Subjective Fatigue Level Research Articles

Depression and sedentary behaviour in women with multiple sclerosis

Depression affects around 50% of people with Multiple Sclerosis (pwMS) during their lifetime. PwMS are typically less physically active and spend twice as much time engaging in sedentary behaviour compared to the general population. Therefore, a better understanding of the factors associated with depression in pwMS, as well as the relationship between depression and sedentary behaviour and physical activity, is crucial for developing effective therapeutic strategies MS treatment. This study aimed to investigate whether the presence of depressive symptoms in pwMS is related to a longer duration of sedentary behaviour. Specially, the study assessed the relationship between depression and sedentary behaviour in women with relapsing-remitting MS (RRMS). The sample for this cross-sectional study consisted of 78 women, including 38 with relapsing-remitting MS (RRMS) (EDSS 1 to 3) and 40 healthy women. The study evaluated the depression and time in sedentary behaviour, levels of physical activity and subjective fatigue in three groups: women without MS (CG), women with MS and depression (MSD), and women with MS without depression (MSND). We found significant differences in sedentary behaviour time when comparing the group of women with MS to the group with MS and depression. The logistic regression analysis presents depression as a factor associated with sedentary behaviour in women with MS. This association became even stronger after adjustment in the multivariate model (odds ratio=1.62; 95% CI (1.13-2.64); p=0.021). Despite no differences in clinical disabilities (EDSS) or physical activity levels between the two MS subgroups (MSD and MSND), we observed a longer duration of sedentary behaviour among participants with MS and depression. There was no association with the level of physical activity. This suggests a relationship between depression and sedentary behaviour in women with MS, independent of the level of physical activity. Prolonged sedentary behaviour is a risk factor for other comorbidities, including cardiovascular disease, highlighting the importance of addressing both depression and sedentary behaviour in the management of MS. Studies that examine the amount of time pwMS spend in sedentary behaviour in various countries are crucial for developing more effective strategies tailored to different ethnicities and cultures.

The Impact of Physiological and Psychological Fatigue on Work Efficiency: A Case Study of Parcel Sorting Work.

The popularity of online shopping in China has increased significantly, creating new development opportunities for the express delivery industry. However, the rapid expansion of the express industry has also created challenges in the parcel sorting process. The demanding nature of parcel sorting work, which is characterized by intense and prolonged repetitive tasks, makes individuals particularly vulnerable to the effects of fatigue. Fatigue is a complex condition that encompasses both physiological and psychological exhaustion. It often results in reduced energy levels and diminished functionality, significantly impacting an individual's performance at work and their overall well-being. This study aimed to investigate how physiological and psychological fatigue affects sorting efficiency and to identify appropriate rest periods that will allow employees to maintain their performance levels. The research involved fifteen participants who took part in a 60 min continuous sorting experiment and a similar experiment with scheduled breaks. During both trials, we collected data on participants' electromyography (EMG) and electrodermal activity (EDA), as well as subjective fatigue ratings (RPE). Signal features such as the median frequency (MF) of EMG and the skin conductance level (SCL) were analyzed to assess physiological and psychological fatigue, respectively. The results show that physiological fatigue mainly affects sorting efficiency in the first 30 min, while psychological fatigue becomes more influential in the following half-hour period. In addition, subjective fatigue levels during the first 30 min are primarily determined by psychological factors, while beyond that point, both physiological and psychological fatigue contribute to subjective fatigue. Rest periods of 415-460 s, based on EDA recovery times, effectively support sorting efficiency and participants' recovery. This study highlights the complex ways in which fatigue affects parcel sorting performance and provides valuable theoretical and practical insights for establishing labor quotas and optimizing work schedules in the parcel sorting industry.

Enhancing lower limb and core muscle activation with blood flow restriction training: a randomized crossover study on high-intensity squat exercises.

