Effects Of Fatigue Research Articles

Impact of exercise on outcomes among Chinese patients with Crohn’s disease: a mixed methods study based on social media and the real world

ObjectiveThe effects of exercise on the health of people with Crohn’s disease (CD) remain unclear. This study aimed to explore the perspective of Chinese CD patients on exercise and the quantitative relationship between exercise and patient-reported outcomes.MethodsThis study used a mixed methods design consisting of three components. (1) Big data were mined from social media, and latent Dirichlet allocation (LDA) was used to perform cluster analysis on topics related to physical exercise. (2) A seven-step Colaizzi process was used to conduct semistructured interviews to obtain in-depth information about exercise. (3) A cross-sectional study was performed to examine this relationship using the Global Physical Activity Questionnaire (GPAQ) and Patient-reported Outcome Measurement Information System (PROMIS).ResultsLDA yielded a total of 1536 exercise-related posts; eight topics concerning CD patients were obtained through clustering (peer support, exercise therapy, diet, fatigue, exercise type, intestinal symptoms, body constitution and mental health), and 11 patients were interviewed to validate the results of LDA and explore the insight of Chinese CD. We identified two themes: the effects of exercise on people with CD and factors that promote and hinder exercise. A total of 119 patients with CD were surveyed. Considering confounding factors such as disease activity and medication, moderate-intensity recreational PA increased patients’ physical function and improved anxiety, depression, fatigue, pain intensity, and pain impact (all p < 0.05). In contrast, high-intensity work may lead to anxiety, depression, fatigue, pain, and pain effects (all p < 0.001). In addition, sedentary behaviour may lead to depression (p = 0.006).ConclusionPatients with CD tend to seek guidance on exercise through social media, and they generally believe that exercise is beneficial, especially for their psychological and spiritual health, despite difficulties in exercising. Physical activity may be an important factor affecting patients’ psychological health.Lay summaryCrohn’s disease has a profound impact on mental and emotional health, reducing patients’ quality of life. Exercise is a good habit that can enhance mental, emotional and social health, but there is currently no standard exercise program for patients with Crohn’s disease. The exercise experience of Chinese patients with Crohn’s disease can be helpful in formulating exercise plans.

Effect of acute fatigue on force generation accuracy and repeatability in youth athletes

The study aimed to evaluate the acute effect of the incremental running test on the accuracy and repeatability of submaximal force generation in adolescent athletes (biathletes and runners) with different training regimes. The isometric force generation was assessed in biathletes and runners by examining left and right elbow extension (LEE; REE); flexion (LEF; REF); left and right knee extensions (LKE; RKE) before and after the test. The mean force of 10 sub-maximal targeted force pulses (Fmean) and force variability parameters: standard deviation and coefficient variation were used for accuracy and repeatability estimation. Biathletes generated forces more accurate and exhibit better repeatability of produced forces than runners. Mean force measured in fatigue conditions, for both groups, did not vary significantly from rest measurements. Before testing biathletes exhibited significantly lower REE and LEE, and after testing lower REF and LEF variability than runners. After testing there was a significant drop of variability in elbows flexion but not extension and RKE in biathletes. Insignificant downward trend of variability parameters were found in runners. The presented findings corroborate sport-specific force generation ability alteration in response to exhaustive effort. Tracking force generation over time may be useful in the monitoring of training loads and specific training adaptations.

Effects of Resistance Exercise Combined with Cognitive Intervention Therapy on Cognitive Decline: A Randomized Controlled Trial of a Cognitively Declining Elderly Population.

