs technical performance and alters neuroendocrine and autonomic responses in elite young basketball players.
The data suggest that mental fatigue state is a key regulator of technical performance of basketball players and that mental fatigue seems to modulate endocrine and autonomic responses.
Effect of mental fatigue on decision-making skill and visual search behaviour in basketball players: an experimental and randomised study.
The mental fatigue induced by sport-based videogame impaired decision-making and altered visual search behaviour in basketball players.
Negative Effects of Mental Fatigue on Performance in the Yo-Yo Test, Loughborough Soccer Passing and Shooting Tests: A Meta-Analysis.
Overall, the findings presented in this review demonstrated that mental fatigue negatively impacts endurance-based running performance as well as soccer passing and shooting skills.
The Effect of Mental Fatigue on Cognitive and Aerobic Performance in Adolescent Active Endurance Athletes: Insights from a Randomized Counterbalanced, Cross-Over Trial.
RPE were significantly higher in the mentally fatigued than in the control conditions (p = 0.02) post-MSFT. Mental fatigue impairs aerobic and cognitive performance in active male endurance athletes.
Mental fatigue as a conditioner of the tactical and physical response in soccer players: a pilot study.
Mental fatigue modified the players’ movement dynamics on the pitch with reference to the quality of tactical actions and covered distance intensity.
Mental Fatigue and Basketball Performance: A Systematic Review.
Mental Fatigue impairs technical performance (free throws, three-point shots) and cognitive performance (TTF heuristics and decision-making) in basketball.
Mental fatigue impairs visuomotor response time in badminton players and controls.
These findings provide evidence that badminton players have better visuomotor response time than controls. However, they do not seem to be more resistant to the negative effects of mental fatigue on open skill-visuomotor performance.
Mental fatigue impairs physical activity, technical and decision-making performance during small-sided games.
Results showed that distance in acceleration covered per min, negative passes, passing accuracy, and shot accuracy were likely impaired than control task after a mental fatiguing protocol.
The limit to exercise tolerance in humans: Mind over muscle?
These results challenge the long-standing assumption that muscle fatigue causes exhaustion during high-intensity aerobic exercise, and suggest that exercise tolerance in highly motivated subjects is ultimately limited by perception of effort.
Effects of mental fatigue on attention: An ERP study.
The results indicate a dissociation in the effects of mental fatigue on goal-directed (top–down) and stimulus-driven (bottom–up) attention: mental fatigue results in a reduction in goal-directed attention, leaving subjects performing in a more stimulus-driven fashion.
Response inhibition impairs subsequent self-paced endurance performance.
The impairment in endurance performance observed after the incongruent Stroop task seems to be mediated by the higher perception of effort as predicted by the psychobiological model of endurance performance.
Cognitive fatigue effects on physical performance during running.
While previous research has examined the impact of cognitive tasks on physical tasks, this is the first study to examine a self-paced physical task, showing that cognitive activity indeed contributes significantly to overall performance. Specifically, cognitive fatigue increased the perception of exertion, leading to lesser performance on the running task.
Mental Fatigue Impairs Intermittent Running Performance.
Mental fatigue impairs intermittent running performance. This negative effect of mental fatigue seems to be mediated by higher perception of effort.
Mental Fatigue Impairs Soccer-Specific Physical and Technical Performance.
Mental fatigue impairs soccer-specific running, passing, and shooting performance.
Fatigue Induced by Physical and Mental Exertion Increases Perception of Effort and Impairs Subsequent Endurance Performance.
Perception of effort being identified as the variable altered by both prior physical exertion and mental exertion, future studies should investigate the underlying mechanisms increasing perception of effort overtime and in presence of fatigue during endurance exercise. Perception of effort should be considered not only as marker of exercise intensity, but also as a factor limiting endurance performance.
Mental Fatigue Alters Cortical Activation and Psychological Responses, Impairing Performance in a Distance-Based Cycling Trial.
Mentally fatigued recreational cyclists showed impaired performance, altered PFC activation and faster increase in RPE during a TT 20km.
Cognitive task performance causes impaired maximum force production in human hand flexor muscles.
Findings support current views that performance of cognitively demanding tasks diminishes central nervous system resources that govern self-regulation of physical tasks requiring maximal voluntary effort.
Cognitive Fatigue Influences Time-On-Task during Bodyweight Resistance Training Exercise.
Cognitively fatigued athletes have decreased time-on-task in bodyweight resistance training exercise tasks.
Impaired cognitive control and reduced cingulate activity during mental fatigue.
The present study documents that mental fatigue results in compromised error monitoring.
The effect of cognitive fatigue on decision making in sports.
Mental fatigue affects attention and the ability to use important information to perform efficiently.
The cardinal exercise stopper: Muscle fatigue, muscle pain or perception of effort?
Results of this two-part investigation suggest that perception of effort, rather than severe locomotor muscle fatigue or intolerably unpleasant muscle pain, is the cardinal exercise stopper during high-intensity aerobic exercise.
Kayaking performance is altered in mentally fatigued young elite athletes.
Mental fatigue has an almost certain negative impact on 2000-m kayaking performance in young elite athletes.
The impairing effects of mental fatigue on response inhibition: An ERP study.
We observed increased reaction time and miss rates, delayed NoGo-N2 latency and Go-P3 latency, and decreased NoGo-P3 amplitude, which indicated that mental fatigue may slow down the speed of the inhibition process, delay the evaluation of visual stimuli and reduce the availability of attentional resources. These findings revealed the underlying neurological mechanisms of how mental fatigue impaired response inhibition.
Effects of Mental Fatigue on Exercise Intentions and Behavior.
Mental fatigue alters the amount of physical effort people are willing to invest in an exercise workout and follow through with those intentions by doing less work. These are the first results showing people may deliberately adjust their physical effort to cope with mental fatigue.
Cognitive Fatigue Effects on Physical Performance During Running.
Cognitive fatigue increased the perception of exertion, leading to lesser performance on the running task.
Mental Fatigue Negatively Influences Manual Dexterity and Anticipation Timing but not Repeated High-intensity Exercise Performance in Trained Adults.
Manual dexterity and coincidence anticipation were significantly poorer post mental fatigue compared with control.
The effect of mental fatigue on critical power during cycling exercise.
Mental Fatigue suggests that cyclists were not able to fully expend W′ even though they exercised to volitional exhaustion.
Effect of mental fatigue on speed–accuracy trade-off.
The results suggested that movement was slowed in the presence of mental fatigue, maybe due to proactive changes occurring during the preparatory state of the movement, to preserve task success.
Mental fatigue impairs physical performance in humans.
Mental fatigue limits exercise tolerance in humans through higher perception of effort rather than cardiorespiratory and musculoenergetic mechanisms. Future research in this area should investigate the common neurocognitive resources shared by physical and mental activity.
What is mental fatigue in elite sport? Perceptions from athletes and staff
Mental fatigue impairs soccer-specific running, passing, and shooting performance.
Combating mental fatigue in soldiers.
Mental fatigue impairs both cognitive performance and subsequent physical performance
Prior Mental Fatigue Impairs Marksmanship Decision Performance.
Marksmanship judgment performance is significantly reduced when soldiers are mentally fatigued, although shot accuracy is not.