The primary objective of this study was to assess the impact of high-intensity deep squat training integrated with various blood flow restriction (BFR) modalities on the activation of lower limb and core muscles. A randomized, self-controlled crossover experimental design was employed with 12 participants. The exercise protocol consisted of squat training at 75% of one-repetition maximum (1RM), performed in 3 sets of 8 repetitions with a 2-min inter-set rest period. This was conducted under four distinct BFR conditions: continuous low BFR (T1), intermittent medium BFR (T2), intermittent high BFR (T3), and a non-restricted control (C). Surface electromyography (EMG) was utilized to collect EMG signals from the target muscles during the BFR and squat training sessions. The root mean square (RMS) amplitude standard values were calculated for each squat set to quantify muscle activation levels, with these values expressed as a percentage of the maximum voluntary contraction (%MVC). Rating of Perceived Exertion was evaluated after each squat set, and leg circumference measurements were taken. 1) During the first two sets of deep squats, the %MVC of the vastus lateralis and vastus medialis in all compression groups was significantly higher than that in the control group (p < 0.05). Furthermore, in the first set, the %MVC of the vastus lateralis in Group T3 was significantly higher than in Group T2 (p < 0.05). In the third set, the %MVC of the vastus medialis in Groups T1 and T3 was significantly lower than in the first two sets (p < 0.05). 2) Group T1 showed an increased activation of the biceps femoris and semitendinosus muscles in the second and third sets, with %MVC values significantly greater than in the first set (p < 0.05). Group T2 only showed an increase in biceps femoris activation in the third set (p < 0.05). Group T3 significantly increased the activation of the biceps femoris and semitendinosus muscles only in the first set (p < 0.05). 3) No significant differences were observed in the changes of rectus abdominis %MVC among the groups (p > 0.05). In the first set, Group T3's erector spinae %MVC was significantly higher than the control group's; in the second set, it was significantly higher than both Group T2 and the control group's (p < 0.05). 4) After training, a significant increase in thigh circumference was observed in all groups compared to before training (p < 0.05). 5) For RPE values, Group T2's post-squat values were significantly higher than the control group's after all three sets (p < 0.05). Group T1's RPE values were also significantly higher than the control group's after the third set (p < 0.05). Groups T1, T2, and C all had significantly higher RPE values in the second and third sets compared to the first set (p < 0.05). All BFR modalities significantly enhanced the activation level of the anterior thigh muscles, with the continuous low BFR mode demonstrating a more stable effect. No significant differences were found in the activation level of the rectus abdominis among the groups. However, the intermittent high BFR mode was the most effective in increasing the activation level of the erector spinae muscles. While BFR did not further augment leg circumference changes, it did elevate subjective fatigue levels. The RPE was lowest during squatting under the intermittent high BFR condition.

Probing sustained attention and fatigue across the lifespan.

Trait fatigues reflects tiredness that persists throughout a prolonged period, whereas state fatigue is a short-term reaction to intense or prolonged effort. We investigated the impact of sustained attention (using the SART) on both trait and state fatigue levels in the general population. An online version of the SART was undertaken by 115 participants, stratified across the whole adult lifespan. While pre-task trait fatigue was a strong indicator of the initial state fatigue levels, undergoing the task itself induced an increase in reported subjective state fatigue, and an accompanying reduction in subjective energy rating. Consistent with this finding, greater subjective state fatigue levels were associated with reduced accuracy. In addition, age was the best predictor of inter-participant accuracy (the older the participants, the greater the accuracy), and learning (i.e., task duration reducing reaction times). Moreover, a ceiling effect occurred where participants with higher trait fatigue did not experience greater state fatigue changes relative to those with low trait scores. In summary, we found improved accuracy in older adults, as well as a tight coupling between state fatigue and SART performance decline (in an online environment). The findings warrant further investigation into fatigue as a dynamic, task-dependent state and into SART performance as an objective measure and inducer of fatigue.

