Does Mental Fatigue Negatively Affect Outcomes of Functional Performance Tests?

The Impact of Mental Fatigue on a Strength Endurance Task: Is There a Role for the Movement-Related Cortical Potential?

PURPOSE

Several mechanisms have been proposed to explain how mental fatigue degrades sport performance. In terms of endurance performance, a role for an increased perceived exertion has been demonstrated. Using electroencephalography and, more specifically, the movement-related cortical potential (MRCP), the present study explored the neural mechanisms that could underlie the mental fatigue-associated increase in perceived exertion.

METHODS

Fourteen participants (age, 23 ± 2 yr; 5 women, 9 men) performed one familiarization and two experimental trials in a randomized, blinded, crossover study design. Participants had to complete a submaximal leg extension task after a mentally fatiguing task (EXP; individualized 60-min Stroop task) or control task (CON; documentary). The leg extension task consisted of performing 100 extensions at 35% of 1 repetition maximum, during which multiple physiological (heart rate, electroencephalography) and subjective measures (self-reported feeling of mental fatigue, cognitive load, behand motivation, ratings of perceived exertion) were assessed.

RESULTS

Self-reported feeling of mental fatigue was higher in EXP (72 ± 18) compared with CON (37 ± 17; P < 0.001). A significant decrease in flanker accuracy was detected only in EXP (from 0.96 ± 0.03% to 0.03%; P < 0.05). No significant differences between conditions were found in MRCP characteristics and perceived exertion. Specifically in EXP, alpha wave power increased during the leg extension task ( P < 0.01).

CONCLUSIONS

Mental fatigue did not impact the perceived exertion or MRCP characteristics during the leg extension task. This could be related to low perceived exertion and/or the absence of a performance outcome during the leg extension task. The increase in alpha power during the leg extension task in EXP suggests that participants may engage a focused internal attention mechanism to maintain performance and mitigate feelings of fatigue.

The effects of mental fatigue on fine motor performance in humans and its neural network connectivity mechanism: a dart throwing study

While it is well known that mental fatigue impairs fine motor performance, the investigation into its neural basis remains scant. Here, we investigate the impact of mental fatigue on fine motor performance and explore its underlying neural network connectivity mechanisms. A total of 24 healthy male university students were recruited and randomly divided into two groups: a mental fatigue group (MF) and a control group (Control). Both groups completed 50 dart throws, while electroencephalography (EEG) data were collected. Following the Stroop intervention, participants in the MF group exhibited a decrease in Stroop task accuracy and throwing performance, and an increase in reaction time along with VAS and NASA scores. The EEG data during dart-throwing revealed that the network connectivity strength of theta oscillations in the frontal and left central regions was significantly higher in the MF group compared with the Control group, while the network connectivity strength of alpha oscillations in the left parietal region was significantly enhanced. The interregional connectivity within the theta and alpha rhythm bands, particularly in the frontal-central-parietal network connections, also showed a significant increase in the MF group. Mental fatigue impairs dart throwing performance and is accompanied by increased connectivity in alpha and theta.

Mental fatigue impairs repeated sprint and jump performance in team sport athletes

OBJECTIVES

We tested whether mental fatigue (MF), induced by a cognitively-demanding task, would impair repeated sprint ability (RSA) and repeated jump ability (RJA) performance, and whether physical fatigue and MF would impair psychomotor vigilance.

DESIGN

Randomized within-participant design.

METHODS

After establishing baseline peak countermovement jump (CMJ), 18 male participants performed 12 maximal 20-m (10-m linear + 10-m directional) repeated sprints (RSA random test) followed by 12 maximal repeated CMJs (RJA test) subsequent to 30-min Stroop task (MF) or a documentary (Control). Peak and mean running time and height, percent decrement score (Sdec), blood lactate, heart rate and RPE were measured for CMJ, RSA, and RJA tests. MF (M-VAS) and psychomotor vigilance [psychomotor vigilance test (PVT)] were measured at baseline, after each condition, and after the RSA/RJA tests.

RESULTS

Compared to Control, the Stroop task elevated MF (p = .001), RPE ratings (all p < .031), and mean and Sdec performance in directional (but not linear) RSA (all p < .032) and RJA tests (all p < .034). PVT score worsened after Stroop task (p = .011) but not Control, declined after RSA/RJA tests in both conditions (all p < .023) and was lower in the MF condition (p = .029). No condition differences were noted for peak (CMJ, RSA and RJA tests) performance, blood lactate, and heart rate.