Objective: To design a randomized controlled trial combining resistance exercise and cognitive intervention to carry out a dual-task computer-aided product design that combines hardware and software to explore the effects of different intensities of resistance exercise on cognitive function in elderly individuals with cognitive decline. Materials and Methods: Forty-eight participants (aged between 60 and 75 years) who satisfied the specified criteria were randomly assigned to one of four groups as follows: control (n = 12), low intensity (n = 12), medium intensity (n = 12), and high intensity (n = 12). The control group exclusively underwent cognitive training, whereas the experimental group underwent dual-task training at varying resistance exercise intensities. The main outcomes were short-term effects on cognitive function and lower limb strength using the Montreal Cognitive Assessment (MoCA), One-Rep Max (1RM) data, and training scores. The secondary outcomes were the effects of the participants' subjective fatigue and the system availability of the product. Results: The experimental group subjected to medium-intensity exercise exhibited the most substantial improvement in MoCA score (P = 0.017). All the groups achieved training scores that were substantially higher than the initial data (P < 0.05), and significant 1RM values were obtained for the left and right legs in the middle- and high-strength groups (P < 0.05). In addition, the participants indicated a positive experience with the application. Conclusions: Overall, we found support for the feasibility and acceptability of the product developed by dual-task therapy based on resistance exercise combined with cognitive intervention and showed the initial impact prospect of moderate-intensity resistance exercise. Future applications should be replicated in older individuals with Clinical trial registration: NCT06220565 Ethical approval: H2022013I decline.

Digital Fatigue and its Effects on Mental Health: Delphi and Multiple Linear Regression Analysis

The effects of digitalization on seafarers' mental health and digital fatigue are becoming increasingly important in the maritime industry. The aim of this study is to investigate the effects of digital fatigue and mental health on seafarers. Data was collected through a questionnaire survey and analysed using regression analysis and the Delphi method. In the first part, the criteria affecting the level of digital fatigue and mental health of seafarers were identified, considering factors such as sleep patterns, prolonged screen use and working hours. The findings indicate a negative correlation between digital screen usage, digital workload, sleep patterns and social isolation, and mental health status. Prolonged screen use and high digital communication intensity were identified as significant contributors to the mental health challenges faced by seafarers. Furthermore, the study highlights the beneficial impact of stress management techniques and access to psychological support on mental health outcomes. This study aims to provide guidance to authorities and maritime agencies by providing important information to understand the impact of digitalization on seafarers in the maritime sector.

Ozone treatment regulated the anti-exercise fatigue effect of fresh-cut pitaya polyphenol extracts

The anti-exercise fatigue effect of plant polyphenols is closely related to the content, composition, and extractability of phenolic substances. According to our previous findings, ozone treatment significantly affected the biological effects of fresh-cut pitaya polyphenols. Therefore, this study used C57BL/6 J mice to explore the regulatory mechanism of ozone treatment on the anti-exercise fatigue effect of fresh-cut pitaya polyphenol extract. The result showed that fresh-cut pitaya polyphenols treated with ozone (OP) have a better effect. Compared with the untreated group, the exhaustion time of the OP group was 11.86% longer, the total antioxidant capacity was 54.17% higher, the MDA content was 32.8% lower, and the liver glycogen content was 85.71% higher. The OP group also better regulated substrate metabolism, protecting muscle and visceral weight. The results of RT-PCR were consistent with the results of network pharmacology, and the expression of PI3K and AKT was activated, while SRC and STAT3 were down-regulated. Furthermore, pitaya polyphenols have been demonstrated to exert anti-fatigue effects by increasing the diversity of gut microbiota species. In summary, ozone treatment is a feasible way to improve the nutrition of polyphenols.

Neighborhood disadvantage and pain-related experiences in a pain psychology clinic: The mediating roles of pain catastrophizing and pain-related fear

This study investigated the relationship between neighborhood disadvantage, measured by the Area Deprivation Index (ADI), and pain-related variables in a pain psychology clinic. We also examined the sequential mediating roles of pain catastrophizing and pain-related fear on these relationships. Participants (N = 509) completed questionnaires assessing usual pain intensity, fatigue, emotional distress, and interference with daily activities. The mean ADI score was 32.57 (SD = 22.65), with scores ranging from 1 to 100. Linear regression analysis, adjusting for age and gender, revealed that higher ADI (i.e., less advantage) was significantly associated with higher scores on pain-related variables (pain intensity: B = 0.026, p < .001; fatigue: B = 0.018, p < .001; emotional distress: B = 0.020, p < .001; interference with daily activities: B = 0.014, p = .006). Sequential mediation analysis revealed pain catastrophizing and pain-related fear mediated these relationships, with significant indirect effects for fatigue (B = 0.001, 95% CI [0.000, 0.002]) and interference with daily activities (B = 0.001, 95% CI [0.001, 0.003]) — but not pain intensity or emotional distress. Pain catastrophizing alone mediated neighborhood disadvantage-pain relationship for all variables. The results suggest that neighborhood disadvantage is associated with higher scores on pain-related experiences and that consistent with the fear avoidance model, pain catastrophizing and pain-related fear may play a role in these relationships for fatigue and interference with daily activities. These findings underscore that neighborhood disadvantage is associated with worse pain-related experiences and highlight the importance of considering neighborhood factors in chronic pain management. PerspectiveThis study identifies potential pathways linking neighborhood disadvantage to chronic pain variables, highlighting the roles of pain catastrophizing and pain-related fear. The findings underscore the need for a holistic approach to pain management that recognizes both individual cognitive-emotional factors and the broader social context in which pain occurs.

