Subjective Ratings Of Fatigue Research Articles

Towards a more individualised assessment of post-training fatigue in young footballers

Despite improvements in training load and fatigue monitoring, fatigue status may adversely affect intrinsic risk factors, particularly in young footballers. This study aimed to better individualise the fatigue effects of a 75-min football training session in young elite male players.Eighteen players (15.6 ± 1.7 years) completed a test battery before and after a football training session. Assessments included capillary blood samples (HCO3−, lactate, pH), subjective ratings of muscle soreness and fatigue. Functional tests included 30 m field sprint, laboratory drop jump (DJ) and horizontal force-velocity (H-FvP). The k-means method was applied to the first two dimensions of principal component analysis of changes in the H-FvP and DJ tests.Football training resulted in significant physiological changes and functional impairments, in particular an increase in interlimb asymmetry in the DJ test. No significant fatigue effect was found on the H-FvP test data. However, confirming the interest of combining the two tests, cluster analysis revealed two subgroups: In the H-FvP test, Cluster 1 decreased in V‾0 (p < 0.001) and P‾max (p < 0.01), while Cluster 2 decreased in F‾0 (p < 0.001). In the DJ test, Cluster 1 decreased in mean velocity (p < 0.01), relative mean and maximum power (p < 0.01) during push-off, while Cluster 2 decreased in relative mean push-off force (p < 0.01) and increased in interlimb asymmetry during braking (p < 0.01).This study highlights the contribution and complementarity of the H-FvP and DJ tests to improve individual screening for fatigue-related functional changes in footballers. Extrapolated values from the H-FvP test led to the identification of two subgroups with opposite fatigue profiles. One subgroup showed increased interlimb asymmetry in DJ, indicating an increased risk of injury with fatigue. These findings highlight the need for individualised fatigue assessment in young footballers.

The effect of age of acquisition on listening effort: Pupillometry and subjective measures

Bilinguals typically perform worse on speech-perception-in-noise relative to monolinguals, and bilinguals who learned the language later typically perform worse than those who learned it earlier. This decrement in performance has largely been attributed to the fact that both bilingualism and later acquisition result in comparatively less exposure to a language than monolingualism and earlier acquisition do. Though this effect of age of acquisition has been well-documented for speech recognition accuracy, less is known about how it affects listening effort. This study quantifies listening effort using three measures (pupil dilation, subjective effort ratings, and subjective fatigue ratings) for four listening conditions (quiet, easy, moderate, and hard). We collect these measures from four groups of participants: monolinguals, simultaneous bilinguals, early sequential bilinguals, and late bilinguals. Data collection is ongoing for a target sample size of 128 (32 per group). Based on related work, we expect greater listening effort for listeners with later ages of acquisition (e.g., late bilinguals relative to simultaneous bilinguals), and for that effect to increase with worsening acoustic quality (i.e., the hard relative to the easy condition). Preliminary results (N = 56) support these hypotheses. These data provide foundational insights into the relationship between bilingualism and listening effort.

Changes in perceived mental fatigue, physical fatigue and mood state during a 4‐day national junior orienteering competition preparation camp

AbstractMental fatigue (MF) has been shown to acutely impair the psychological responses and endurance running performance of orienteers. This study aimed to explore MF levels experienced by orienteers during a 4‐day competition preparation camp that consisted of simulated sprint, middle‐distance, long‐distance, relay and night races. Eleven national junior orienteers participated in the study (age: 15–17 years, height: 1.69 ± 0.07 m and body mass: 59.9 ± 5.22 kg). Subjective ratings of MF, motivation, stress, physical fatigue (PF) and tiredness were measured using a 100‐mm visual analogue scale. The Brunel Mood Scale (BRUMS) was utilized to assess the mood state of the orienteers. The self‐report measures were taken within 30 min of waking, immediately after the post‐training session, and after 24 and 48 h following the final training session. The pre–post orienteering training combined analysis showed that there was a moderate increase in perceived MF (ES = 1.06 [0.66, 1.45]), PF (ES = 1.07 [0.69, 1.45]) and BRUMS fatigue (ES = 0.74 [0.4, 1.1]) after orienteering training. At 48 h post the final training session, MF remained moderately elevated (ES = 0.86 [−0.07, 1.75]), while PF also remained elevated to a small extent (ES = 0.46 [−0.46, 1.39]) compared to the pre‐training values. A moderate impairment was still observed in BRUMS vigor (ES = −1.02 [−1.65, −0.36]), but BRUMS confusion scores were moderately lower (ES = −0.85 [−1.71, 0.04]) than pre‐training values. This study found that orienteering training induced acute MF, persisting for at least 48 h after the final session.