CONCLUSIONS

MF impairs directional RSA, and RJA performance. This impairment was linked with increased RPE and without physiological changes. The progressive impairment in PVT score suggests a cumulatively negative effect of mental and physical fatigue on psychomotor vigilance.

Age and Type of Task-Based Impact of Mental Fatigue on Balance: Systematic Review and Meta-Analysis

The role of cognition in balance control suggests that mental fatigue may negatively affect balance. However, cognitive involvement in balance control varies with the type or difficulty of the balance task and age. Steady-state balance tasks, such as quiet standing, are well-learned tasks executed automatically through reflex activities controlled by the brainstem and spinal cord. In contrast, novel, and challenging balance tasks, such as proactively controlling balance while walking over rugged terrain or reacting to unexpected external perturbations, may require cognitive processing. Furthermore, individuals with preexisting balance impairments due to aging or pathology may rely on cognitive processes to control balance in most circumstances. This systematic review and meta-analysis investigated the effect of mental fatigue on different types of balance control tasks in young and older adults. A literature search was conducted in seven electronic databases and 12 studies met eligibility criteria. The results indicated that mental fatigue had a negative impact on both proactive (under increased cognitive load) and reactive balance in young adults. In older adults, mental fatigue affected steady-state and proactive balance. Therefore, mentally fatigued older individuals may be at increased risk of a loss of balance during steady-state balance task compared to their younger counterparts.

Perceived cognitive fatigue has only marginal effects on static balance control in healthy young adults

We examined the influence of perceived cognitive fatigue on static balance control in healthy young adults to gain greater clarity about this issue than provided in previous research. Based on the prevailing assumption in pertinent literature, we hypothesized that the influence of cognitive fatigue on balance control depends on the attentional effort required by the balance tasks being performed. To test this hypothesis, 44 young adults (24 women and 20 men) were alternately assigned to either the experimental group that was cognitively fatigued (using the 16-min TloadDback-task with individualized settings) or the control group (who watched a documentary). Before and after the intervention, the participants performed six balance tasks that differed in (attentional) control requirements, while recording the center of pressure (COP). From these time series, sway variability, mean speed, and sample entropy were calculated and analyzed statistically. Additionally, perceived cognitive fatigue was assessed using VAS scales. Statistical analyses confirmed that the balance tasks differed in control characteristics and that cognitive fatigue was elevated in the experimental group, but not in the control group. Nevertheless, no significant main effects of cognitive fatigue were found on any of the COP measures of interest, except for some non-robust interaction effects related primarily to sample entropy. These results suggest that, in young adults, postural control in static balance tasks is largely automatic and unaffected by task-induced state fatigue.

Static and dynamic resting-state brain activity patterns of table tennis players in 7-Tesla MRI

Table tennis involves quick and accurate motor responses during training and competition. Multiple studies have reported considerably faster visuomotor responses and expertise-related intrinsic brain activity changes among table tennis players compared with matched controls. However, the underlying neural mechanisms remain unclear. Herein, we performed static and dynamic resting-state functional magnetic resonance imaging (rs-fMRI) analyses of 20 table tennis players and 21 control subjects using 7T ultra-high field imaging. We calculated the static and dynamic amplitude of low-frequency fluctuations (ALFF) of the two groups. The results revealed that table tennis players exhibited decreased static ALFF in the left inferior temporal gyrus (lITG) compared with the control group. Voxel-wised static functional connectivity (sFC) and dynamic functional connectivity (dFC) analyses using lITG as the seed region afforded complementary and overlapping results. The table tennis players exhibited decreased sFC in the right middle temporal gyrus and left inferior parietal gyrus. Conversely, they displayed increased dFC from the lITG to prefrontal cortex, particularly the left middle frontal gyrus, left superior frontal gyrus-medial, and left superior frontal gyrus-dorsolateral. These findings suggest that table tennis players demonstrate altered visuomotor transformation and executive function pathways. Both pathways involve the lITG, which is a vital node in the ventral visual stream. These static and dynamic analyses provide complementary and overlapping results, which may help us better understand the neural mechanisms underlying the changes in intrinsic brain activity and network organization induced by long-term table tennis skill training.