A systematic review and meta-analysis of the impact of muscle fatigue on the biomechanics of joint range of motion (ROM) in badminton

This study aims to evaluate the impact of muscle fatigue on the biomechanics of joint range of motion (ROM) in badminton athletes through a systematic literature review and meta-analysis. Muscle fatigue can affect athletic performance, particularly in dynamic movements such as lunges and smashes. Using the Systematic Literature Review (SLR) method and PRISMA, this study identified and analyzed 9 scientific articles from the Scopus and WoS databases published between 2019 and 2024. Meta-analysis was conducted by calculating the Standardized Mean Difference (SMD) and the 95% confidence interval (95% CI). The results showed that ROM in the hip joint significantly decreased after fatigue, with an SMD of -0.56 (95% CI: -0.76 to -0.36), which increases the risk of adductor and abductor injuries. On the other hand, ankle ROM showed no significant changes between pre-fatigue and post-fatigue conditions (SMD = 0.06, 95% CI: -0.13 to 0.25). For the knee joint, significant heterogeneity was found among studies with an I² value of 52% and an overall SMD of -0.01 (95% CI: -0.28 to 0.26), indicating that the effect of fatigue on knee ROM was inconsistent. This study concludes that muscle fatigue plays a crucial role in biomechanical changes that may increase the risk of injury in badminton athletes. Coaches are advised to implement interventions such as dynamic stretching and foam rolling to reduce muscle stiffness and maintain optimal ROM during matches. This study provides a critical scientific basis for developing evidence-based injury prevention programs.

Lack of fusion-induced cracking effect on tensile and fatigue behaviours of laser powder-bed fusion-processed Ti-6Al-4V implant

In the laser powder-bed fusion (L-PBF) of Ti-6Al-4 V (Ti64) alloy, cracking defects often caused by lack-of-fusion (LoF) defects cannot be avoided. These defects strongly impact the structural stability of Ti64 implants. In this work, the influence of LoF defects on the tensile and fatigue behaviours of Ti64 implants at different energy densities is evaluated. Three primary approaches were used to characterise the LoF defects in the 10 mm gauge volume of near-net-shaped produced hourglass samples: Image-J software, scanning electron microscopy (SEM), and X-ray computed tomography (µ-CT). A low-cycle fatigue (LCF) test at a stress ratio of −1 and an extensive fractography study of the fractured Ti64 samples were used to investigate the LoF porosity-induced cracking and fatigue effect. The tensile properties of Ti64 samples processed by the L-PBF are generally more affected by microstructural changes resulting from variations in energy density than by LoF defects. A fine microstructure enhances tensile strength, while a coarser microstructure favours ductility. This is evident in samples LPBF-AD and LPBF-BD1, which demonstrate finer and coarser microstructures but show the lowest (8.31 %) and highest ductility (17.58 %), respectively. The best and worst fatigue performance samples were LPBF-AD (600 MPa) and LPBF-BD2 (200 MPa), respectively, and LoF defects significantly impactedthis finding. Moreover, it has been demonstrated that cracks originate and propagate faster from the surfacethan the internal sites. As a result, the former demonstratesa negative effect on the fatigue life of L-PBF-processed Ti64 samples under cyclic loading. The sub-surface morphologies and pore formation with different energy densities are rationalised by high-fidelity thermal-fluid dynamics simulations.

