Negative Effects Of Mental Fatigue Research Articles

Brain Stimulation Over the Motion-Sensitive Midtemporal Area Reduces Deleterious Effects of Mental Fatigue on Perceptual-Cognitive Skills in Basketball Players.

The objective of this study was to analyze the effect of anodal transcranial direct current stimulation (a-tDCS) over the motion-sensitive midtemporal area on perceptual-cognitive skills (visuomotor and basketball decision-making skills) in mentally fatigued basketball players. A total of 20 male basketball players were recruited. This was a randomized, double-blinded, and counterbalanced crossover study with two experimental conditions: a-tDCS and Sham. The participants completed the basketball decision-making task and visuomotor skill after performing a 60-min sport-based videogame task with anodal (i.e.,a-tDCS) or placebo (Sham) stimulation over the motion-sensitive middle temporal area. Worse response time was observed in visuomotor skill for Sham than a-tDCS postexperiment (p < .05). There was no main condition effect for accuracy of visuomotor skill (p > .05). There was more impairment in accuracy and response time in basketball decision-making skills for the Sham condition than a-tDCS (p < .05). Notably, a-tDCS over the motion-sensitive middle temporal area removed the negative effects of mental fatigue on perceptual-cognitive skills.

Mental fatigue and negative emotion among nurses during the COVID-19 pandemic.

COVID-19 is a major public health event affecting the people worldwide. Nurses are still under immense psychological pressure. This study aimed to explore the relationship between mental fatigue and negative emotions among frontline medical staff during the COVID-19 pandemic. The study was conducted in August 2020, which included 419 medical staff between 17 to 28 years. The Fatigue Scale, Multidimensional Mental Flexibility Questionnaire, Cognitive Fusion Scale, and Depression-Anxiety-Stress Brief Version Scale were used. During the data collection period, the pandemic was under control in China and continued worldwide. The results indicated that 27.7% of the medical staff experienced depression, and 32.3% of them feel stressed. Specifically, first, correlation analyses showed significant positive pairwise correlations between mental fatigue, psychological inflexibility, cognitive fusion, and negative emotions among nurses. Second, mediation model tests showed statistically significant mediating effects of psychological inflexibility and cognitive fusion between mental fatigue on nurses' negative emotions, and statistically, significant chain mediating effects of psychological inflexibility and cognitive fusion. Mental fatigue indirectly affects nurses' negative effects through the mediating effects of psychological inflexibility, cognitive fusion, and the chain mediating effects of psychological inflexibility and cognitive fusion, respectively. the negative effects of mental fatigue come from impairment of cognitive functioning, and interventions using acceptance and commitment therapy for mental fatigue and negative emotions are more effective since both psychological inflexibility and cognitive fusion are important components of the therapy.

How am I doing? Performance feedback mitigates the effects of mental fatigue on endurance exercise performance

Mental fatigue induced by an earlier cognitive task can impair performance on a subsequent physical task. The current study investigated whether such performance impairment could be mitigated by performance feedback. In an experimental sequential-task design, 63 sport science students completed a series of three tasks: 5-min physical (pre-test), 20-min cognitive, 5-min physical (post-test). Participants were randomly allocated to one of three groups: feedback (n = 23), no feedback (n = 20), control (n = 20). The physical tasks, which assessed force production during a self-paced rhythmic handgrip task as a measure of physical endurance performance, were performed with (feedback group) or without (no feedback group, control group) visual performance feedback. The cognitive tasks involved either completing a 2-back memory task to induce mental fatigue (feedback and no feedback groups) or watching a didactic film (control group). Self-report measures (fatigue, exertion, vigor, motivation) were collected throughout. The 2-back cognitive task increased mental fatigue, mental exertion and general fatigue in the feedback and no feedback groups compared to the control group. Relative to the pre-test physical task, post-test endurance performance declined in the no feedback group (−14.4%) but did not change in the control (−2.6%) and feedback (−2.4%) groups. This mitigation of performance effect was not accompanied by parallel changes in fatigue, exertion, vigor, or motivation. In conclusion, visual performance feedback mitigates the negative effects of mental fatigue on physical endurance performance.

Negative Effects of Mental Fatigue on Performance in the Yo-Yo Test, Loughborough Soccer Passing and Shooting Tests: A Meta-Analysis.