Fatiga mental y p´ádel: estado de la cuestión

Padel is attracting increased research interest. Although the focus has been on the physical and technical-tactical demands of the game, recently more attention is being paid to its mental demands and, more specifically, the importance of mental fatigue. This literature review provides an overview of mental fatigue in padel. First, we consider the mentally fatiguing nature of padel. Padel players must make complex decisions under high-time pressure, maintain self-confidence, and communicate with their partners in an emotionally charged context. With these cognitive demands, it is not surprising that padel matches and tournaments are mentally fatiguing. Second, we review evidence confirming that mental fatigue is detrimental for padel players’ performance, in agreement with findings observed in other sports. Third, we evaluate strategies to tackle mental fatigue and its effects on padel performance. Until now, the only proven long-term countermeasure is Brain Endurance Training. Finally, we make a series of recommendations for coaches and players to deal with mental fatigue, that focus on the quantification and modulation of mental fatigue among padel players. We strongly recommend i. to include subjective ratings of mental fatigue (i.e., VAS scale) before and after training and competitive matches, ii. to reduce the cognitive load of training before competitions by, for example, use positive feedback or habitual training exercises, and iii. to use Brain Endurance Training during non-competitive moments of the season.

Are Short Duration Naps Better than Long Duration Naps for Mitigating Sleep Inertia? Brief Report of a Randomized Crossover Trial of Simulated Night Shift Work

Objective We sought to test the effects of different duration naps on post-nap cognitive performance during simulated night shifts. Methods We used a randomized laboratory-based crossover trial design with simulated 12-hr night shifts and each participant completing three conditions of 72 hrs each (Clinicaltrials.gov; registration # NCT04469803). The three conditions tested included no-nap, a 30-min nap opportunity, and a 2-hr nap opportunity. Naps occurred at 02:00 hrs. Cognitive performance was assessed with the Brief 3-min Psychomotor Vigilance Test (PVT-B). Four PVT-B measures include: reaction time (RT in milliseconds (ms)), lapses (RT > 355 ms), false starts (reactions before stimulus or RT <100 ms), and speed (1,000/RT). The PVT-B was performed at the start of the simulated night shift (19:00), end of shift (07:00), pre-nap (02:00), and at 0 mins, 10 mins, 20 mins, and 30 mins following the 30-min and 2-hr nap conditions. Simultaneously, participants reported subjective ratings of fatigue and other constructs. Results Twenty-eight (15 female), mostly certified emergency medical technicians or paramedics, consented to participate. For all three conditions, looking within condition, PVT-B lapse performance at the end of the 12-hr simulated night shift (at 07:00) was poorer compared to shift start (p < 0.05). Performance on PVT-B speed, RT, and false starts were poorer at shift end than shift start for the no-nap and 30-min nap conditions (p < 0.05), but not for the 2-hr nap condition (p > 0.05). Compared to pre-nap measures, performance on the PVT-B assessed at 0 mins post-nap showed significant performance declines for lapses and speed for both the 30-min and 2-hr nap conditions (p < 0.05), but not at 10, 20, or 30 mins post-nap. After waking from the 2-hr on-shift nap opportunity (at 0 mins), participants rated sleepiness, difficulty with concentration, and alertness poorer than pre-nap (p < 0.05). Participants in the 30-min nap condition rated alertness poorer immediately after the nap (at 0 mins) compared to pre-nap (p < 0.05) Conclusions While sleep inertia was detectable immediately following short 30-min and long 2-hr nap opportunities during simulated night shift work, deficits in cognitive performance and subjective ratings quickly dissipated and were not detectable at 10–30 mins post-nap.

A single bout of passive exercise mitigates a mental fatigue-induced inhibitory control deficit.