Design and validation of an electroencephalogram‐supported approach to tracking real‐time cognitive load variations for adaptive video‐based learning

Cognitive load is a critical internal state associated with learners' learning process and significantly influences learning outcomes. With the worldwide popularity of video‐based learning (VBL), tracking real‐time cognitive load variations becomes more and more important for the timely provision of adaptive learning support during the learning process. This study proposed and validated an electroencephalogram (EEG)‐supported approach to tracking real‐time cognitive load variations during continuous VBL. We recruited 108 healthy adult participants to watch a specially designed video lecture with a sequence of interconnected slides of equal length. EEG signals were continuously recorded throughout the session. The video lecture was designed with varying levels of content difficulty (ie, rated from 1 to 5) across slides and was narrated at three different speeds (ie, slow, normal and fast) to induce cognitive load variations. For each slide, the cognitive load was quantified using both subjective ratings (ie, self‐reported difficulty) and an EEG‐derived measure (ie, alpha power). Through linear mixed model analysis, we demonstrated the feasibility of using alpha power to track real‐time cognitive load variations during the continuous VBL process after controlling the effect of mental fatigue. This study provides a foundation for developing learning enhancement technologies that enable the timely provision of adaptive learning support in VBL. Practitioner notesWhat is already known about this topic Video‐based learning has become a prevailing learning method for the current generation. Tracking the internal learning state of learners is essential for the timely provision of adaptive learning support during the video‐based learning process. Cognitive load is a critical aspect of internal learning state. While EEG has been proven to be valuable in assessing average cognitive load of a task, few studies have investigated the feasibility of utilizing EEG to track real‐time cognitive load variations in a task. What this paper adds An EEG‐supported approach was proposed to track real‐time cognitive load variations in video‐based learning. A high consistency was found between subjective ratings and EEG‐derived measure of cognitive load. The presence of mental fatigue exerted a significant impact on EEG‐derived measure of cognitive load. Implications for practice and/or policy Generative AI can be leveraged to facilitate mass production of lectures required in the approach. Real‐time tracking of cognitive load variations in video‐based learning enables the timely provision of adaptive learning supports. Additional research is warranted to mitigate the effect of mental fatigue on real‐time tracking of cognitive load variations.

Ninja turtles: an experimental evaluation of potential anthropogenic barriers to movement for a freshwater turtle

AbstractAnthropogenic landscape change due to urbanization, agriculture, and resource extraction results in barriers within the landscape. Artificial structures such as roads, fences, levees, and dams limit the movement of some species and further fragment residual habitat. In this study, we investigated the ability of Eastern long‐necked turtles (Chelodina longicollis) to cross various terrestrial obstacles commonly encountered throughout their habitat. We tested two types of fences (chicken wire and hinged joint exclusion fencing) commonly used in agricultural systems and three sizes of rocks (gravel, cobbles, and boulders) often used for road construction, erosion control, and waterway stabilization. We examined the success rates of turtles in crossing obstacles, the effect of fatigue on crossing attempts, and the impact of individual boldness on movement behaviour. Turtles had high success rates in crossing gravel (85.4%), cobbles (86%), boulders (73.3%) and hinged joint exclusion fencing (94.7%). Turtles did not successfully cross chicken wire fencing (0%) despite 276 attempts. A significant fatigue effect occurred throughout the experiment, with turtles making an average of 3.94 (±1.42 SE) fewer attempts at the end of the experiment (day 18) than on day 1. Bolder turtles were faster at crossing obstacles, but boldness had no influence on obstacle‐crossing success. Our results highlight the need for thoughtful selection of waterway, wetland, and riparian bordering infrastructure and the fatiguing impact of constant exposure to anthropogenic barriers for wildlife.

Cognitive Fatigue, Humor, and Physical Activity: A Field Experiment Testing Whether Humorous Messages Promote Walking in Cognitively Fatigued Individuals

ABSTRACT Despite the success of humorous messages in various health interventions, its role in promoting physical activity (PA) remains understudied. This study addresses this gap by investigating the effectiveness of humorous messages in a 2-week smartphone-based intervention aimed at promoting walking behavior, particularly amongst cognitively fatigued individuals. Female participants (n = 57; M age = 32.00; SD = 4.385) received humorous, nonhumorous, or a mix of both messages (in the form of memes) via a study-specific application, with cognitive fatigue measured daily. Panel linear regression models revealed a significant positive interaction between cognitive fatigue and message type. Our results suggest that the resilience of humorous messages to cognitive fatigue and their potential as motivational tools position them as a more robust choice for promoting PA. Importantly, when cognitively fatigued individuals received humorous messages, their walking behaviors showed no significant change, in contrast to the detrimental impact of nonhumorous messages on exercise. Recognizing the differential effects of cognitive fatigue on message effectiveness and considering the potential of humorous messages as motivational tools offers a valuable perspective for tailoring interventions to individual states.