We aimed to examine the effects of mental fatigue on the Yo-Yo test and Loughborough soccer passing and shooting tests performance using a meta-analysis. The search for studies was performed through eight bibliographic databases (Academic Search Elite, AUSPORT, Cochrane Library, PsycInfo, PubMed/MEDLINE, Scopus, SPORTDiscus, and Web of Science). The methodological quality of the included studies was assessed using the PEDro checklist. A random-effects meta-analysis was performed for data analysis. After reviewing 599 search results, seven studies with a total of ten groups were included in the review. All studies were classified as being of good methodological quality. Mental fatigue reduced the distance covered in the Yo-Yo test (Cohen’s d: −0.49; 95% confidence interval [CI]: −0.66, −0.32). In the Loughborough soccer passing test, mental fatigue increased the original time needed to complete the test (Cohen’s d: −0.24; 95% CI: −0.46, −0.03), increased penalty time (Cohen’s d: −0.39; 95% CI: −0.46, −0.31), and decreased performance time (Cohen’s d: −0.52; 95% CI: −0.80, −0.24). In the Loughborough soccer shooting test, mental fatigue decreased points per shot (Cohen’s d: −0.37; 95% CI: −0.70, −0.04) and shot speed (Cohen’s d: −0.35; 95% CI: −0.64, −0.06). 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.

Does mental fatigue affect skilled performance in athletes? A systematic review.

Mental fatigue is a psychobiological state induced by a prolonged duration of demanding cognitive tasks. The effects of mental fatigue on physical performance have been well investigated in the literature. However, the effect of mental fatigue on skilled performance in sports remains unclear. This study aimed to report a comprehensive systematic review investigating the carryover effects of mental fatigue on skilled performance among athletes. A thorough search was conducted on PubMed, Web of Science, EBSCOhost (CENTRAL, SPORTDicus), and Scopus to select relevant literature, as well as on Google Scholar and sources of reference for grey literature. The selected literatures are centred on a mental fatigue protocol in which cognitive tasks are performed prior to athletic tasks. Only studies that used an experimental design to test two conditions, namely mental fatigue and non-mental fatigue, were selected. Eleven articles were chosen based on the selection criteria. Mental fatigue affects skilled performance in three sports: soccer, basketball, and table tennis. A decline in skilled performance (decreased accuracy, increased performing time etc) is relevant to impaired executive functions. Seven studies focus on offensive skills, whereas only two studies are associated with defensive skills. 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.

Physical Activity and Music to Counteract Mental Fatigue

Mental fatigue impairs both cognitive and physical performance. Bioactive substances (e.g., caffeine) have been used to counteract mental fatigue but could have side effects. The present study aimed to test two non-bioactive strategies to counteract mental fatigue: physical activity and listening to music. The participants first performed an arm-pointing task, then carried out a 32-min cognitively demanding task to induce mental fatigue (TLDB task), followed by another arm-pointing task at the end of the experiment. Between the end of the cognitively demanding task and the last arm-pointing task, 20 min went during which participants performed either 15 min of physical activity, of listening to music or of discussion (control). The subjective feeling of mental fatigue was assessed before each arm-pointing task and after the cognitively demanding task. For “physical activity” and “listening to music” groups, EEG was recorded at rest after each evaluation of subjective feeling of mental fatigue and during the cognitively demanding task. An increase in alpha power during the cognitively demanding task evidenced the presence of mental fatigue, without recovery during the following 20-min period. In the control condition, the arm-pointing task performance was deteriorated 20-min after the cognitively demanding task, while it remained stable after both physical activity and listening to music. Furthermore, recovery on the subjective feeling of mental fatigue was similar for both groups. The present results suggested that practicing physical activity and listening to music could be efficient strategies to counteract the negative effects of mental fatigue on motor performances.

The effects of intrinsic motivation on mental fatigue.

