Concept of time-on-task induced fatigue in lay people: a survey-based examination using situational judgement paradigm

A variety of studies suggest mental fatigue (MF) negatively influences both perceptions of physical fatigue and psychomotor performance. No prior investigation has examined potential changes in player ratings of MF over the course of an English Premier League (EPL) season. This study analysed how MF and PF varied among elite footballers, at both grouped and individual levels, across a 46 match EPL season. Prospective cohort study. Over the course of a 40-week, 151 training sessions and 46 games season, 21 first team male EPL footballers rated both physical fatigue (PF) and MF on a 100-mm visual analogue scale on match day minus-one (M-1). No significant group differences were established for MF (18.9 ± 13.0 vs. 17.8 ± 14.8 vs. 20.8 ± 20.5) and PF (21.4 ± 14.0 vs. 20.9 ± 14.7 vs. 19.9 ± 17.5) (P > 0.05) between early, mid and late season timepoints. However, pervasive individual differences were evident across timescales. Unlike earlier comparable work in netball, this study did not detect group-based changes in MF or PF over a competitive season. However, extensive changes in individual ratings of MF and PF did occur. This study highlights the potential importance of monitoring and managing MF trends within squads of elite footballers. The 100-mm visual analogue scale provides practitioners with a pragmatic tool capable of, in a resource-efficient manner, monitoring MF in EPL squads. Monitoring MF potentially facilitates the customised provision of targeted remediation strategies encompassing (a) training design, (b) individualized recovery and (c) player education relating to MF alleviation and stress management interventions.

The present study aimed to assess the perception and change of mental and physical fatigue and to examine acute effects of mental recovery strategies in air rifle athletes across simulated competition days with two consecutive competition bouts. We conducted a randomized counterbalanced crossover study. 22 development air rifle athletes (Mage = 17.77 ± 4.0) of a regional squad participate in the study. The Short Recovery and Stress Scale (SRSS), perception of mental fatigue, physical fatigue, concentration and motivation as well as differential Ratings of Perceived Exertion (RPE) were used to assess recovery-stress states and fatigue states. During a recovery break, participants underwent two mental recovery strategies (powernap, systematic breathing) or a control condition. Total shooting scores were recorded for both competition bouts. Study results revealed a significant increase of post ratings for mental (p < .001) and physical fatigue (p < .001) for both competition bouts. The correlation coefficient between change in mental and physical fatigue for both competitions revealed a shared variance of 7.9% and 18.6%, respectively. No significant group-based acute effects of the use of mental recovery strategies on shooting performance, and psychological and perceptual measures were found. On an individual level, results illustrated statistical relevant improvements of shooting performance after powernapping or systematic breathing. Mental and physical fatigue increased and accumulated across a simulated air rifle competition and mental fatigue emerged as a separate construct from physical fatigue. The use of strategies to accelerate mental recovery on an individual level (e.g., powernap, systematic breathing) may be a first step to manage a state of mental fatigue, but further studies on mental recovery strategies in an applied setting are needed.

HighlightsWhat are the main findings?Mental fatigue significantly impaired archery shooting performance and increased perceived exertion and mental effort despite no changes in heart rate.Mental fatigue alters mood states (increased anger and fatigue) and reduces enjoyment, indicating a strong psychophysiological impact without parallel physiological responses.What are the implications of the main findings?Mental fatigue primarily affects perceptual-cognitive and affective processes rather than physiological load in closed-skill sports such as archery.Monitoring and managing mental fatigue should be prioritized in precision sports, as performance decrements may occur independently of traditional physiological markers.Background/Objective: Mental fatigue (MF) significantly impairs psychomotor performance in dynamic sports; however, its specific impact on closed-skill precision-demanding tasks remains underexplored. This study investigated the acute effects of experimentally induced MF exposure on psychophysiological responses, mood states, and archery shooting performance. Methods: Fifteen well-trained male compound-bow archers participated in a randomized crossover study. Participants completed an MF condition (30 min modified Stroop task) and a control condition (CON; passive viewing of a neutral documentary), separated by a 72 h washout period. Continuous heart rate (HR), archery shooting accuracy, ratings of perceived exertion (RPE), rating scale of mental effort (RSME), state anxiety (VAS-A), mood states, and exercise enjoyment scale (EES) were assessed. Results: The Stroop task successfully induced subjective MF. Consequently, shooting accuracy significantly deteriorated in the MF condition compared to that in the CON condition (p < 0.001; g = 0.731). While HR and VAS-A remained consistent across conditions, the MF condition elicited a significant increase in RPE (p = 0.007; g = 0.836) and RSME (p = 0.010; g = 0.794). Furthermore, MF significantly increased feelings of anger and fatigue while drastically reducing PACES (p < 0.001; g = 1.530). Conclusions: Acute MF significantly degrades fine motor accuracy in precision sports. The pronounced dissociation between elevated RPE and stable peripheral physiological strain suggests that performance decline is driven by top-down cognitive burden rather than physiological limitations. Therefore, systematic monitoring of cognitive load is crucial for optimizing performance in precision sports.