Sustained cognitive effort associated with the psychomotor vigilance task (PVT) increases objective and subjective measures of mental fatigue and elicits a post-PVT inhibitory control deficit. In contrast, passive exercise wherein an individual's limbs are moved via an external force (i.e., mechanically driven cycle ergometer flywheel) provides a postexercise inhibitory control benefit linked to an exercise-based increase in cerebral blood flow. Here, we examined whether passive exercise performed concurrently with the PVT 'blunts' an inhibitory control deficit. On separate days, participants (N = 27) completed a 20min PVT protocol (control condition) and same duration PVT protocol paired with passive cycle ergometry (passive exercise condition). Prior to (i.e., baseline), immediately after and 30min after each condition inhibitory control was assessed via the antisaccade task. Antisaccades require a goal-directed eye movement (i.e., saccade) mirror-symmetrical to a target and provide an ideal tool for evaluating task-based changes in inhibitory control. PVT results showed that vigilance (as assessed via reaction time: RT) during control and passive exercise conditions decreased from the first to last 5min of the protocol and increased subjective ratings of mental fatigue. As well, in the control condition, immediate (but not 30-min) post-intervention antisaccade RTs were longer than their baseline counterparts-a result evincing a transient mental fatigue-based inhibitory control deficit. For the passive exercise condition, immediate and 30-min post-intervention antisaccade RTs were shorter than their baseline counterparts and this result was linked to decreased subjective ratings of mental fatigue. Thus, passive exercise ameliorated the selective inhibitory control deficit associated with PVT-induced mental fatigue and thus provides a potential framework to reduce executive dysfunction in vigilance-demanding occupations.

Effects of repetitive twice-weekly transcranial direct current stimulations on fatigue and fatigability in people with multiple sclerosis

Fatigue is associated with a dramatically decreased quality of life in people with multiple sclerosis (pwMS). It refers to a constant subjective feeling of exhaustion and performance decline, known as fatigability. However, inconsistency and heterogeneity in defining and assessing fatigue have led to limited advances in understanding and treating MS-associated fatigue. Transcranial direct current stimulation (tDCS) has emerged as a promising, non-pharmaceutical treatment strategy for subjective fatigue. However, whether repetitive tDCS also have long-term effects on time-on-task performance has not yet been investigated. This pseudorandomized, single-blinded, and sham-controlled study investigated tDCS effects on behavioral and electrophysiological parameters. 18 pwMS received eight twice-weekly 30 min stimulations over the left dorsolateral prefrontal cortex. Fatigability was operationalized as time-on-task-related changes in reaction time variability and P300 amplitude. Additionally, subjective trait and state fatigue ratings were assessed. The results revealed an overall decrease in subjective trait fatigue ratings that lasted at least four weeks after the stimulations. However, the ratings declined after both anodal and sham tDCS. No effects were found on subjective state fatigue and objective fatigability parameters. Linear Mixed Models and Bayesian Regression models likewise favored the absence of a tDCS effect on fatigability parameters. The results confirm the complex relationship between MS-associated fatigue and fatigability. Reliable and clinically relevant parameters need to be established to extend the potential of tDCS for treating fatigability. Furthermore, our results indicate that consecutive stimulations rather than twice-weekly stimulations should be the preferred stimulation scheme in future studies.

A machine learning approach for detecting fatigue during repetitive physical tasks

Prolonged and repetitive stress on muscles, tendons, ligaments, and nerves can have long-term adverse effects on the human body. This can be exasperated while working if the environment and nature of the tasks puts significant strain on the body, which may lead to work-related musculoskeletal disorders (WMSDs). Workers with WMSDs can experience generalized pain, loss of muscle strength, and loss of ability to continue working. Most WMSDs injuries are caused by ergonomic risks, such as repetitive physical movements, awkward postures, inadequate recovery time, and muscular stress. Fatigue can be seen as a detector of ergonomic risk, as the accumulation of fatigue can significantly increase the possibility of injury. Thirty participants completed a series of repetitive physical tasks over a six-hour period while wearing sensors to capture data related to heart rate and movement, while external embedded sensors captured ground reaction and hand exertion force. They also provided subjective ratings of fatigue at the start and end of the experiment. Classifiers for fatigue (high vs low) were constructed using three methods: linear discriminant analysis (LDA), k-nearest neighbor (kNN), and polynomial kernel-based SVM (P-SVM) and were validated using a tenfold cross-validation technique that was repeated a hundred times. Results of our supervised machine learning approach demonstrated a maximum accuracy of 94.15% using P-SVM for the binary classification of fatigue.