There have been many studies attempting to disentangle the relation between motivation and mental fatigue. Mental fatigue occurs after performing a demanding task for a prolonged time, and many studies have suggested that motivation can counteract the negative effects of mental fatigue on task performance. To complicate matters, most mental fatigue studies looked exclusively at the effects of extrinsic motivation but not intrinsic motivation. Individuals are said to be extrinsically motivated when they perform a task to attain rewards and avoid punishments, while they are said to be intrinsically motivated when they do for the pleasure of doing the activity. To assess whether intrinsic motivation has similar effects as extrinsic motivation, we conducted an experiment using subjective, performance, and physiological measures (heart rate variability and pupillometry). In this experiment, 28 participants solved Sudoku puzzles on a computer for three hours, with a cat video playing in the corner of the screen. The experiment consisted of 14 blocks with two alternating conditions: low intrinsic motivation and high intrinsic motivation. The main results showed that irrespective of condition, participants reported becoming fatigued over time. They performed better, invested more mental effort physiologically, and were less distracted in high-level than in low-level motivation blocks. The results suggest that similarly to extrinsic motivation, time-on-task effects are modulated by the level of intrinsic motivation: With high intrinsic motivation, people can maintain their performance over time as they seem willing to invest more effort as time progresses than in low intrinsic motivation.

On-the-Spot Binaural Beats and Mindfulness Reduces the Effect of Mental Fatigue

Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity which results in slower reaction time and attention deficits. The main aim of the current study was to investigate whether two types of interventions, specifically mindfulness and music/binaural beats, could reduce the negative effects of mental fatigue on subsequent cognitive processing. Recent studies show that individuals practicing mindfulness exhibit enhanced stress-coping and cognitive performance, including improved working memory and sustained attention. There is also evidence suggesting that using binaural beats increases sustained attention. To explore the influence of mindfulness and music on mentally fatigued individuals, four groups were recruited: a novice mindfulness group (n = 22), an experienced mindfulness group (n = 24), a music/binaural beats group (n = 23) and a control group (n = 21). The participants completed 5 phases of testing on the same day. Phase 1 consisted of completion of the BRUMS and a measurement of mind wandering using the SART. Phase 2 consisted of an induced state of mental fatigue using the 90-min AX-CPT. Phase 3 consisted of another BRUMS completion. Subjects were subsequently asked to complete one of the two 12 min. on-the-spot interventions (mindfulness or binaural beats). Phase 5 consisted of another completion of the SART. The results showed that the music group and the experienced mindfulness group were least affected by mental fatigue and its effect on the SART %NoGo success rate, whereas performance of the control group and the novice mindfulness group was reduced by mental fatigue. The findings are discussed in terms of using music/binaural beats to enhance cognitive control, with similar effects as mindfulness.

Can Creatine Combat the Mental Fatigue-associated Decrease in Visuomotor Skills?

The importance of the brain in sports was recently confirmed by the negative effect of mental fatigue (MF) on sport-specific psychomotor skills. Creatine supplementation improves strength but can also improve cognitive functioning. To explore the role of creatine in combating MF, we evaluated whether creatine supplementation counteracts the MF-associated impairment in sport-specific psychomotor skills. In 23°C, 14 healthy participants (4 females, 10 males; mean ± SD, age = 24 ± 3 yr, mass = 74 ± 13 kg, height = 179 ± 9 cm) performed a 90-min mentally fatiguing task (counterbalanced, crossover, and double-blinded; i.e., Stroop task) in two different conditions: after a 7-d creatine supplementation (CR; 20 g·d) and after a 7-d calcium lactate supplementation (placebo [PLAC]), separated by a 5-wk washout. In both conditions, a 7-min sport-specific visuomotor task, a dynamic handgrip strength endurance task, and a 3-min Flanker task was performed before and after the mentally fatiguing task. Physiological and perceptual responses were measured throughout the protocol. Handgrip strength endurance was higher in CR compared with PLAC (P = 0.022). MF impaired visuomotor response time (+4.4%; P = 0.022) and Flanker accuracy (-5.0%; P = 0.009) in both conditions. Accuracy on the Stroop task was higher in CR compared with PLAC (+4.9%; P = 0.026). Within the perceptual and physiological parameters, only motivation and vigor (P ≤ 0.027) were lower in CR compared with PLAC. Creatine supplementation improved physical (strength endurance) and prolonged cognitive (Stroop accuracy) performance, yet it did not combat MF-induced impairments in short sport-specific psychomotor or cognitive (Flanker) performance. These results warrant further investigation in the potential role of creatine in combating the MF-associated decrements in prolonged (e.g., 90-min soccer game) sport performance and suggest a role of brain phosphocreatine in MF.