Objective The purpose of this study was to identify potential phenotypic and biological factors that relate to directional changes in subjective feelings of mental and physical energy and fatigue during exercise-heat stress. Methods Fifteen subjects (female = 6; 29 ± 9 years; 71 ± 14 kg) completed 90 min of cycling in the heat with (euhydration) or without fluid (dehydration). Subjective feelings of mental and physical energy and fatigue were measured using visual analog scales, and subjects were bifurcated based on the directionality of mood. Changes in mood were correlated with baseline phenotypic characteristics and biofluid composition. Results Subjective feelings of mental (median change: 60.5 (hypohydrated) vs. 18.0 (euhydrated), p = 0.03) and physical fatigue (77.0 (hypohydrated) vs. 57.0 (euhydrated), p < 0.01) were greater post-exercise with dehydration, while feelings of mental (−27.0 (hypohydrated) vs. −18.5 (euhydrated), p = 0.17) and physical energy (−47.0 (hypohydrated) vs. −44.0 (euhydrated), p = 0.39) were not different compared to euhydration. Higher body mass index (p = 0.07), fat-free mass (0.03), and a more coordinated cardiorespiratory system (p < 0.01) were related to a decrease in mental energy and increased mental fatigue. Changes in blood carbon dioxide (p = 0.02) were greater in subjects who reported an increase in mental energy, while subjects who reported an increase in mental fatigue had lower decreases in blood chloride (p = 0.04). Subjects who reported an increased physical energy had a lower decrease in hemoglobin (p = 0.04). Conclusions Our findings support previous work suggesting baseline characteristics and blood biomarkers may be associated with mood states.

Combating mental fatigue in soldiers

The purpose was to test whether a single dose of black pepper or rosemary produced short-term enhancements in sustained attention, motivation to perform cognitive tasks, or feelings of mental energy and fatigue. Outcomes were measured in 40 young adults with below average feelings of energy before and twice after they orally consumed capsules containing either black pepper (2.0 g), rosemary (1.7 g), or a placebo (3.1 g rice flour). Sustained attention was measured using a 16-min dual task, in which, single-digit numbers were presented every second on a screen and the participant performed both a primary task [detection of three successive, different odd digits] and a secondary task [detection of the number 6]. Feelings of energy and fatigue were measured using the vigor and fatigue subscales of the Profile of Mood States and visual analog scales (VAS). Analysis of variance showed nonsignificant condition (spice versus placebo)×time (T1, T2, & T3) effects for motivation, measured with a VAS, and the intensity of energy and fatigue feelings. Unadjusted effect sizes revealed that rosemary induced small, transient reductions in false alarm errors (d=0.21) and mental fatigue (d=0.40) at isolated time periods. Time-varying analysis of covariance, controlling for motivation to perform cognitive tasks, showed no significant effects on the primary or secondary task outcomes of correct responses (hits), errors (false alarms, misses), speed of response (reaction time), and signal detection sensitivity. It is concluded that black pepper and rosemary, consumed in a capsule form, in the doses used and while wearing a nose clip to block olfactory effects, do not induce consistent short-term improvements in sustained attention, motivation to perform cognitive tasks, or feelings of mental energy and fatigue in young adults with low energy.

The aim of the study was to analyze the effect of aerobic exercise with different levels of blood flow restriction pressure on mood in military personnel. The sample consisted of 13 military men (age = 20.6 ± 2.2 years; body mass = 68.1 ± 7.7 kg; height = 1.69 ± 0.05 cm). The walking protocols with and without BFR were carried out over 18 minutes, as follows: a) CW+50%BFR - continuous treadmill walking (40% vVO2max) with 50% BFR; b) CW= continuous treadmill walking without BFR (40% vVO2max); c) CW+80%BFR= continuous treadmill walking (40% of vVO2max) with 80% BFR and d) CW+100%BFR= continuous treadmill walking (40% of vVO2max) with 100%BFR. Mood was measured using the Brunel scale (BRUMS) before exercise, immediately after exercise, 30 and 60 minutes after exercise. There was a significant reduction in the perception of vigor in the exercise protocols with BFR greater than in the CW protocol without BFR immediately after exercise (p&lt; 0.05); b) there was a significant reduction in the perception of vigor up to 60 minutes in the exercise protocols with BFR (p&lt; 0.005); c) there were significant increases in the perception of fatigue in the exercise protocols with BFR immediately after exercise (p&lt; 0.005). We conclude that AE with different levels of BFR increases the perception of muscle fatigue and pain/discomfort immediately post-exercise, and sustains a reduction in the perception of vigor up to 60 minutes post-exercise when compared to the effects perceived with aerobic exercise without BFR. Keywords: Physical exercise, Military, Mood state, Aerobic training, Perceptual Skills.

Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity that affects many aspects of daily life. Two weeks of L-histidine daily ingestion in humans significantly improves mood states compared with a placebo; however, the effects of a single dose are unknown. We aimed to assess the effects of a single dose of L-histidine on mood states, including fatigue, in healthy men and women who regularly experienced fatigue and sleep deprivation. Participants were randomly assigned to the L-histidine or placebo group. They were provided a workload using the Uchida-Kraepelin Performance test, their mood states before and after the workload were assessed, and performance on mental tasks was measured. In the all participants analysis set, the results did not show superiority of the L-histidine group over the placebo group for all endpoints. However, in the subgroup with high fatigue levels, the L-histidine group showed significant decreases compared with the placebo group in the changes in fatigue-inertia (FI), confusion-bewilderment (CB), depression-dejection (DD), and total mood disturbance (TMD) T-scores and a significant increase in the change in vigor-activity (VA) T-score (p = 0.022, 0.049, 0.039, 0.036, and 0.023, respectively). Although a single ingestion of L-histidine showed no significant improvements in any of the endpoints compared with the placebo in the prespecified all-participants analysis set, the exploratory findings suggest that it may alleviate negative mood states, including fatigue, confusion, and depression, and may also improve vigor after a workload in humans with high fatigue levels. Clinical Trial Registry number: UMIN000055719.

Work and intellectually fatiguing environments can significantly influence the health of individuals, which is strictly bound to motor efficiency. In particular, desk workers and university students may have a sedentary lifestyle and a condition of mental fatigue caused by daily routine, which could impair motor efficiency. The assessment is a starting point for enhancing awareness of the individual's psychophysical condition through the perception of one's body motor efficiency, motivating to move towards improvement. This way, a submaximal test based on perceived exertion was developed (Cubo Fitness Test, CFT) and validated in previous studies. Hence, two further studies were employed to enhance the consistency and accuracy of this instrument in different conditions. The first study investigated the internal responsiveness of CFT, evaluating if mental fatigue could affect motor efficiency. The second study investigated which perceived intensity (weak, moderate, strong, or absolute maximum) could be more reliable for applying the CFT (as previous research focused the investigation only on moderate intensity). In the first investigation, participants assessed two stimuli (mental fatigue induced with a Stroop color-word task and a neutral condition based on the vision of a documentary) lasting 60 min each. The quality of psychophysical recovery (total quality recovery) and the mood state (Italian Mood State questionnaire) were evaluated before the stimuli. After the fatiguing or the neutral task, the mood state was newly assessed, together with the evaluation of the workload's characteristics (Nasa TLX) and the CFT motor efficiency. In the second investigation, participants had to perform CFT twice for each at different intensities of Borg's Scale of perceived exertion. Researchers successfully requested to fill out the NASA TLX questionnaire regarding the perceived workload characteristics of CFT, and the reliability of each intensity was assessed. Results seem to enhance the consistency and the accuracy of the instrument. Indeed, findings evidenced that CFT is not influenced by mental fatigue conditions typical of the intellectual work of desk workers and university students for which this test was specifically conceived. Moreover, moderate and strong perceived intensity are the most adequate conditions to assess motor efficiency in these populations.

Individuals experience mental fatigue during or after prolonged periods of cognitive activity. The aim of the present study was to investigate the effect of mental fatigue on detection of changes at the preattentive stage in the visual system by recording visual mismatch negativity of event-related potential components. Twenty-four students who volunteered for the study were divided randomly into either a mental fatigue group or a control group. Participants in the mental fatigue group were asked to perform an AX continued practice test for 2.5 h while the control group rested in the lab for 2.5 h. Then, subjective fatigue and mood state were measured by the Subjective Fatigue Symptom Questionnaire and the Profile of Mood States, respectively. Preattentive processing was evaluated as well by assessing the duration of the passive oddball task both before and after manipulation. In participants who performed the AX continued practice test, we observed a significant increase in feelings of fatigue and tiredness, and negative emotion. In these same participants, we observed a significant decrease in attention and positive emotion. This indicates that continuous cognitive operation induces mental fatigue. In addition, we found that the visual mismatch negativity amplitude was significantly reduced in participants with mental fatigue, implying that visual deviant/change detection is affected by mental fatigue. These results suggest that preattentive change detection and automatic processing decline as a result of mental fatigue.