Mental fatigue does not affect static balance under both single and dual task conditions in young adults

The ability to control balance and prevent falls while carrying out daily life activities may require a predominantly controlled (cognitive) or automatic processing depending on the balance challenge, age, or other factors. Consequently, this process may be affected by mental fatigue which has been shown to impair cognitive abilities. Controlling static balance in young adults is a relatively easy task that may proceed automatically with minimal cognitive input making it insusceptible to mental fatigue. To investigate this hypothesis, static single and dual task (while concurrently counting backward by seven) balance was assessed in 60 young adults (25.2 ± 2.4 years) before and after 45 min of Stroop task (mental fatigue condition) and watching documentary (control), presented in a randomized counterbalanced order on separate days. Moreover, because mental fatigue can occur due to task underload or overload, participants carried out two different Stroop tasks (i.e., all congruent, and mainly incongruent trials) on separate days in the mental fatigue condition. Results of the study revealed a significantly higher feeling of mental fatigue after the mental fatigue conditions compared to control (p < 0.001). Similarly, the performance on congruent Stroop trials decreases with time indicating objective mental fatigue (p < 0.01). However, there was no difference in balance or concurrent task performance under both single and dual task assessments between the three conditions (p  > 0.05) indicating lack of effect of mental fatigue on static balance in this population. Therefore, future studies investigating this phenomenon in occupational or sport settings in similar population should consider using more challenging balance tasks.

Effects of mentally induced fatigue on balance control: a systematic review

The relationship between cognitive demands and postural control is controversial. Mental fatigue paradigms investigate the attentional requirements of postural control by assessing balance after a prolonged cognitive task. However, a majority of mental fatigue research has focused on cognition and sports performance, leaving balance relatively underexamined. The purpose of this paper was to systematically review the existing literature on mental fatigue and balance control. We conducted a comprehensive search on PubMed and Web of Science databases for studies comparing balance performance pre- to post-mental fatigue or between a mental fatigue and control group. The literature search resulted in ten relevant studies including both volitional (n = 7) and reactive (n = 3) balance measures. Mental fatigue was induced by various cognitive tasks which were completed for 20-90 min prior to balance assessment. Mental fatigue affected both volitional and reactive balance, resulting in increased postural sway, decreased accuracy on volitional tasks, delayed responses to perturbations, and less effective balance recovery responses. These effects could have been mediated by the depletion of attentional resources or impaired sensorimotor perception which delayed appropriate balance-correcting responses. However, the current literature is limited by the number of studies and heterogeneous mental fatigue induction methods. Future studies are needed to confirm these postulations and examine the effects of mental fatigue on different populations and postural tasks. This line of research could be clinically relevant to improve safety in occupational settings where individuals complete extremely long durations of cognitive tasks and for the development of effective fall-assessment and fall-prevention paradigms.

A plausible link between the time-on-task effect and the sequential task effect

Mental fatigue can be studied by using either the time-on-task protocol or the sequential task protocol. In the time-on-task protocol, participants perform a long and effortful task and a decrease in performance in this task is generally observed over time. In the sequential task protocol, a first effortful or control task is followed by a second effortful task. The performance in the second task is generally worse after the effortful task than after the control task. The principal aim of the present experiment is to examine the relationship between these two decrements in performance while concomitantly using a sequential task protocol and assessing the performance of the first effortful task as a function of time-on-task. We expect a positive correlation between these two decrements in performance. A total of 83 participants performed a 30-min fatiguing mental task (i.e., a modified Stroop task) or a control task followed by a time-to-exhaustion handgrip task. As expected, this protocol combining the time-on-task and sequential task protocols allowed us to observe (1) a decrease in performance over time during the Stroop task, (2) a worst performance in the handgrip task after the Stroop task by comparison to the control task, (3) a positive correlation between these two effects. The decrease in performance during the Stroop task also correlated with the subjective measures of boredom and fatigue, whereas the detrimental effect observed in the handgrip task did not. Our findings suggest that the two fatigue-related phenomena share a common mechanism but are not completely equivalent.