Mental fatigue impairs visuomotor response time in badminton players and controls

PurposeIt has recently been reported that professional road cyclists have superior inhibitory control and resistance to mental fatigue compared to recreational cyclists. We sought to assess whether badminton players also have superior executive functions and whether they are more resistant to mental fatigue than controls on a visuomotor task. MethodsEleven healthy controls (mean ± SD; age: 25±4y; 6 females, 5 males) and nine healthy badminton players (age: 23±3y; 4 females, 5 males) performed two experimental trials in a randomized crossover order. Participants completed a baseline visuomotor task, followed by a Flanker task. Next, they performed either a 90-min Stroop task (MF) or watched a 90-min documentary (CON). Immediately thereafter, the Flanker task and the visuomotor task were completed again. Multiple physiological and psychological measures were assessed during the protocol. ResultsBadminton players’ and controls’ accuracy during the Stroop task decreased over time (p = 0.023). Subjectively, both groups perceived the Stroop task as more mentally demanding than the documentary (p < 0.001). In addition, higher mental fatigue was perceived in MF compared to CON, independently from group (p = 0.029). In the visuomotor task, controls as well as badminton players reacted significantly slower to the complex stimuli when mentally fatigued (~7%; p < 0.001). Badminton players (1109 ± 251 ms) outperformed controls (1299 ± 227 ms; p = 0.022) in the visuomotor task. However, this was not the case in the Stroop and Flanker task; in terms of accuracy and response time, badminton players and controls performed similarly. ConclusionThese 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. Furthermore, our study suggests that cognitive tasks with a larger motor component, such as our visuomotor task, are more sensitive to the negative effects of mental fatigue than traditional cognitive tasks (e.g. Flanker task) that have a very small motor component.

Mental fatigue impairs simple reaction time in non-athletes more than athletes

ABSTRACT Background: Cognitive enhancements are associated with persistent sport participation. The primary objective of this investigation was to assess mental fatigue during a prolonged simple reaction time task in athletes as compared to non-athletes. Methods: Forty men (20 athletes and 20 non-athletes; Age = 23.81 ± 2.28 years) completed a prolonged reaction time (RT) task of 51 min duration. The task included three periods of 17 min each, with no breaks, each period consisted of 200 RT trials. The participants’ ratings of mental fatigue were assessed with a modified visual analogue mood scale (VAMS) before and after the fatigue-inducing mental task. Results: Mental fatigue had a significant effect on both athletes and non-athletes (P ≤ .001). Athletes evidenced shorter RTs during the second and third periods of the prolonged reaction time task as compared with to non-athletes. Conclusion: This study suggested that athletes exhibit greater resistance to mental fatigue than non-athletes. It is therefore suggested that habitual exercise may reduce the negative effect of mental fatigue on a prolonged cognitive task.

A caffeine-maltodextrin mouth rinse counters mental fatigue.

Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity that has negative implications on many aspects in daily life. Caffeine and carbohydrate ingestion have been shown to be able to reduce these negative effects of mental fatigue. Intake of these substances might however be less desirable in some situations (e.g., restricted caloric intake, Ramadan). Rinsing caffeine or glucose within the mouth has already been shown to improve exercise performance. Therefore, we sought to evaluate the effect of frequent caffeine-maltodextrin (CAF-MALT) mouth rinsing on mental fatigue induced by a prolonged cognitive task. Ten males (age 23 ± 2years, physical activity 7.3 ± 4.3h/week, low CAF users) performed two trials. Participants first completed a Flanker task (3min), then performed a 90-min mentally fatiguing task (Stroop task), followed by another Flanker task. Before the start and after each 12.5% of the Stroop task (eight blocks), subjects received a CAF-MALT mouth rinse (MR: 0.3g/25ml CAF: 1.6g/25ml MALT) or placebo (PLAC: 25ml artificial saliva). Self-reported mental fatigue was lower in MR (p = 0.017) compared to PLAC. Normalized accuracy (accuracy first block = 100%) was higher in the last block of the Stroop in MR (p = 0.032) compared to PLAC. P2 amplitude in the dorsolateral prefrontal cortex (DLPFC) decreased over time only in PLAC (p = 0.017). Frequent mouth rinsing during a prolonged and demanding cognitive task reduces mental fatigue compared to mouth rinsing with artificial saliva.