Translingual neurostimulation combined with physical therapy to improve walking and balance in multiple sclerosis (NeuroMSTraLS): Study protocol for a randomized controlled trial

IntroductionPhysical rehabilitation restores lost function and promotes brain plasticity in people with Multiple Sclerosis (MS). Research groups worldwide are testing the therapeutic effects of combining non-invasive neuromodulation with physical therapy (PT) to further improve functional outcomes in neurological disorders but with mixed results. Whether such devices enhance function is not clear. We present the rationale and study design for a randomized controlled trial evaluating if there is additional benefit to the synergistic pairing of translingual neurostimulation (TLNS) with PT to improve walking and balance in MS. Methods and analysisA parallel group [PT + TLNS or PT + Sham], quadruple-blinded, randomized controlled trial. Participants (N = 52) with gait and balance deficits due to relapsing-remitting or progressive MS, who are between 18 and 70 years of age, will be recruited through patient registries in Newfoundland & Labrador and Saskatchewan, Canada. All participants will receive 14 weeks of PT while wearing either a TLNS or sham device. Dynamic Gait Index is the primary outcome. Secondary outcomes include fast walking speed, subjective ratings of fatigue, MS impact, and quality of life. Outcomes are assessed at baseline (Pre), after 14 weeks of therapy (Post), and 26 weeks (Follow Up). We employ multiple methods to ensure treatment fidelity including activity and device use monitoring. Primary and secondary outcomes will be analyzed using linear mixed-effect models. We will control for baseline score and site to test the effects of Time (Post vs. Follow-Up), Group and the Group x Time interaction as fixed effects. A random intercept of participant will account for the repeated measures in the Time variable. Participants must complete the Post testing to be included in the analysis. Ethics and disseminationThe Human Research Ethics Boards in Newfoundland & Labrador (HREB#2021.085) & Saskatchewan (HREB Bio 2578) approved the protocol. Dissemination avenues include peer-reviewed journals, conferences and patient-oriented communications.

Cognitive fatigue-related sensory gating deficits in people with multiple sclerosis

BackgroundCognitive fatigue is highly prevalent in people with multiple sclerosis (pwMS) and significantly limits their quality of life. Fatigue can be subdivided into a subjective feeling of constant (trait) or current (state) exhaustion, as well as an objective performance decline, also known as fatigability. However, the current fatigue diagnosis in pwMS is purely subjective, leaving fatigability mostly unattended. Sensorimotor and sensory gating deficits have recently been described as possible objective markers for fatigability in healthy subjects. Thus, this study aimed to investigate the potential of prepulse inhibition (PPI) ratios and the P50 sensory gating suppression as surrogate markers for cognitive fatigue in pwMS. MethodsPPI and P50 sensory gating ratios were assessed before and after a 30-min fatigability-inducing AX- continuous performance task. Subjective trait fatigue was operationalized via self-report questionnaires, subjective state fatigue via visual analog scales (VAS), and fatigability via the change in both gating ratios. The data were analyzed using Linear Mixed Models and Pearson correlations. ResultsWe included 18 pwMS and 20 healthy controls (HC) in the final analyses. The task-induced fatigability was more pronounced in pwMS. While the initial PPI and P50 ratios were similar in both groups, P50 sensory gating was significantly disrupted after fatigability induction in pwMS. PPI, on the other hand, decreased in both groups. Moreover, initial P50 sensory gating ratios were negatively associated with subjective trait fatigue in pwMS, indicating that higher trait fatigue is associated with disrupted sensory gating. Finally, fatigability-related changes in P50 sensory gating were associated with the changes in VAS ratings, but only in HC. ConclusionsThis study demonstrated that P50 sensory gating is a promising objective fatigue and fatigability parameter. Importantly, P50 sensory gating correlated with subjective trait and state fatigue ratings. Our results extend the subjective fatigue diagnosis and broaden the understanding of pathophysiological neuronal mechanisms in MS-related fatigue. This is the first study to present fatigue-related disruption of sensory gating in pwMS.

Fatigue and Recovery of Muscles for Pulling Tasks.