The Impact of Visual and Kinesthetic Motor Imagery on Mental Fatigue and Classification Performance in Untrained Participants

Motor imagery (MI) is a critical component of Brain-Computer Interface (BCI) technology, but the effective use of MI-BCI requires significant user training. In order to improve the training effect, it is necessary to choose a stable and easy to use paradigm. To explore the effects of different paradigms on training effectiveness, 18 untrained participants were recruited to perform kinesthetic motor imagery (KMI) and visual motor imagery (VMI) experiments. The participants’ subjective vividness and mental fatigue levels were measured using a subjective scale and (θ + α)/β value in the experiments, respectively. Additionally, the Common Spatial Pattern (CSP) algorithm and the Support Vector Machine (SVM) algorithm were used to extract EEG signal features and classify them. The results showed that the majority of participants demonstrated a greater aptitude for excelling in the VMI paradigm, where the average accuracy rate was 84.7%, compared to the KMI paradigm, where the average accuracy rate was 79.6%. In addition to this, participants with higher levels of sports proficiency showed better adaptability in the KMI paradigm. Compared to KMI, VMI can enable most inexperienced participants to achieve a better user experience with less fatigue and improve training performance.

Low blood glucose and fatigue accumulation at peak hours of occupational trauma in secondary industry workers

Objectives. The incidence of occupational traumatic injuries caused by human error has been reported to occur at 11:00 and 8–9 h after commencing work. Impaired attention is closely related to the incidence of these accidents. Therefore, this study aimed to clarify the changes in blood glucose, fatigue and stress response hormone levels over time among workers in a secondary industry. Methods. The blood glucose and subjective fatigue levels of 26 male secondary-industry workers were measured on workdays. In addition, the cortisol and dehydroepiandrosterone levels in saliva were measured on one workday and one holiday. Results. Blood glucose levels at 11:00 and 17:30 on the workday were significantly lower than those at 09:30. Moreover, hypoglycemia was observed in some participants. A significant increase in subjective fatigue levels was observed during the workday. However, no significant differences in salivary cortisol levels were observed between the workday and the holiday at any time point. Conclusions. Blood glucose levels decreased and subjective fatigue levels increased at the time points that occupational accidents were reported to occur most frequently during work. These factors may contribute to human errors due to impaired attentional function.

Decoding visual fatigue in a visual search task selectively manipulated via myopia-correcting lenses.

Visual fatigue resulting from sustained, high-workload visual activities can significantly impact task performance and general wellbeing. So far, however, little is known about the underlying brain networks of visual fatigue. This study aimed to identify such potential networks using a unique paradigm involving myopia-correcting lenses known to directly modulate subjectively-perceived fatigue levels. A sample of N = 31 myopia participants [right eye-SE: -3.77D (SD: 2.46); left eye-SE: -3.75D (SD: 2.45)] performed a demanding visual search task with varying difficulty levels, both with and without the lenses, while undergoing fMRI scanning. There were a total of 20 trials, after each of which participants rated the perceived difficulty and their subjective visual fatigue level. We used representational similarity analysis to decode brain regions associated with fatigue and difficulty, analyzing their individual and joint decoding pattern. Behavioral results showed correlations between fatigue and difficulty ratings and above all a significant reduction in fatigue levels when wearing the lenses. Imaging results implicated the cuneus, lingual gyrus, middle occipital gyrus (MOG), and declive for joint fatigue and difficulty decoding. Parts of the lingual gyrus were able to selectively decode perceived difficulty. Importantly, a broader network of visual and higher-level association areas showed exclusive decodability of fatigue (culmen, middle temporal gyrus (MTG), parahippocampal gyrus, precentral gyrus, and precuneus). Our findings enhance our understanding of processing within the context of visual search, attention, and mental workload and for the first time demonstrate that it is possible to decode subjectively-perceived visual fatigue during a challenging task from imaging data. Furthermore, the study underscores the potential of myopia-correcting lenses in investigating and modulating fatigue.

Non-pharmacological interventions for sleep disruptions and fatigue after traumatic brain injury: a scoping review.

The aim of this study was to conduct a scoping review to determine the nature, variety, and volume of empirical evidence on nonpharmacological interventions for sleep disturbances with potential implications for fatigue in adults sustaining a traumatic brain injury (TBI). A systematic literature search was conducted across four databases to identify primary studies testing a single non-pharmacological intervention or a combination of non-pharmacological interventions for sleep disturbances and fatigue in community-dwelling adults with TBI. Sixteen studies were reviewed addressing six non-pharmacological interventions for sleep disruptions and fatigue after TBI including light therapy, cognitive-behavioral therapy, warm footbath application, shiatsu, and sleep hygiene protocol. Non-pharmacological interventions involving light or cognitive-behavioral therapy were reported in 75% of the studies. Actigraphy-based estimation of total sleep time and subjective level of fatigue were frequent outcomes. While this scoping review has utility in describing existing non-pharmacological approaches to manage sleep and fatigue after TBI, the findings suggest that interventions are often developed without considering TBI individuals' source of motivation and the need for support in self-administration. Future studies may achieve greater sustainability by considering the evolving needs of TBI patients and their families and the drivers and barriers that might influence non-pharmacological intervention use at home.