Gender differences in professional drivers’ fatigue level measured with BAlert mobile app: A psychophysiological, time efficient, accessible, and innovative approach to fatigue management

Addressing fatigue is useful in a variety of scenarios and activities. Fatigue has recently been studied from a psychophysiological standpoint. As a result, the expression and impact of peripheral and central fatigue has been evaluated. Driving is one occupation where tiredness has disastrous consequences. BAlert is a smartphone app that approaches exhaustion with psychophysiological measures. More specifically, it evaluates the level of fatigue via heart rate variability (HRV) data and the cognitive compromise via Stroop effect. The goal of this study is to determine if there are gender differences in fatigue levels among professional drivers using the BAlert app. Statistically significant differences were found in the number of hours awake, in different parameters of HRV (AVNN, PNN50, RMSSD, and SDNN), in the level of stress, as well as in the cognitive response evaluated through the app. The results are discussed and their implications for the management of work fatigue are presented.

Do Cognitive, Physical, and Combined Tasks Induce Similar Levels of Mental Fatigue? Testing the Effects of Different Moderating Variables

Experts have highlighted the importance of coaches knowing the level of mental fatigue (MF) induced by different tasks. This study aimed to compare the mentally fatiguing nature of cognitive, physical, and combined tasks and, additionally, assess the effect of different moderating variables on MF. Twenty-three physically active (16 males: Mage = 24 years; seven females: Mage = 22.57 years) participants performed three experimental sessions: (a) physically fatiguing: 30 min of cycloergometer work (at 65%-75% of maximum heart rate), (b) mentally fatiguing: 30 min of an incongruent Stroop task, and (c) mixed fatiguing: 30 min of combining the physically and mentally fatiguing protocols. Subjective MF (visual analog scale), reaction time (psychomotor vigilance task), and cognitive performance (Stroop) were measured throughout the different protocols. Results showed significant increments in subjective MF after all tasks, with the mental and mixed protocols showing significantly higher increases. Only the mentally fatiguing protocol caused significant impairments in reaction time. No significant effects of sex, years of experience, or degree of mental toughness were observed. These results suggest that the use of all these tasks, and especially the mentally fatiguing exercises, should be avoided immediately prior to competitions due to the negative consequences of MF on performance. Moreover, this effect seems to be independent of the sex, years of experience, or mental toughness of athletes.

Effects of Physical and Mental Fatigue on Postural Sway and Cortical Activity in Healthy Young Adults

Physical fatigue (PF) negatively affects postural control, resulting in impaired balance performance in young and older adults. Similar effects on postural control can be observed for mental fatigue (MF) mainly in older adults. Controversial results exist for young adults. There is a void in the literature on the effects of fatigue on balance and cortical activity. Therefore, this study aimed to examine the acute effects of PF and MF on postural sway and cortical activity. Fifteen healthy young adults aged 28 ± 3 years participated in this study. MF and PF protocols comprising of an all-out repeated sit-to-stand task and a computer-based attention network test, respectively, were applied in random order. Pre and post fatigue, cortical activity and postural sway (i.e., center of pressure displacements [CoP_d], velocity [CoP_v], and CoP variability [CV CoP_d, CV CoP_v]) were tested during a challenging bipedal balance board task. Absolute spectral power was calculated for theta (4–7.5 Hz), alpha-2 (10.5–12.5 Hz), beta-1 (13–18 Hz), and beta-2 (18.5–25 Hz) in frontal, central, and parietal regions of interest (ROI) and baseline-normalized. Inference statistics revealed a significant time-by-fatigue interaction for CoP_d (p = 0.009, d = 0.39, Δ 9.2%) and CoP_v (p = 0.009, d = 0.36, Δ 9.2%), and a significant main effect of time for CoP variability (CV CoP_d: p = 0.001, d = 0.84; CV CoP_v: p = 0.05, d = 0.62). Post hoc analyses showed a significant increase in CoP_d (p = 0.002, d = 1.03) and CoP_v (p = 0.003, d = 1.03) following PF but not MF. For cortical activity, a significant time-by-fatigue interaction was found for relative alpha-2 power in parietal (p < 0.001, d = 0.06) areas. Post hoc tests indicated larger alpha-2 power increases after PF (p < 0.001, d = 1.69, Δ 3.9%) compared to MF (p = 0.001, d = 1.03, Δ 2.5%). In addition, changes in parietal alpha-2 power and measures of postural sway did not correlate significantly, irrespective of the applied fatigue protocol. No significant changes were found for the other frequency bands, irrespective of the fatigue protocol and ROI under investigation. Thus, the applied PF protocol resulted in increased postural sway (CoP_d and CoP_v) and CoP variability accompanied by enhanced alpha-2 power in the parietal ROI while MF led to increased CoP variability and alpha-2 power in our sample of young adults. Potential underlying cortical mechanisms responsible for the greater increase in parietal alpha-2 power after PF were discussed but could not be clearly identified as cause. Therefore, further future research is needed to decipher alternative interpretations.