Concussion leads to opposing sensorimotor effects of habituation deficit and fatigue in zebrafish larvae.

Concussion, or mild traumatic brain injury, is caused by sudden mechanical forces impacting the brain either directly or through inertial loading. This can lead to physical, behavioural and cognitive impairments. Despite concussion being a significant health issue, our understanding of the relationship between initial impact force and the subsequent neurological consequences is not well understood. Previously, we established a model of concussion in zebrafish larvae. Here, we further investigate concussions of varying severities in zebrafish larvae using linear deceleration. Using an acoustic assay to monitor the larval sensorimotor behaviour, we found that different parameters of the resulting escape behaviour are modulated by the impact force of the preceding concussive insult. To investigate the relative contributions of habituation performance and fatigue on the escape response behaviour, we constructed a neurocomputational model. Our findings suggest that a concussive impact initially affects habituation performance at first and, as the impact force increases, fatigue is induced. Fatigue then alters the escape response behaviour in an opposing manner.

Acute Effect of Oral N-Acetylcysteine Supplementation on Fatigue Effect and Isometric Force Production in Physically Active People

The main objective of this study was to assess the ergogenic effect of N-acetylcysteine (NAC) on myotendinous isometric force production in physically active people after being subjected to a fatigue protocol. Twenty-three physically active people were randomly divided into the following two groups: NAC (n = 12; age = 26.8 ± 4.5 years, height = 173.1 ± 7.2 cm, and weight = 75.5 ± 7.5 kg), who received 2400 mg oral NAC, and control (n = 11; age = 23.4 ± 5.8 years, height = 175.9 ± 4.5 cm, and weight = 72.3 ± 9.9 kg), who received a placebo, for eight days. The isometric force production was assessed pre- and post-NAC supplementation during a maximal voluntary contraction test (MVC) and also during a fatigue protocol composed of seven sets of ten maximal isometric contraction repetitions of 5 s, with 5 s of rest between repetitions and 20 s between sets. No differences were observed between the groups in the force production values at any moment, and no side effects were found after NAC supplementation. After supplementation, a significant decrease in force was observed in both groups, but this significant loss of force started one set later in the NAC group compared to the control group (4th set vs. 5th set), which could be an ergogenic effect of the treatment. Therefore, oral daily supplementation with 2400 mg of NAC for eight days, could delay the decrease in force production during an isometric exercise protocol and without adverse side effects.

Circadian Rhythm and Physical Fatigue Separately Influence Cognitive and Physical Performance in Amateur Athletes.

Circadian rhythm (CR) influences various physiological functions, including physical and cognitive performance, which fluctuate throughout the day. The present study aimed to investigate the combined and separate effects of CR and physical fatigue on cognitive and physical performance. A sample of 18 amateur athletes was subjected to a series of tests at three different times of the day: morning, afternoon, and evening. Fatigue was induced following an isokinetic concentric exercise combined with a 20 min treadmill run, followed by assessments of selected physical and cognitive tasks. A repeated measure ANOVA did not reveal an interaction between CR and fatigue in cognitive performance (p > 0.05). However, a significant main effect of fatigue was observed in visual reaction time (VisRT) across all three timepoints. Moreover, peak torque (PT) and the peak torque fatigue index (PTFI) showed significant differences between the three times of the day, peaking in the evening. Although we found no interaction between CR and the physical fatigue state on selected cognitive parameters at the three times of the day, a separate effect of fatigue on cognitive performance was identified. Additionally, physical parameters exhibited peak values occurring in the evening hours. Future research should further explore underlying mechanisms that potentially influence cognitive performance at different times of the day.

Subjective and objective effects of anxiety and fatigue on social function in patients with enterostomy and their family caregivers.