Manual materials handling (MMH) contributes to musculoskeletal disorders (MSDs) in the workplace. The development and recovery of muscle fatigue are essential in work/rest arrangements for MMH tasks. A pulling experiment, including a muscle fatigue test and a muscle fatigue recovery test, was conducted. In the muscle fatigue test, the participant performed a pulling task on a treadmill with a walking velocity of 1 km/h until they could no longer do so. The load was either 30 or 45 kg. The maximum endurance time (MET) was recorded. The pull strength (PS) of the participant both before and after the pulling task was measured. The subjective ratings of muscle fatigue after the pulling task were recorded. In the muscle fatigue recovery test, the participant took a rest after performing the pulling task. The participants reported their subjective ratings of muscle fatigue on the CR-10 scale after taking a rest for a time period t, where t = 1, 2,…, 6 min. The PS of the participant was then measured again. It was found that the load significantly affected the MET for pulling tasks. The load was insignificant to the decrease of the PS, but was significant to the decrease rate (PS decrease per min) of the PS. The PS decrease rate for the 45 kg condition (30.8 ± 16.5 N/min) was significantly higher (p < 0.05) than that of the 30 kg condition (15.4 ± 5.5 N/min). The recovery time significantly affected the PS and CR-10. Two MET models were established to explore the development of muscle fatigue in pulling tasks. A PS model was constructed to describe the recovery of muscle force. A CR-10 model was proposed to show the subjective ratings of recovery. These models are beneficial for determining the work/rest allowance for pulling tasks.

Investigating the short-term effects of using full-body hospital personal protective equipment and changes in physical workload intensity on human physiological and cognitive performance

The present study investigated the short-term effects of using Personal Protective Equipment (PPE) and physical workload intensity on human physiological and cognitive performance among 21 males and 19 females. PPE1 consisted of a medical coverall and surgical mask, while PPE2 consisted of impermeable full-body coverall, shoe covers, latex gloves, N95 mask, and face shield. Objective assessments were heart rate, energy expenditure, core body temperature, clothing microclimate temperature and humidity, and cognitive performance were the continuous performance test and N-Back test. Subjective assessments included thermal sensation, perceived fatigue/skin wetness/clothing moisture. Using PPE2 and increased workload intensity significantly increased the values of all physiological parameters and the subjective ratings of fatigue, thermal sensation, skin wetness, and clothing moisture. Moreover, the participants’ cognitive performance was not affected by the type of PPE. Practitioner summary: Healthcare workers are at the highest risk in the fight against pandemics. Therefore, these people are required to use personal protective equipment. Using this equipment may have difficulties. The results show physiological strain and higher subjective ratings associated with using full-body hospital PPE and increased physical workload.

Modeling of the maximum endurance time of coal miners muscle fatigue for one-handed carrying tasks

To prevent safety production accidents caused by muscle fatigue among coal miners, a modified model of maximum tolerance time (TME) was established to predict the TME for one-handed handling tasks. Thirty-one participants including different types of coal miners volunteered to participate in one-handed handling of oil drums for loading, unloading and horizontal walking operations. The maximum voluntary contraction strength (fMVC), subjective fatigue rating (Erp) and TME of coal miners' backs and legs were measured before and after handling operations, as well as during the three task phases. An Erp one-dimensional linear regression prediction model was established under the effect of individual factors. A simplified TME prediction model was developed using power and exponential functions in the relative role of fMVC. A TME-modified model was further constructed considering the effects of weight and heart rate of coal miners. It was found that when fMVC ≤ 0.12, the simplified power model (median function model) provided higher estimates than the exponential model, and the predictions were closer to the true values. With fMVC < 0.2 or lower, incorporating indicators of instantaneous heart rate and body weight of coal miners, the TME modified model was used to accurately assess the TME of coal miners. It is suggested that workers engaged in manual handling operations on a daily basis should not carry a maximum weight of more than 22 kg on the back or legs to avoid musculoskeletal disorders that could lead to safety accidents.

Factors Predicting Training Delays and Attrition of Recruits during Basic Military Training.

Ensuring a balance between training demands and recovery during basic military training (BMT) is necessary for avoiding maladaptive training responses (e.g., illness or injury). These can lead to delays in training completion and to training attrition. Previously identified predictors of injury and attrition during BMT include demographic and performance data, which are typically collected at a single time point. The aim of this study was to determine individual risk factors for injury and training delays from a suite of measures collected across BMT. A total of 46 male and female recruits undertaking the 12-week Australian Army BMT course consented to this study. Injury, illness, attrition, and demographic data were collected across BMT. Objective measures included salivary cortisol and testosterone, step counts, cardiorespiratory fitness, and muscular endurance. Perceptions of well-being, recovery, workload, fatigue, and sleep were assessed with questionnaires. Baseline and mean scores across BMT were evaluated as predictors of injury and attrition using generalized linear regressions, while repeated-measures ANOVA was used for the group comparisons. From the 46 recruits, 36 recruits completed BMT on time; 10 were delayed in completion or discharged. Multiple risk factors for injury during BMT included higher subjective ratings of training load, fatigue, and stress, lower sleep quality, and higher cortisol concentrations. Higher ratings of depression, anxiety, and stress, and more injuries were associated with a higher risk of delayed completion. Higher concentrations of testosterone and higher levels of fitness upon entry to BMT were associated with reduced risk of injury and delayed completion of BMT. Ongoing monitoring with a suite of easily administered measures may have utility in forewarning risk of training maladaptation in recruits and may complement strategies to address previously identified demographic and performance-based risk factors to mitigate injury, training delays, and attrition.