The acute effects of mental fatigue on balance performance in healthy young and older adults - A systematic review and meta-analysis

Cognitive resources contribute to balance control. There is evidence that mental fatigue reduces cognitive resources and impairs balance performance, particularly in older adults and when balance tasks are complex, for example when trying to walk or stand while concurrently performing a secondary cognitive task. We conducted a systematic literature search in PubMed (MEDLINE), Web of Science and Google Scholar to identify eligible studies and performed a random effects meta-analysis to quantify the effects of experimentally induced mental fatigue on balance performance in healthy adults. Subgroup analyses were computed for age (healthy young vs. healthy older adults) and balance task complexity (balance tasks with high complexity vs. balance tasks with low complexity) to examine the moderating effects of these factors on fatigue-mediated balance performance. We identified 7 eligible studies with 9 study groups and 206 participants. Analysis revealed that performing a prolonged cognitive task had a small but significant effect (SMDwm = -0.38) on subsequent balance performance in healthy young and older adults. However, age- and task-related differences in balance responses to fatigue could not be confirmed statistically. Overall, aggregation of the available literature indicates that mental fatigue generally reduces balance in healthy adults. However, interactions between cognitive resource reduction, aging and balance task complexity remain elusive.

Using Machine Learning to Identify Feelings of Energy and Fatigue in Single-Task Walking Gait: An Exploratory Study

The objective of this study was to use machine learning to identify feelings of energy and fatigue using single-task walking gait. Participants (n = 126) were recruited from a university community and completed a single protocol where current feelings of energy and fatigue were measured using the Profile of Moods Survey–Short Form approximately 2 min prior to participants completing a two-minute walk around a 6 m track wearing APDM mobility monitors. Gait parameters for upper and lower extremity, neck, lumbar and trunk movement were collected. Gradient boosting classifiers were the most accurate classifiers for both feelings of energy (74.3%) and fatigue (74.2%) and Random Forest Regressors were the most accurate regressors for both energy (0.005) and fatigue (0.007). ANCOVA analyses of gait parameters comparing individuals who were high or low energy or fatigue suggest that individuals who are low energy have significantly greater errors in walking gait compared to those who are high energy. Individuals who are high fatigue have more symmetrical gait patterns and have trouble turning when compared to their low fatigue counterparts. Furthermore, these findings support the need to assess energy and fatigue as two distinct unipolar moods as the signals used by the algorithms were unique to each mood.

Proof-of-Concept and Test-Retest Reliability Study of Psychological and Physiological Variables of the Mental Fatigue Paradigm

This study provided a proof-of-concept and test–retest reliability of measures frequently used to assess a mental fatigue paradigm. After familiarization, 28 healthy men performed (40-min) the Rapid Visual Information Processing (RVP) test in a test–retest design, having mental fatigue sensation, motivation, emotional arousal, total mood disturbance, and electroencephalography (EEG) in the prefrontal cortex measured before and after the test. EEG was recorded during a 3-min rest so that the power spectral density of theta (3–7 Hz) and alpha (8–13 Hz) bands was calculated. Pre-to-post RVP test changes in psychological and physiological domains were compared (paired-T tests), and absolute (standard error of measurement (SEM) and minimal difference (MD)) and relative reliability (intraclass correlation coefficient (ICC)) were calculated. The RVP test induced an increase (p < 0.05) in mental fatigue sensation (120.9% (109.4; 132.4)) and total mood disturbance (3.5% (−6.3; 13.3)), and a decrease in motivation (−7.1% (−9.2; −5.1)) and emotional arousal (−16.2% (−19.1; −13.2)). Likewise, EEG theta (59.1% (33.2; 85.0); p < 0.05), but not alpha band, increased due to RVP test. All psychophysiological responses showed poor-to-moderate relative reliability. Changes in mental fatigue sensation and motivation were higher than SEM and MD, but changes in EEG theta band were higher only than SEM. Mental fatigue sensation, motivation, and EEG theta band were sensitive to distinguish a mental fatigue paradigm despite true mental fatigue effects on theta activity may be trivial.