Post-COVID fatigue: Reduced quality-of-life associated with clinically relevant fatigue in mild disease courses

ABSTRACT Fatigue is a pervasive symptom experienced by many individuals after COVID-19. Despite its widespread occurrence, fatigue remains a poorly understood and complex phenomenon. Our aim is to evaluate the subjective experience of mental fatigue after COVID-19 and to assess its significance for daily life functioning. In this online questionnaire study (N = 220), the Fatigue Severity Scale (FSS), World Health Organization Quality-of-Life assessment (WHOQoL) and a subjective severity rating of the COVID-19 disease progression were used. For our statistical analyses we utilized independent samples t-tests, one-way ANOVA with post-hoc analyses, and a multiple regression. As expected our findings revealed the COVID group reported significantly higher levels of subjective fatigue compared to the control group. Moreover, there was a significant difference between experienced fatigue across the four severity groups. Participants who had a milder course of disease also experienced severe subjective fatigue. Subjective fatigue explained 40% variance in quality-of-life. In conclusion, severe subjective fatigue appears to be associated with increased self-reported COVID-19 symptom severity and lower quality-of-life but is already observable in milder cases. This underscores, firstly, the importance of considering also less severe cases and, secondly, the need to develop rehabilitation and psychological interventions for fatigue.

Effect of Split Condition and Driving Duration on Fatigue Based on Changes in Brain Wave Signals when Driving a Train Simulator

One of the causes of train accidents is driver fatigue. Train driver fatigue can be caused by sleep factors, known as split sleep. This study aims to assess the impact of split sleep on train driver fatigue. A total of 12 male participants were asked to drive a train simulator for 2.5 hours after facing two sleep conditions, namely split sleep and baseline. The split sleep condition required participants to sleep in two segments at 05.00-10.00 and 12.00-15.00, while the baseline condition was conducted in one segment at 21.00-05.00. Fatigue was measured based on changes in brain wave signals via electroencephalogram (EEG) and Swedish Occupational Fatigue Inventory (SOFI). Fatigue measurements with EEG were conducted at the 10-minute start and end of the simulation, while fatigue measurements with SOFI were conducted before and after the simulation. The results of this study showed a higher level of subjective fatigue in split sleep compared to the baseline. However, the EEG signal change data and other dimensions of SOFI dimensions showed no difference between the two sleep states. Another result was an increase in fatigue after simulation in all dimensions of the SOFI. Therefore, split sleep should not be applied by drivers because it can increase subjective fatigue. However, if split sleep needs to be applied, it is necessary to fulfill sleep quantity (7-9 hours) and improve sleep quality. In addition, the company also needs to ensure that the train driver are awake at least 15 minutes.

Neuromuscular behaviour in the first dorsal interosseus following mental fatigue.

We examined sex-specific changes to neuromuscular function in response to mental fatigue. Twenty-five young, healthy adults (13 F, 12M) performed a mentally fatiguing task and control condition for 30min on two separate days. Neuromuscular function was assessed in the first dorsal interosseous before and after each condition. Reaction time decreased after the mentally fatiguing task (P<0.001, η2 =0.47). Males and females reported higher levels of subjective fatigue after the mentally fatiguing task (P<0.02, η2 =0.07). Motor unit firing rate increased over time at 10% maximal voluntary contraction (MVC; P<0.04, η2 =0.16), and decreased over time at 50% MVC (P<0.01, η2 =0.14); however, this was not unique to either sex. During a variable force contraction, error decreased in females over time and increased in males (P<0.05, η2 =0.13), although changes were not unique to mental fatigue. Physiological function of the neuromuscular system was not specifically affected by mental fatigue in males or females.