Many patients with enterostomy and their family caregivers experience severe anxiety and fatigue, which affects their participation in normal social activities and family life, resulting in impaired social function. The purpose of this study was to understand the status of social function of patients with enterostomy and their family caregivers;at the same time to analyze the subjective and objective effects of anxiety and fatigue on their social functions. The self-made general information questionnaire, WHO Social Disability rating Scale, Miao Yu's Multidimensional Fatigue Scale-20 and Zung et al. 's Self-rating Anxiety Scale were used to investigate the general situation, social function, fatigue and anxiety of enterostomy patients and their family caregivers who came to the hospital for treatment from March 28, 2023 to November 30, 2023. SPSS27.0 was used to complete the statistical analysis of the data, and AMOS26.0 was used to establish the structural equation model to complete the subject and object effect analysis. A total of 260 pairs of enterostomy patients and their family caregivers were included in this study. The social function scores of enterostomy patients and their family caregivers were (8.80±3.44) and (6.44±3.60). The anxiety scores were (37.81±7.60) and (34.73±7.50). The fatigue scores were (63.35±12.80) and (51.21±12.38).The results of the subject-object effect analysis reported the subject effect: the anxiety of patients with enterostomy had a significant positive impact on the degree of social dysfunction (β = 0.154, P = 0.015); The fatigue of patients with enterostomy had a significant positive effect on the degree of social dysfunction (β = 0.132, P = 0.034). The anxiety of family caregivers had a significant positive effect on the degree of social dysfunction (β = 0.161, P = 0.023). The fatigue of family caregivers had a significant positive effect on the degree of social dysfunction (β = 0.201, P = 0.005). In terms of object effects: only the fatigue of family caregivers had a significant positive impact on the degree of social dysfunction of enterostomy patients (β = 0.224, P < 0.001), and other ways had no object effects. Patients with enterostomy and their family caregivers have serious social function defects. Clinical medical staff should take care of them as a whole in order to better return to family and society after surgery.

The Influence of Emotional Intelligence on Psychiatric Nurses' Care Behavior, and the Chain Mediating Role of Compassion Fatigue and Perception of Management.

To investigate psychiatric nurses' emotional intelligence and its effect on care behavior, while also examining the mediating effect of compassion fatigue and perception of management. This cross-sectional study was conducted in several specialized psychiatric hospitals with 360 psychiatric nurses. Self-report surveys were administered, which included the Caring Factor Survey-Caring of Manager, Caring Behaviors Inventory, Compassion Fatigue Short Scale, and Wong Law Emotional Intelligence Scale. Data were analyzed using descriptive, correlation, and path analyses. Mean score for care behavior was 4.78 (SD = 0.83), which was at a moderate level. Compassion fatigue exhibited negative correlations with other variables. Results of mediation effect analysis showed that emotional intelligence directly predicted care behavior (p < 0.001). Emotional intelligence also indirectly affected care behavior through the mediating roles of perception of management and compassion fatigue, and affected care behavior through the chain mediation effect of perception of management and compassion fatigue. Nurse managers should pay attention to the influence of emotional intelligence on care behavior and improve care behavior by strengthening leadership and alleviating compassion fatigue. [Journal of Psychiatric Nursing and Mental Health Services, xx(xx), xx-xx.].

Viable strategies for enhancing performance in ball sports by mitigating mental fatigue: A systematic review.

Ball sports demand precise control of body and ball while executing tactics and team coordination, which leads to cognitive depletion and mental fatigue. The detrimental effects of mental fatigue on physical, technical, cognitive, and tactical performance in ball sports are evident, highlighting the need for effective management of mental fatigue as a crucial component of modern sports science. This review aims to systematically study and integrate existing experiments on mental fatigue recovery interventions to identify viable strategies for mitigating its impacts. Following PRISMA guidelines, electronic databases including Web of Science, PubMed, SPORTDiscus, and Scopus were used for literature screening. Studies that induced mental fatigue followed by interventions aimed at mental fatigue recovery were included in this review, resulting in 6 articles primarily focused on basketball, soccer, and golf. Short-term interventions such as music listening, mindfulness training, self-talk, and natural visual stimuli have been shown as effective strategies to alleviate mental fatigue and enhance technical and cognitive performance in ball sports. However, their practical application in real-game environments requires further research and validation. Additionally, future research should explore defensive skills and tactical performance as viable directions for study.