The effect of flaxseed on physical and mental fatigue in children and adolescents with overweight/obesity: a randomised controlled trial

Anti-inflammatory agents such as long-chain n-3 fatty acids have been recognised to improve disease-related fatigue. We hypothesised that α-linolenic acid may also benefit in reduction of fatigue in low-grade inflammation such as overweight/obesity. Seventy-two healthy children and adolescents with BMI > 25 kg/m2 were randomised to flaxseed (n 38) and puffed wheat (n 34) groups. Participants consumed isoenergetic amounts of either 20 g/d flaxseed or 25 g/d puffed wheat for 4 weeks. Fatigue, mood feelings (depression, anxiety and stress), appetite, energy intake, weight, height and waist circumference were measured. Analysis was performed based on per-protocol and intention-to-treat (ITT) approaches. Consumption of flaxseed decreased mental fatigue and caused a significant between-group difference (P < 0·001). Although no significant change in physical and total score of fatigue was observed in either group, a significant between-group difference occurred due to a more remarkable change in these parameters in the flaxseed group. General fatigue, motivation, activity and mood feelings did not change significantly between groups. Flaxseed showed less benefit than puffed wheat on anthropometric measures as it caused a smaller increase in height (0·53 (sd 0·89) v. 1·09 (sd 0·87) cm, P = 0·03) and reduction in BMI (-0·25 (sd 0·63) v. -0·67 (sd 0·56) kg/m2, P = 0·01) than puffed wheat. Appetite and waist circumference decreased in both groups, but no significant difference was observed between groups. In ITT analysis, only alteration in mental fatigue was significant. In conclusion, consumption of flaxseed may improve mental fatigue in children with overweight/obesity. However, because of smaller increase in height, it is better to hinder administration of flaxseed during periods of growth.

Relationship between the level of mental fatigue induced by a prolonged cognitive task and the degree of balance disturbance

This study investigated the effects of mental fatigue (MF) induced by a 90-min AX-continuous performance test (AX-CPT) on balance control by addressing the issue of the heterogeneity of individuals' responses. Twenty healthy young active participants were recruited. They had to carry out two balance tasks (sway as little as possible on a stable support with the eyes open and closed) when standing on a force platform before and after performing a 90-min AX-CPT. The NASA-TLX test was used to assess the subjective manifestations of MF. Objective cognitive performance was measured using results from the AX-CPT. Inter-individual differences in behavioral deterioration due to MF were analyzed with a hierarchical cluster analysis, which categorizes participants' behaviors into subgroups with similar characteristics. The cluster analysis revealed that the achievement of the AX-CPT induced various levels of MF and balance impairments within the whole sample. A significant relationship between the level of MF and the degree of balance disturbance was observed only when participants stood with the eyes open, thus suggesting that inter-individual differences in vulnerability to MF could stem from differences between subjects in the level of engagement of visual attention and/or from differences in field dependency for balance control. These findings show that the completion of the same prolonged demanding cognitive task induces a strong heterogeneity in subjects' responses, with marked individual differences in MF vulnerability that affect balance control differently according to the sensory context.

Does muscular or mental fatigue have an influence on the nociceptive flexion reflex? A randomized cross-over study in healthy people

BACKGROUND

The nociceptive flexion reflex (NFR) is a spinally-mediated withdrawal reflex occurring in response to noxious stimuli and is used as an electrophysiological marker of spinal nociception. Although it is well-documented that the NFR is subject to powerful modulation of several personal factors, the effects of experimentally induced fatigue on the NFR have not yet been examined. Hence, this study aimed to characterize if and how fatigue affects spinal nociception in healthy adults.