Acute Effects of Fatigue on Cardiac Autonomic Nervous Activity.

The onset of fatigue disrupts the functioning of the autonomic nervous system (ANS), potentially elevating the risk of life-threatening incidents and impairing daily performance. Previous studies mainly focused on physical fatigue (PF) and mental fatigue (MF) effects on the ANS, with limited knowledge concerning the influence of physical-mental fatigue (PMF) on ANS functionality. This study aimed to assess the immediate impact of PMF on ANS function and to compare its effects with those of PF and MF on ANS function. Thirty-six physically active college students (17 females) without burnout performed 60-min cycling exercises, AX-Continuous Performance Task (AX-CPT), and cycling combined with AX-CPT to induce PF, MF, and PMF respectively. Subjective fatigue levels were measured using the Rating of Perceived Exertion scale and the Visual Analog Scale-Fatigue. Heart rate variability was measured before and after each protocol to assess cardiac autonomic function. The proposed tasks successfully induced PF, MF, and PMF, demonstrated by significant changes in subjective fatigue levels. Compared with baseline, PMF decreased the root mean square of successive differences (RMSSD) between normal heartbeats (P < 0.001, d = 0.50), the standard deviation of normal-to-normal RR intervals (SDNN) (P < 0.01, d = 0.33), and the normalized high-frequency (nHF) power (P < 0.001, d = 0.32) while increased the normalized low-frequency (nLF) power (P < 0.001, d = 0.35) and the nLF/nHF ratio (P < 0.001, d = 0.40). Compared with MF, PMF significantly decreased RMSSD (P < 0.001, η2 = 0.431), SDNN (P < 0.001, η2 = 0.327), nLF (P < 0.01, η2 = 0.201), and nHF (P < 0.001, η2 = 0.377) but not the nLF/nHF ratio. There were no significant differences in ΔHRV (i.e., ΔRMSSD, ΔSDNN, ΔnLF/nHF, ΔnLF, and ΔnHF), heart rate, and training impulse between PF- and PMF-inducing protocols. Cognitive performance (i.e., accuracy) in AX-CPT during the PMF-inducing protocol was significantly lower than that during the MF-inducing protocol (P < 0.001, η2 = 0.101). PF and PMF increased sympathetic activity and decreased parasympathetic activity, while MF enhanced parasympathetic activity.

Assessing Flight Crew Fatigue under Extra Augmented Crew Schedule Using a Multimodality Approach

During the COVID-19 pandemic, the question of how to reduce the risk of viral infection for international airline pilots without increasing the risk of fatigue was a novel and urgent theoretical and practical problem, which had never been encountered in the world civil aviation industry. A new scheduling method implemented by the Civil Aviation Administration of China (CAAC) is the extra augmented crew (EAC) schedule, which avoids crew layover in another country on international flights by extending the maximum duty time and adding two additional crew members to such long-haul flights. In this study, a multi-day flight crew fatigue assessment was conducted to evaluate the impact of EAC flight. We recruited 71 pilots as participants, and their fatigue during EAC flights was measured using a multimodality approach integrating a subjective fatigue report, a psychomotor vigilance task, sleep monitoring, and biomathematical model predictions. The results showed that the subjective fatigue level increased during duty time compared to off-duty time, but still with acceptable levels of under 7, as measured by the Karolinska Sleepiness Scale; objective secondary task performance, as measured by the classic psychomotor vigilance task, showed no differences; pilots were able to get around 6 h of sleep, although they slept less during duty time compared to off-duty time. Model fitting using the FAID biomathematical model of fatigue confirmed that the EAC scheduling was compliant with the FAID tolerance level 91.3% of the time. The results suggest that the EAC flight created some moderate level of increased fatigue but no severe fatigue to cross-continent long-haul flight crews. This research can inform current and future scheduling and fatigue risk control during the pandemic or for future time-sensitive periods.

Physical and psychological recovery after vaginal childbirth with and without epidural analgesia: A prospective cohort study.