Effects of Mental Fatigue on Endurance Performance in the Heat.

Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity and has been observed to decrease time trial (TT) endurance performance by ∼3.5% in normal ambient temperatures. Recently, it has been suggested that heat may augment the negative effect of mental fatigue on cognitive performance, raising the question whether it may also amplify the effect of mental fatigue on TT performance. In 30°C and 30% relative humidity, 10 endurance-trained male athletes (mean ± SD; age = 22 ± 3 yr, Wmax = 332 ± 41 W) completed two experimental conditions: intervention (I; 45-min Stroop task) and control (C; 45-min documentary). Pre- and postintervention/control, cognitive performance was followed up with a 5-min Flanker task. Thereafter, subjects cycled for 45 min at a fixed pace equal to 60% Wmax, immediately followed by a self-paced TT in which they had to produce a fixed amount of work (equal to cycling 15 min at 80% Wmax) as fast as possible. Self-reported mental fatigue was significantly higher after I compared with C (P < 0.05). Moreover EEG measures also indicated the occurrence of mental fatigue during the Stroop (P < 0.05). TT did not differ between conditions (I = 906 ± 30 s, C = 916 ± 29 s). Throughout exercise, physiological (HR, blood lactate, core, and skin temperature) and perceptual measures (perception of effort and thermal sensation) were not affected by mental fatigue. No negative effects of mild mental fatigue were observed on performance and the physiological and perceptual responses to endurance exercise in the heat. Most plausibly, mild mental fatigue does not reduce endurance performance when the brain is already stressed by a hot environment.

Determination of the Proper Rest Time for a Cyclic Mental Task Using ACT-R Architecture.

Objective Analysis of the effect of mental fatigue on a cognitive task and determination of the right start time for rest breaks in work environments. Background Mental fatigue has been recognized as one of the most important factors influencing individual performance. Subjective and physiological measures are popular methods for analyzing fatigue, but they are restricted to physical experiments. Computational cognitive models are useful for predicting operator performance and can be used for analyzing fatigue in the design phase, particularly in industrial operations and inspections where cognitive tasks are frequent and the effects of mental fatigue are crucial. Method A cyclic mental task is modeled by the ACT-R architecture, and the effect of mental fatigue on response time and error rate is studied. The task includes visual inspections in a production line or control workstation where an operator has to check products' conformity to specifications. Initially, simulated and experimental results are compared using correlation coefficients and paired t test statistics. After validation of the model, the effects are studied by human and simulated results, which are obtained by running 50-minute tests. Results It is revealed that during the last 20 minutes of the tests, the response time increased by 20%, and during the last 12.5 minutes, the error rate increased by 7% on average. Conclusion The proper start time for the rest period can be identified by setting a limit on the error rate or response time. Application The proposed model can be applied early in production planning to decrease the negative effects of mental fatigue by predicting the operator performance. It can also be used for determining the rest breaks in the design phase without an operator in the loop.

Superior Inhibitory Control and Resistance to Mental Fatigue in Professional Road Cyclists.

PurposeGiven the important role of the brain in regulating endurance performance, this comparative study sought to determine whether professional road cyclists have superior inhibitory control and resistance to mental fatigue compared to recreational road cyclists.MethodsAfter preliminary testing and familiarization, eleven professional and nine recreational road cyclists visited the lab on two occasions to complete a modified incongruent colour-word Stroop task (a cognitive task requiring inhibitory control) for 30 min (mental exertion condition), or an easy cognitive task for 10 min (control condition) in a randomized, counterbalanced cross-over order. After each cognitive task, participants completed a 20-min time trial on a cycle ergometer. During the time trial, heart rate, blood lactate concentration, and rating of perceived exertion (RPE) were recorded.ResultsThe professional cyclists completed more correct responses during the Stroop task than the recreational cyclists (705±68 vs 576±74, p = 0.001). During the time trial, the recreational cyclists produced a lower mean power output in the mental exertion condition compared to the control condition (216±33 vs 226±25 W, p = 0.014). There was no difference between conditions for the professional cyclists (323±42 vs 326±35 W, p = 0.502). Heart rate, blood lactate concentration, and RPE were not significantly different between the mental exertion and control conditions in both groups.ConclusionThe professional cyclists exhibited superior performance during the Stroop task which is indicative of stronger inhibitory control than the recreational cyclists. The professional cyclists also displayed a greater resistance to the negative effects of mental fatigue as demonstrated by no significant differences in perception of effort and time trial performance between the mental exertion and control conditions. These findings suggest that inhibitory control and resistance to mental fatigue may contribute to successful road cycling performance. These psychobiological characteristics may be either genetic and/or developed through the training and lifestyle of professional road cyclists.