METHODS

The NFR of 58 healthy people was measured prior to and following rest and two fatiguing tasks performed in randomized order. The NFR was elicited by transcutaneous electrical stimulation of the sural nerve and objectified by electromyographic recordings from the biceps femoris muscle. An isokinetic fatiguing protocol was used to induce localized muscle fatigue of the hamstrings. The modified incongruent Stroop-word task was used to provoke mental fatigue. A linear mixed model analysis was performed to assess the influence of fatigue on the NFR.

RESULTS

Low-to-moderate levels experimentally induced localized muscle and mental fatigue did not affect the NFR in healthy adults. These results suggest that descending pain inhibitory processes to dampen spinal nociception are resistant to the effects of localized muscle and mental fatigue.

CONCLUSIONS

The relative robustness of the NFR to fatigue may be beneficial in both clinical and research settings where the influence of confounders complicates interpretation. Furthermore, the findings possibly help enhance our understanding on why even demanding cognitive/physical exercise-based treatment programs form effective treatment strategies for patients with chronic pain.

SIGNIFICANCE

The present study unraveled that low-to-moderate levels experimentally induced localized muscle and mental fatigue did not affect the NFR. These results suggest that descending pain inhibitory processes to dampen spinal nociception are resistant to the effects of localized muscle and mental fatigue. This relative robustness of the NFR may be beneficial in a clinical setting in which the evaluation of spinal nociception that is unaffected by clinical symptoms of fatigue may be useful (e.g. chronic fatigue syndrome, cancer-related fatigue, etc.).

The interaction of acute physical fatigue with three traditional functional performance tests and the reactive balance test

OBJECTIVES

To assess the impact of acute physical fatigue on traditional and neurocognitive functional performance tests in recreational athletes.

DESIGN

randomized counterbalanced cross-over study, pre-post design SETTING: laboratory PARTICIPANTS: Twenty recreational athletes (age = 24 ± 3 years) MAIN OUTCOME MEASURES: We evaluated fatigue impairments following a 30 s all-out effort in three traditional and one neurocognitive functional performance test. The traditional functional performance tests encompassed the single leg hop for distance (SLH), countermovement jump (CMJ) and Y-balance test (YBT). The neurocognitive functional performance test encompassed the reactive balance test (RBT). A 30 s modified Wingate was used to induce acute physical fatigue.

RESULTS

Acute physical fatigue was successfully induced as indicated by a significant increase in heart rate, systolic blood pressure, blood lactate levels and rating of perceived exertion (p < 0.001). Acute physical fatigue induced significant decreases in RBT accuracy (p = 0.004) and SLH performance (p < 0.001). YBT, CMJ and RBT visuomotor reaction time remained unaffected by acute physical fatigue.

CONCLUSIONS

Acute physical fatigue impairs SLH performance and decreases accuracy in the RBT. YBT and CMJ performance remained unaffected by acute physical fatigue. Clinicians should be aware of this divergent neurocognitive functional impairments caused by one all-out effort to allow well-informed selection of functional performance tests.

Mental Fatigue and Sport-Specific Psychomotor Performance: A Systematic Review

BACKGROUND

Mental fatigue (MF) is a psychobiological state that impairs endurance performance in healthy athletes. Recently, multiple studies indicated that MF could also impair sport-specific psychomotor performance (SSPP). Nevertheless, a systematic overview detailing the effects of MF on SSPP is currently lacking.

OBJECTIVE

The objective of this study is to collate relevant literature and examine the effect of MF on SSPP. A secondary aim was to create an overview of the potential subjective and physiological factors underlying this MF effect.

METHODS

PubMed (MEDLINE), Web of Science, PsycINFO and SPORTDiscus were searched (5th of November 2020). Studies were eligible when study outcomes encompassed any form of SSPP skill in a sport-specific context, the intervention was targeted to induce MF, and the population included healthy individuals. The presence of a manipulation check, to indicate the successful induction of MF, was obligatory for inclusion. Secondary outcomes were all outcomes (either physiological or psychological) that could explain the underlying mechanisms of the effect of MF on SSPP.

RESULTS

In total, 21 papers were included. MF was successfully induced in all but two studies, which were excluded from further analysis. MF negatively impacts a myriad of SSPP outcomes, including decision-making, reaction time and accuracy outcomes. No changes in physiological outcomes, that could underlie the effect of MF, were reported. Subjectively, only ratings of perceived of exertion increased due to MF in some studies.

CONCLUSIONS

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.