Perfusion Imaging of Fatigue and Time-on-Task Effects in Patients With Parkinson's Disease.

Fatigue is a highly prevalent and debilitating non-motor symptom in Parkinson’s disease (PD), yet its’ neural mechanisms remain poorly understood. Here we combined arterial spin labeling (ASL) perfusion functional magnetic resonance imaging (fMRI) with a sustained mental workload paradigm to examine the neural correlates of fatigue and time-on-task effects in PD patients. Twenty-one PD patients were scanned at rest and during continuous performance of a 20-min psychomotor vigilance test (PVT). Time-on-task effects were measured by the reaction time changes during the PVT and by self-reported fatigue ratings before and after the PVT. PD subjects demonstrated significant time-on-task effects, including progressively slower reaction time on the PVT and increased post-PVT fatigue ratings compared to pre-PVT. Higher levels of general fatigue were associated with larger increases in mental fatigue ratings after the PVT. ASL imaging data showed increased CBF in the right middle frontal gyrus (MFG), bilateral occipital cortex, and right cerebellum during the PVT compared to rest, and decreased CBF in the right MFG at post-task rest compared to pre-task rest. The magnitude of regional CBF changes in the right MFG and right inferior parietal lobe correlated with subjective fatigue rating increases after the PVT task. These results demonstrate the utility of continuous PVT paradigm for future studies of fatigue and cognitive fatigability in patients, and support the key role of the fronto-parietal attention network in mediating fatigue in PD.

Nature Scenes Counter Mental Fatigue-Induced Performance Decrements in Soccer Decision-Making.

BackgroundIt has been well investigated that nature exposure intervention can restore directed attention and improve subsequent cognitive performance. The impairment of decision-making skills in mentally fatigued soccer players was attributed to the inability of attention allocation. However, nature exposure as the potential intervention to counter mental fatigue and improve the subsequent decision-making skill in soccer players has never been investigated.ObjectsThis study aimed to evaluate the effects of nature exposure intervention on decision-making skills among mentally fatigued university soccer players. Moreover, different durations of nature exposure were also evaluated.MethodsA random control between-subject design was adopted. Players were randomly assigned into six groups with three different durations of the experimental group compared with the corresponding control group (4.17 min: Exp 1 vs. Con 1; 8.33 min: Exp 2 vs. Con 2; and 12.50 min: Exp 3 vs. Con 3). All players were first mentally fatigued by performing a 45-min Stroop task; then, they viewed virtual photos of natural or urban scenes; and finally, they performed a soccer decision-making task.ResultsThe subjective ratings of mental fatigue were significantly higher following the Stroop task. Only Exp 3 (12.50 min viewing natural scenes) significantly improved decision-making reaction time compared with Con 3 (p = 0.09). Moreover, the accuracy slightly increased in Exp 3 after the intervention.ConclusionIn line with attention restoration theory, nature exposure significantly improved decision-making skills in mentally fatigue university players. However, the duration must be 12.50 min for each stimulus to stay longer to attract involuntary attention.

Mental Fatigue Impairs Postural Stability in Older Adults

ABSTRACT Purpose: Postural instability can increase the risk of a fall in older adults. In this study, the impact of mental fatigue on postural stability among healthy older adults was investigated. Method: Participants were randomly divided into two groups: experimental and control groups. Postural stability of all participants was tested using the Biodex Balance System (BBS) before and immediately after watching a 30-min documentary program (control group) or completing a 30-min Stroop task (experimental group). Subjective ratings of mental fatigue were measured before and after the Stroop task or watching documentary program. Results: The results indicated that experimental group revealed higher stability scores in the posttest compared to pretest (P ≥ 0.001). However, there were no significant differences for BBS scores between pre and posttest in control group (P = .688). In addition, posttest of subjective ratings of mental fatigue was significantly different between experimental and control groups. Finally, there was also evidence of an association between Visual analog scale and BBS scores in the experimental group (rs = 0.712, P = .002). Conclusions: Mental fatigue caused by Stroop task had a negative impact on postural stability in older adults. This may be due to reduction in attentional resources that was caused by mental fatigue. Thus, mental fatigue could be considered as a risk factor for increased risk of falls in older adults