A prolonged motor imagery session alter imagined and actual movement durations: Potential implications for neurorehabilitation

Mental practice with motor imagery improves motor performance, for example reducing the duration of goal-directed movements. However, it is not known whether an experimental session involving prolonged sequences of motor imagery induces mental fatigue and alters motor and mental performances. In this study, participants imagined 100 point-to-point arm movements combined with actual pointing movements every 10 or 50 imagined movements. Participants reported a subjective feeling of mental fatigue after imagining 100 pointing movements. When participants performed actual movements every 50 imagined movements, the duration of both actual and imagined movements increased at the end of the protocol. On the contrary, no change in actual and imagined movement duration was observed when participants performed actual movements every 10 imagined movements. These results suggested that the repetition of many imagined movements induced mental fatigue and altered the mental simulation and the actual execution processes of the movement. However, the regular execution of actual movements seemed to counteract the negative effect of mental fatigue as both actual and imagined movement duration remained constant with actual trials inserted between mental rehearsals. We suggest that during training or rehabilitation programs, actual movements should be executed and/or imagined movement duration should be controlled to avoid the negative effects of mental fatigue on motor performance.

Mental Fatigue Impairs Intermittent Running Performance.

The purpose of the study was to investigate the effects of mental fatigue on intermittent running performance. Ten male intermittent team sports players performed two identical self-paced, intermittent running protocols. The two trials were separated by 7 d and preceded, in a randomized-counterbalanced order, by 90 min of either emotionally neutral documentaries (control) or the AX-continuous performance test (AX-CPT; mental fatigue). Subjective ratings of fatigue and vigor were measured before and after these treatments, and motivation was recorded before the intermittent running protocol. Velocity, heart rate, oxygen consumption, blood glucose and lactate concentrations, and ratings of perceived exertion (RPE) were measured throughout the 45-min intermittent running protocol. Session RPE was recorded 30 min after the intermittent running protocol. Subjective ratings of fatigue were higher after the AX-CPT (P = 0.005). This mental fatigue significantly reduced velocity at low intensities (1.28 ± 0.18 m·s vs 1.31 ± 0.17 m·s; P = 0.037), whereas high-intensity running and peak velocities were not significantly affected. Running velocity at all intensities significantly declined over time in both conditions (P < 0.001). Oxygen consumption was significantly lower in the mental fatigue condition (P = 0.007). Other physiological variables, vigor and motivation, were not significantly affected. Ratings of perceived exertion during the intermittent running protocol were not significantly different between conditions despite lower overall velocity in the mental fatigue condition. Session RPE was significantly higher in the mental fatigue condition (P = 0.013). Mental fatigue impairs intermittent running performance. This negative effect of mental fatigue seems to be mediated by higher perception of effort.

Mental fatigue induced by prolonged self-regulation does not exacerbate central fatigue during subsequent whole-body endurance exercise.