Enhanced recovery is the gold standard in modern perioperative management, including that for cesarean deliveries. However, qualitative and quantitative data on the physical and psychological recovery of women after vaginal childbirth are limited. Whether neuraxial labor analgesia influences postpartum recovery is unknown. Primiparous women anticipating a vaginal childbirth between January 2020 and May 2021 were enrolled. Women with major comorbidities or postpartum complications and those who underwent a cesarean delivery were excluded. Daily step count was measured using a wrist-worn activity tracker (FitbitTM Inspire HR) for 120 hours after vaginal childbirth. Subjective fatigue levels and health-related quality of life were assessed using the Multidimensional Fatigue Inventory (MFI) and EuroQol 5 Dimension 5 Level (EQ-5D-5L), respectively, at the 3rd trimester antenatal visit, on postpartum day 1 and 3, and at the one-month postpartum visit. Rest and dynamic pain scores and the location of pain were documented by participants during postpartum hospitalization. Among 300 women who were enrolled antenatally, 95 and 116 had a vaginal delivery without (NCB group) and with (EPL group) epidural analgesia, respectively. The median number of steps per 24 hours increased daily in both groups, and no significant difference was detected between the groups. Postpartum pain was mild overall, with median rest and dynamic pain scores being less than 4 and similar between the groups. MFI and EQ-5D-5L scores were the worst on postpartum day 1 in both groups and gradually improved to antepartum level by the one-month postpartum visit. Higher MFI score on postpartum day 1, but not the use of epidural analgesia, was associated with lower odds of achieving adequate postpartum ambulation (defined as >3500 steps between 48 and 72 hours postpartum). The use of epidural analgesia was not associated with worse recovery outcomes during postpartum hospitalization. UMIN-CTR, #UMIN000039343, registered on January 31, 2020.

Take a break: should breaks be enforced during digital breast tomosynthesis reading sessions?

ObjectivesDigital breast tomosynthesis (DBT) can improve diagnostic accuracy compared to 2D mammography, but DBT reporting is time-consuming and potentially more fatiguing. Changes in diagnostic accuracy and subjective and objective fatigue were evaluated over a DBT reporting session, and the impact of taking a reporting break was assessed.Materials and methodsForty-five National Health Service (NHS) mammography readers from 6 hospitals read a cancer-enriched set of 40 DBT cases whilst eye tracked in this prospective cohort study, from December 2020 to April 2022. Eye-blink metrics were assessed as objective fatigue measures. Twenty-one readers had a reporting break, 24 did not. Subjective fatigue questionnaires were completed before and after the session. Diagnostic accuracy and subjective and objective fatigue measures were compared between the cohorts using parametric and non-parametric significance testing.ResultsReaders had on average 10 years post-training breast screening experience and took just under 2 h (105.8 min) to report all cases. Readers without a break reported greater levels of subjective fatigue (44% vs. 33%, p = 0.04), which related to greater objective fatigue: an increased average blink duration (296 ms vs. 286 ms, p < 0.001) and a reduced eye-opening velocity (76 mm/s vs. 82 mm/s, p < 0.001). Objective fatigue increased as the trial progressed for the no break cohort only (ps < 0.001). No difference was identified in diagnostic accuracy between the groups (accuracy: 87% vs. 87%, p = 0.92).ConclusionsImplementing a break during a 2-h DBT reporting session resulted in lower levels of subjective and objective fatigue. Breaks did not impact diagnostic accuracy, which may be related to the extensive experience of the readers.Clinical relevance statementDBT is being incorporated into many mammography screening programmes. Recognising that reporting breaks are required when reading large volumes of DBT studies ensures this can be factored in when setting up reading sessions.Trial registrationClinical trials registration number: NCT03733106Key Points• Use of digital breast tomosynthesis (DBT) in breast screening programmes can cause significant reader fatigue.• The effectiveness of incorporating reading breaks into DBT reporting sessions, to reduce mammography reader fatigue, was investigated using eye tracking.• Integrating breaks into DBT reporting sessions reduced reader fatigue; however, diagnostic accuracy was unaffected.