The effect of histidine on mental fatigue and cognitive performance in subjects with high fatigue and sleep disruption scores

To examine the effects of caffeine ingestion on physiological and perceptual responses in mentally fatigued individuals. Eight male physically active subjects completed four cycling constant-workload tests in four experimental conditions at 80% of maximal power output: control (C), mental fatigue (MF), mental fatigue plus caffeine ingestion (5mg/kg) (MF-CAF), and mental fatigue plus placebo (MF-PLA). The mental fatigue was induced by a continuous performance task A-X version (AX-CPT). Before and after the AX-CPT, the profile of mood state (POMS) and blood samples for lactate measurement were collected. Oxygen consumption ([Formula: see text]), rating of perceived exertion (RPE), and electromyography (EMG) activity were measured during the cycling test. The time to exhaustion in C, MF, MF-PLA, and MF-CAF were 251±30, 222±23, 248±28, and 285±42s, respectively. Delta values (corrected by C condition) were higher in MF-CAF than MF (P=0.031). MF-CAF reported higher Vigor scores when compared with C (P=0.046) and MF (P=0.020). RPE at the first minute was significantly higher in MF-PLA than in C (P=0.050); at the second minute, RPE was higher in MF-PLA than in C (P=0.049) and MF-CAF (P=0.048). EMG activity was not different between the conditions. Caffeine ingestion increased approximately 14% endurance performance after the induction of mental fatigue. This effect was accompanied by a tendency to improvement in mood state (i.e., vigor). Therefore, caffeine ingestion can promote a beneficial effect on endurance performance in mentally fatigued individuals.

Mental 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.

Fatigue, long recognized as a limiting factor in physical performance, has traditionally been conceptualized as comprising both objective (performance fatigability) and subjective (perception of fatigue) dimensions. In sports science, increasing attention has been paid to "mental fatigue", a state induced by mental efforts, owing to its presumed negative effects on subsequent physical performance. However, this opinion paper argues that the dominant focus on mental fatigue as a singular construct is overly narrow and potentially misleading. Many studies rely on mental tasks (e.g., Stroop test) to induce mental fatigue, assuming that a decline in task performance or self-reported fatigue only equates to mental fatigue. Yet such declines are neither universal nor easily attributable solely to fatigue. Factors such as boredom, mind-wandering, motivation, task automation, and affective states also influence performance and perception during mental tasks. Our research demonstrates that subjective experience during mental tasks is dynamic and multidimensional, with performance decrement and perceived fatigue varying widely across individuals and time. We advocate for a shift from the mental fatigue paradigm to a broader framework, which more accurately captures the interplay between cognitive demands and subjective states. Using tools such as the Temporal Experience Tracing (TET) method, we highlight the complex array of responses during mental tasks that go beyond fatigue alone. In doing so, we challenge current assumptions and call for more nuanced methodologies to assess how mental states affect subsequent physical performance.

The present study aimed to investigate the effects of matured hop bitter acids (MHBAs) on human cognition, mental fatigue, and mood state. In this randomized double-blind placebo-controlled study, 60 healthy adults (age 45-64 years) with self-awareness of cognitive decline were randomly divided into 2 groups and received either orally administered MHBAs (35 mg/day) or placebo for 12 weeks. Cognitive functions and mental states were assessed using neuropsychological tests or questionnaires at baseline and weeks 6 and 12 of the intervention. The change in verbal fluency score at week 6 compared with that at baseline was significantly higher in the MHBAs-treated group compared with that in the placebo group (P = 0.034), and Stroop test score at week 12 was significantly lower in the MHBAs-treated group compared with the placebo group (P = 0.019). Furthermore, subjective fatigue and anxiety at week 12 were significantly improved in the MHBAs-treated group (P = 0.008 and 0.043, respectively) compared with the placebo group. This is the first study to evaluate the effects of bitter ingredients in beer on cognition, subjective mood, and mental fatigue in a clinical trial. Our findings suggest that hop-derived bitter acids might be beneficial for cognition and mood state.