Creep-thermal fatigue behavior of thin-walled structures with holes and a creep-thermal fatigue-oxidation phase field model

An experiment was conducted to evaluate the creep-thermal fatigue (CTF) behavior of thin-walled structures with holes. To achieve this, a high-temperature hold phase was added in the testing. The crack propagation of CTF is driven by the combined effects of creep, thermal fatigue, and oxidation. Therefore, a creep-thermal fatigue-oxidation phase field model was developed to simulate CTF behavior. The model accounts for the interaction between creep damage and fatigue damage, as well as the oxidation effect. A creep degradation function was formulated based on classical damage theory, and two creep damage models were compared. Two physically meaningful strategies were proposed to describe oxidation-induced fatigue damage. Finally, the applicability of model to creep-fatigue was validated.

The Effects of Cold Exposure, Hypoxia, and Fatigue on Pistol Marksmanship and Target Engagement Decision Making in Trained Marksmen.

Segovia, M, Salmon, OF, Ugale, C, and Smith, CM. The effects of cold exposure, hypoxia, and fatigue on pistol marksmanship and target engagement decision making in trained marksmen. J Strength Cond Res 38(11): e686-e694, 2024-This study aimed to examine the effects of cold exposure, hypoxia, and fatigue on pistol marksmanship and target engagement in trained marksmen. Twelve healthy subjects (mean ± SD age: 28.8 ± 4.0 years) performed 3 testing visits under normal/normoxic [Norm 21 ] (24° C; 21% FiO 2 ), cold/normoxic [Cold 21 ] (10° C; 21% FiO 2 ), and cold/hypoxic [Cold 14 ] (10° C; FiO 2 : 14.3) conditions. Pistol marksmanship and target engagement were assessed through draw time (DT) and shoot-no-shoot (SNS) courses of fire. The 2 protocols were performed before (T preF ) and immediately after (T postF ) a sandbag deadlift fatiguing protocol. Significance was set at p < 0.05. Significant condition × time interactions ( p = 0.01-0.03) were found for accuracy SNS (SNS acc ), misses SNS (SNS miss ), and total shots SNS (SNS tot ). Follow-up analyses indicated that SNS acc increased by 14.3% ( p = 0.03), SNS miss decreased by 34.7% ( p = 0.02), and SNS tot decreased by 10.6% ( p = 0.04) from T preF to T postF during the Cold 21 condition alone. No significance was found for these in the Norm 21 ( p = 0.08-0.22) or Cold 14 ( p = 0.18-0.47) conditions. Total time (SNS T ) to completion of the SNS ( p = 0.09) and DT ( p = 0.14) showed no significance across time or condition. Significant difference across time for Cold 14 ( p = 0.03-0.02) for reaction time was found. Exercise likely resulted in increased thermogenesis that improved tactically relevant motor skills including SNS acc , decreased SNS miss , and SNS tot in Cold 21 , but not Cold 14 . The additive effect of hypoxia coupled with exercise in the Cold 14 condition did not improve tactical performance, suggesting multi-stressor environments result in competing physiological responses. Tactical strength and conditioning specialists as well as operators should aim to improve thermoregulation during Cold 21 conditions, with exercise as a possible intervention.

Kinetic analysis of change of direction simulating a defensive action in soccer players with and without acute fatigue

The objective of this study is to analyse the kinetic effects of acute fatigue during a 45° change of direction executed with the non-dominant limb, emulating a typical defensive action during pressing in soccer. Seventeen male professional soccer players (age: 21.7 ± 5.4 years) performed a 45° change of direction before and after a fatigue protocol. Participants were instructed to execute an approach run as quickly as possible, to change direction with their non-dominant foot on a force platform, and then continue running with the aim of stopping against an opponent. Times, forces, impulses, and force rates for different subphases during support were compared. Speeds remained consistent across pre-fatigue (4.53 ± 0.55 m s-1) and post-fatigue (4.58 ± 0.70 m s-1) trials. The results indicated a decrease in braking time (p = 0.01), impulse associated with the braking phase (p < 0.01), and impulse during body weight lifting (p = 0.01) under acute fatigue conditions. These changes suggest that, under acute fatigue, soccer players may not decelerate sufficiently in the initial direction of the run and may raise their body less in the first step after the change of direction. Maximum force values and force rates did not show significant changes; however, they were sufficiently high to suggest a potential injury risk in both conditions.