Identification and Classification of Physical Fatigue in Construction Workers Using Linear and Nonlinear Heart Rate Variability Measurements

Several studies have analyzed heart rate variability (HRV) using nonlinear methods, such as approximate entropy, the largest Lyapunov exponent, and correlation dimension in patients with cardiovascular disorders. However, few studies have used nonlinear methods to analyze HRV in order to determine the level of physical fatigue experienced by construction workers. As a result, to identify and categorize physical fatigue in construction workers, the current study examined the linear and nonlinear approaches of HRV analysis. Fifteen healthy construction workers (mean age, 33.2±6.9 years) were selected for this study. A textile-based wearable sensor monitored each participant’s HRV after they completed 60 min of bar bending and fixing tasks. At baseline, 15, 30, 45, and 60 min into the task, participants were given the Borg-20 to measure their subjective levels of physical fatigue. Nonlinear [e.g., R-R interval (RRI) variability, entropy, detrended fluctuation analysis] and linear (e.g., time- and frequency-domain) HRV parameters were extracted. Five machine learning classifiers were used to identify and discern different physical fatigue levels. The accuracy and validity of the classifier models were evaluated using 10-fold cross-validation. The classification models were developed by either combining or individualized HRV features derived from linear and nonlinear HRV analyses. In the individualized feature sets, time-domain features had the highest classification accuracy (92%) based on the random forest (RF) classifier. The combined feature (i.e., the time-domain and nonlinear features) sets showed the highest classification accuracy (93.5%) using the RF classifier. In conclusion, this study showed that both linear and nonlinear HRV analyses can be used to detect and classify physical fatigue in construction workers. This research offers important contributions to the industry by analyzing the variations in linear and nonlinear HRV parameters in response to construction tasks. This study demonstrates that HRV values changed significantly in response to physical work, indicating a change in the relative activity of cardiac autonomic functions as a result of fatigue. Using the ways in which HRV parameters vary in response to increased workloads provides a sensitive marker for contrasting construction workers with and without cardiovascular disease. It also allows the site manager to track how quickly workers fatigue, so that they can switch up their workload to reduce the likelihood that any one worker would get severely exhausted, or to suggest that workers who are already severely fatigued take a break to prevent further injury.

A hypoarousal model of neurological post-COVID syndrome: the relation between mental fatigue, the level of central nervous activation and cognitive processing speed

BackgroundKnowledge on the nature of post-COVID neurological sequelae often manifesting as cognitive dysfunction and fatigue is still unsatisfactory.ObjectivesWe assumed that cognitive dysfunction and fatigue in post-COVID syndrome are critically linked via hypoarousal of the brain. Thus, we assessed whether tonic alertness as a neurocognitive index of arousal is reduced in these patients and how this relates to the level of central nervous activation and subjective mental fatigue as further indices of arousal.Methods40 post-COVID patients with subjective cognitive dysfunction and 40 matched healthy controls underwent a whole-report paradigm of briefly presented letter arrays. Based on report performance and computational modelling according to the theory of visual attention, the parameter visual processing speed (VPS) was quantified as a proxy of tonic alertness. Pupillary unrest was assessed as a measure of central nervous activation. The Fatigue Assessment Scale was applied to assess subjective mental fatigue using the corresponding subscale.ResultsVPS was reduced in post-COVID patients compared to controls (p = 0.005). In these patients, pupillary unrest (p = 0.029) and mental fatigue (p = 0.001) predicted VPS, explaining 34% of the variance and yielding a large effect with f2 = 0.51.ConclusionIn post-COVID patients with subjective cognitive dysfunction, hypoarousal of the brain is reflected in decreased processing speed which is explained by a reduced level of central nervous activation and a higher level of mental fatigue. In turn, reduced processing speed objectifies mental fatigue as a core subjective clinical complaint in post-COVID patients.

Psychological changes in athletes infected with Omicron after return to training: fatigue, sleep, and mood.