Transcranial Direct Current Stimulation Reduces the Negative Impact of Mental Fatigue on Swimming Performance

ABSTRACT. The issue of using transcranial direct current stimulation (tDCS) to improve sport performance has recently been a topic of interest for researchers. The purpose of this study was to examine the effect of tDCS over left dorsolateral prefrontal cortex (DLPFC) on mental fatigue and physical performance in professional swimmers. Fifteen professional swimmers were randomly assigned in a single-blinded, randomized, counterbalanced order to sham, anodal and cathodal stimulation conditions. Mental fatigue was induced by using a 60-min modified Stroop color-word task. Subjective ratings of mental fatigue were measured before and after the stroop task. The results showed that only anodal tDCS of the left DLPFC reduces adverse effects of mental fatigue in 50-meter swimming performance, whereas cathodal stimulation had no significant effect.

139 Does Extraversion Predict Subjective Ratings of Sleepiness and Performance During Sleep Deprivation?

Abstract Introduction Repeated exposure to total sleep deprivation (TSD) within individuals has demonstrated task-specific, trait-like individual differences in cognitive impairment and subjective sleepiness. Research has suggested that introversion/extraversion may predict individual vulnerability to TSD. While previous analyses have found that extraversion does not reliably predict objective performance impairment on the psychomotor vigilance test (PVT) during TSD, it is not known whether extraversion may predict individuals’ subjective responses to TSD, including subjective ratings of sleepiness, fatigue, mood, performance, and effort. Methods N=21 healthy adults (aged 21-38; 9 women) completed three 4-day/3-night laboratory sessions – each including a baseline night, 36h TSD period, and recovery night –separated by at least 2 weeks each. Two of the sessions were preceded by a week of sleep extension (12h nightly sleep opportunities), while one session was preceded by a week of sleep restriction (6h nightly sleep opportunities), in randomized, counterbalanced order; only the sleep extension sessions are used here. Prior to the experiment, subjects filled out the Eysenck Personality Questionnaire (EPQ), which yielded an extraversion score; one subject did not complete the questionnaire and was excluded from analyses. Every 2h during TSD, subjects completed a 60min neurobehavioral test battery. At the beginning of the test battery, subjects completed the Karolinksa Sleepiness Scale (KSS) and visual analog scales of mood and fatigue (VAS-M and VAS-F). At the end of the test battery, subjects completed self-ratings of their performance (1–7 scale) and effort (1–4 scale). The relationship between extraversion and subjective scores after sleep deprivation (average over last 24h of 36h TSD period) relative to baseline (average over first 12h of TSD period) was analyzed using mixed-effects analysis of covariance, controlling for order, with a random effect over subjects on the intercept. Results No significant relationships were observed between extraversion and subjective estimates of sleepiness (KSS, p=0.45), fatigue (VAS-F, p=0.80), mood (VAS-M, p=0.14), performance (p=0.89), and effort (p=0.93). Conclusion These results indicate that extraversion is not a reliable predictor of trait-like individual differences in subjective vulnerability to 36h TSD. Support (if any) NASA grant NAG9-1161, CDMRP grant W81XWH-20-1-0442

Mental fatigue prediction during eye-typing.

Mental fatigue is a common problem associated with neurological disorders. Until now, there has not been a method to assess mental fatigue on a continuous scale. Camera-based eye-typing is commonly used for communication by people with severe neurological disorders. We designed a working memory-based eye-typing experiment with 18 healthy participants, and obtained eye-tracking and typing performance data in addition to their subjective scores on perceived effort for every sentence typed and mental fatigue, to create a model of mental fatigue for eye-typing. The features of the model were the eye-based blink frequency, eye height and baseline-related pupil diameter. We predicted subjective ratings of mental fatigue on a six-point Likert scale, using random forest regression, with 22% lower mean absolute error than using simulations. When additionally including task difficulty (i.e. the difficulty of the sentences typed) as a feature, the variance explained by the model increased by 9%. This indicates that task difficulty plays an important role in modelling mental fatigue. The results demonstrate the feasibility of objective and non-intrusive measurement of fatigue on a continuous scale.