It has been shown that the mental fatigue induced by prolonged self-regulation increases perception of effort and reduces performance during subsequent endurance exercise. However, the physiological mechanisms underlying these negative effects of mental fatigue are unclear. The primary aim of this study was to test the hypothesis that mental fatigue exacerbates central fatigue induced by whole-body endurance exercise. Twelve subjects performed 30 min of either an incongruent Stroop task to induce a condition of mental fatigue or a congruent Stroop task (control condition) in a random and counterbalanced order. Both cognitive tasks (CTs) were followed by a whole-body endurance task (ET) consisting of 6 min of cycling exercise at 80% of peak power output measured during a preliminary incremental test. Neuromuscular function of the knee extensors was assessed before and after CT, and after ET. Rating of perceived exertion (RPE) was measured during ET. Both CTs did not induce any decrease in maximal voluntary contraction (MVC) torque (p = 0.194). During ET, mentally fatigued subjects reported higher RPE (mental fatigue 13.9 ± 3.0, control 13.3 ± 3.2, p = 0.044). ET induced a similar decrease in MVC torque (mental fatigue –17 ± 15%, control –15 ± 11%, p = 0.001), maximal voluntary activation level (mental fatigue –6 ± 9%, control –6 ± 7%, p = 0.013) and resting twitch (mental fatigue –30 ± 14%, control –32 ± 10%, p < 0.001) in both conditions. These findings reject our hypothesis and confirm previous findings that mental fatigue does not reduce the capacity of the central nervous system to recruit the working muscles. The negative effect of mental fatigue on perception of effort does not reflect a greater development of either central or peripheral fatigue. Consequently, mentally fatigued subjects are still able to perform maximal exercise, but they are experiencing an altered performance during submaximal exercise due to higher-than-normal perception of effort.

Prolonged Mental Exertion Does Not Alter Neuromuscular Function of the Knee Extensors

The aim of this study was to test the hypotheses that prolonged mental exertion (i) reduces maximal muscle activation and (ii) increases the extent of central fatigue induced by subsequent endurance exercise. The neuromuscular function of the knee extensor muscles was assessed in 10 male subjects in two different conditions: (i) before and after prolonged mental exertion leading to mental fatigue and (ii) before and after an easy cognitive task (control). Both cognitive tasks lasted 90 min and were followed by submaximal isometric knee extensor exercise until exhaustion (endurance task), and a third assessment of neuromuscular function. Time to exhaustion was 13% ± 4% shorter in the mental fatigue condition (230 ± 22 s) compared with the control condition (266 ± 26 s) (P < 0.01). Prolonged mental exertion did not have any significant effect on maximal voluntary contraction torque, voluntary activation level, and peripheral parameters of neuromuscular function. A similar significant decrease in maximal voluntary contraction torque (mental fatigue condition: -26.7% ± 5.7%; control condition: -27.6% ± 3.3%, P < 0.001), voluntary activation level (mental fatigue: -10.6% ± 4.3%; control condition: -11.2% ± 5.2%, P < 0.05), and peripheral parameters of neuromuscular function occurred in both conditions after the endurance task. However, mentally fatigued subjects rated perceived exertion significantly higher during the endurance task compared with the control condition (P < 0.05). These findings provide the first experimental evidence that prolonged mental exertion (i) does not reduce maximal muscle activation and (ii) does not increase the extent of central fatigue induced by subsequent endurance exercise. The negative effect of mental fatigue on endurance performance seems to be mediated by the higher perception of effort rather than impaired neuromuscular function.

PII: S0920-9964(10)00210-0

Mental fatigue impairs both cognitive and physical performance. Bioactive substances (e.g., caffeine) have been used to counteract mental fatigue but could have side effects. The present study aimed to test two non-bioactive strategies to counteract mental fatigue: physical activity and listening to music. The participants first performed an arm-pointing task, then carried out a 32-min cognitively demanding task to induce mental fatigue (TLDB task), followed by another arm-pointing task at the end of the experiment. Between the end of the cognitively demanding task and the last arm-pointing task, 20 min went during which participants performed either 15 min of physical activity, of listening to music or of discussion (control). The subjective feeling of mental fatigue was assessed before each arm-pointing task and after the cognitively demanding task. For “physical activity” and “listening to music” groups, EEG was recorded at rest after each evaluation of subjective feeling of mental fatigue and during the cognitively demanding task. An increase in alpha power during the cognitively demanding task evidenced the presence of mental fatigue, without recovery during the following 20-min period. In the control condition, the arm-pointing task performance was deteriorated 20-min after the cognitively demanding task, while it remained stable after both physical activity and listening to music. Furthermore, recovery on the subjective feeling of mental fatigue was similar for both groups. The present results suggested that practicing physical activity and listening to music could be efficient strategies to counteract the negative effects of mental fatigue on motor performances.