This study aims to analyze the changes of approximately 1 month in fatigue, sleep, and mood in athletes after returning to training following infection with the COVID-19 Omicron strain and provide recommendations for returning to training after infection. Two hundred and thirty professional athletes who had returned to training after being infected with COVID-19 in December 2022 were recruited to participate in three tests conducted from early January 2023. The second test was completed approximately 1 week after the first, and the third was completed about 2 weeks after the second. Each test consisted of completing scales and the exercise-induced fatigue measure. The scales included a visual analog scale, the Athens Insomnia Scale for non-clinical application, and the Depression-Anxiety-Stress scale. The exercise task was a six-minute stair climb test, and athletes evaluated subjective fatigue levels before and after exercise using another Visual Analog Scale and the Karolinska Sleepiness Scale. After returning to training, athletes' physical fatigue decreased initially but increased as training progressed. Cognitive fatigue did not change significantly. The exercise task led to elevated levels of physical fatigue after a longer duration of training. Sleep quality problems decreased rapidly after the start of training but remained stable with prolonged training. Depression levels continued to decline, while anxiety levels only reduced after a longer duration of training. Stress levels decreased rapidly after the start of training but did not change with prolonged training. Athletes who return to training after recovering from COVID-19 experience positive effects on their fatigue, sleep, and mood. It is important to prioritize anxiety assessment and interventions during the short period after returning and to continue monitoring fatigue levels and implementing recovery interventions over a longer period of time.

Effects of prolonged brisk walking induced lower limb muscle fatigue on the changes of gait parameters in older adults

BackgroundLower extremity muscle fatigue affects gait stability and increases the probability of injuries in the elderly. Research questionHow does prolonged walking-induced fatigue affect lower limb muscle activity, plantar pressure distribution, and tripping risk? MethodsEighteen elderly adults walked fast on a treadmill for 60 minutes at a fixed speed. The plantar pressure was measured with an in-shoe monitoring system, eight lower limb muscles were monitored using surface electromyography, and foot movements were tracked by a motion capture analysis system. The above data and participants’ subjective fatigue level feedback were collected every 5 minutes. Statistical analysis used the Friedman one-way repeated measures analysis of variance by ranks test followed by Wilcoxon signed-ranks test with Benjamini-Hochberg stepwise correction. ResultsThe subjective reported fatigue on the Borg scale increased gradually from 1 to 6 (p = 0.001) during the 60 minutes, while the EMG amplitude of vastus medialis significant decreased (p = 0.013). The results of plantar pressure demonstrated that the distribution of load and impulse shifted medially in both the heel and arch regions while shifted laterally in both the toes and metatarsal regions. The significantly increased contact area supports this shift at the medial arch (p = 0.036, increased by 6.94%, the 60th minute vs. the baseline). The symmetry of medial-lateral plantar force increased at the toes, metatarsal, and arch regions. The significantly increased parameters also include the swing time and contact time. The minimum foot clearance was reduced, increasing tripping probability, not significantly, though. SignificanceThis study facilitates a better understanding of changes in lower limb muscle activity and gait parameters during prolonged fast walking. Besides, this study has good guiding significance for developing smart devices based on plantar force, inertial measurement units, and EMG sensors to monitor changes in muscle activation in real-time and prevent tripping.

Physiological and Behavioral Changes of Passive Fatigue on Drivers during On-Road Driving

Driver fatigue can be further categorized into passive fatigue and active fatigue based on the task-induced fatigue perspective, with its categorization necessary from a theoretical basis and practical needs. Passive fatigue is caused by mental underload and inactive task engagement, which is considered more hazardous. To facilitate the construction of the driver monitoring system (DMS), the current study aims to investigate the physiological and behavioral changes of passive fatigue. A total of thirty-six participants completed a 90 min driving task on a monotonous highway, during which subjective fatigue level, eye tracking indicators, and driving dynamics were recorded using the Stanford Sleepiness Scale, Smart Eye Pro, and CAN Bus system. Results showed that drivers reported higher levels of fatigue as driving duration increased. An increase in pupil diameters and gaze dispersions were observed during the task. Drivers gradually reduced the control of the vehicle, in which faster speed and lower speed compliance were witnessed. In addition, a compensatory process was found as passive fatigue increased. Drivers tended to lower their standards to maintain the lateral position but recovered their lateral control when they lost control of the car speed. The current study emphasizes the importance of investigating active and passive fatigue of drivers independently, and the unique physiological and behavioral changes accompanied by passive fatigue should be considered in designing driver monitoring systems.