Fatigue Index Research Articles

A two-scale approach for assessing the role of defects in fatigue crack nucleation in metallic structures

Metal structures often exhibit macroscopic defects from which cracks can nucleate during cyclic loading. The current work presents a two-scale approach to enable the prediction of crack nucleation from such defects by taking into account local microstructure features. The geometrical description of the defect and associated non-homogeneous strain fields are modeled using a macroscale model which employs a continuum elastoplastic material model for cyclic deformation. The cyclic deformation of the microstructure near the defect is modeled using a mesoscale model which employs a crystal plasticity material model and uses multiple realizations to address the statistical microstructure variability. The boundary conditions of the mesoscale model are extracted from the macroscale model. By simulating the deformation of the microstructure using the strain fields near the defect and by introducing a fatigue indicator parameter for crack nucleation, along with the weakest-link based upscaling methodology, the developed approach enables the prediction of the distribution of crack nucleation life. The approach is used for analyzing different defects for crack nucleation by considering local grain orientations. The predictions are shown to not only capture phenomena such as scatter, size effects, etc. qualitatively, but also agree with a classical engineering approach and experimentally reported data sets quantitatively.

Analysis of rolling contact and tooth root bending fatigue in a new high-strength steel: Experiments and micromechanical modelling

To find materials that meet the future requirements of increasing load density in wind turbine gear structures, the commonly used reference material, 18CrNiMo7-6, and another high-strength steel were analysed. Their fatigue properties were studied through rolling contact fatigue (RCF) and gear tooth root bending fatigue (TRBF) tests. The reference steel exhibited better fatigue performance under RCF conditions compared to the new steel; however, it was outperformed by the new steel under TRBF conditions. This study aims to understand gear contact fatigue at the microscopic level, moving beyond the macroscopic focus that dominates current research literature. To establish the causal link between the varied fatigue performance observed in these materials, we proposed a multiscale modelling workflow based on crystal plasticity. This crystal plasticity framework is combined with the fatigue indicator parameter (FIP) to explore the fatigue resistance of materials subjected to RCF and TRBF conditions. Emphasis has been placed on the role of retained austenite (RA) in fatigue performance. Utilizing representative elementary volumes (REVs) generated based on statistically representative crystallographic features and measured size distribution of RA, we examined the effects of various RA levels on fatigue resistance. Our findings reveals that the fatigue damage accumulation is significantly influenced by the level of RA. Different fatigue damage accumulation behaviours were observed under RCF and TRBF conditions. These insights offer new perspectives on RA’s role in fatigue resistance and highlight its complex influence under varied loading conditions.

Determination of walking energy expenditure as an indicator of walking fatigue

Determination of walking energy expenditure as an indicator of walking fatigue

A non-antibiotic erythromycin derivative improves muscle endurance by regulating endogenous anti-fatigue protein orosomucoid in mice.

At present, there are no official approved drugs for improving muscle endurance. Our previous research found acute phase protein orosomucoid (ORM) is an endogenous anti-fatigue protein, and macrolides antibiotics erythromycin can elevate ORM level to increase muscle bioenergetics and endurance parameters. Here, we further designed, synthesized and screened a new erythromycin derivative named HMS-01, which lost its antibacterial activity in vitro and in vivo. Data showed that HMS-01 could time- and dose-dependently prolong mice forced-swimming time and running time, and improve fatigue index in isolated soleus muscle. Moreover, HMS-01 treatment could increase the glycogen content, mitochondria number and function in liver and skeletal muscle, as well as ORM level in these tissues and sera. In Orm-deficient mice, the anti-fatigue and glycogen-elevation activity of HMS-01 disappeared. Therefore, HMS-01 might act as a promising small molecule drug targeting ORM to enhance muscle endurance.

Acute ingestion of acetaminophen improves cognitive and repeated high intensity short-term maximal performance in well-trained female athletes: a randomized placebo-controlled trial

This study examined the effect of acute acetaminophen (ACTP) ingestion on physical performance during the 5 m shuttle run test (5mSRT), attention, mood states, and the perception of perceived exertion (RPE), pain (PP), recovery (PRS), and delayed onset of muscle soreness (DOMS) in well-trained female athletes. In a randomized, placebo-controlled, double-blind, crossover trial, fifteen well-trained female athletes (age 21 ± 2 years, height 165 ± 6 cm, body mass 62 ± 5 kg) swallowed either 1.5 g of ACTP or 1.5 g of placebo. The profile of mood states (POMS) and digit cancellation (DCT) were assessed 45 min postingestion, and 5mSRT was performed 60 min postingestion. The RPE and PP were determined immediately after each 30-s repetition of the 5mSRT, and the PRS and DOMS were recorded at 5 min and 24 h post-5mSRT. For the 5mSRT, ACTP ingestion improved the greatest distance (+ 10.88%, p < 0.001), total distance (+ 11.33%, p = 0.0007) and fatigue index (+ 21.43%, p = 0.0003) compared to PLA. Likewise, the DCT score was better on the ACTP (p = 0.0007) than on the PLA. RPE, PP, PRS, and DOMS scores were improved after ACTP ingestion (p < 0.01 for all comparisons) compared to PLA. POMS scores were enhanced with ACTP ingestion compared to PLA (p < 0.01). In conclusion, this study indicates that acute acetaminophen ingestion can improve repeated high intensity short-term maximal performance, attention, mood states, and perceptions of exertion, pain, recovery, and muscle soreness in well-trained female athletes, suggesting potential benefits for their overall athletic performance and mood state.

Framework and Function of Integrated Water Resources Management in Support of Sustainable Development

Sustainable Development Goal 6 addresses water issues, and Target 6.5.1 sets a goal to implement integrated water resources management (IWRM) at all levels. The reporting system shows slow progress, which indicates that changes are needed. The assessments focus mainly on the function of IWRM as a framework of institutional arrangements and less on its function as a process for water resources management, with emphasis on practices like multi-objective planning and stakeholder participation. While IWRM has a rich body of knowledge and wide recognition among water management communities, it is still misunderstood and criticized by some stakeholders, even after 25 years of explanations. While its support base appears stable, indications of fatigue and waning interest in IWRM point to the need for fresh explanations and demonstrations. These can be facilitated by distinguishing the functionalities of IWRM as a framework and a process. SDG data focuses on its framework function, which generally tracks the status of environmental governance in countries. Case studies provide better indicators of its use as a process, but their narratives may not be persuasive. If educators adopt the framework and function model of IWRM advocated in the paper, the narratives can improve and facilitate greater acceptance. Advancement of IWRM implementation to support the Sustainable Development Goals requires continued support by the Global Water Partnership, which might be bolstered by cooperation with international water associations for standardization, accreditation, and credentialing. IWRM’s future implementation will also depend on its adoption among educators and on interdisciplinary approaches.

Preventive effect of one-session brief focused attention meditation on state fatigue: Resting state functional magnetic resonance imaging study

IntroductionThe extended practice of meditation may reduce the influence of state fatigue by changing neurocognitive processing. However, little is known about the preventive effects of one-session brief focused attention meditation (FAM) on state fatigue in healthy participants or its potential neural mechanisms. This study examined the preventive effects of one-session brief FAM on state fatigue and its neural correlates using resting-state functional MRI (rsfMRI) measurements. MethodsWe randomly divided 56 meditation-naïve participants into FAM and control groups. After the first rsfMRI scan, each group performed a 10-minute each condition while wearing a functional near-infrared spectroscopy (fNIRS) device for assessing brain activity. Subsequently, following a second rsfMRI scan, the participants completed a fatigue-inducing task (a Go/NoGo task) for 60 min. We evaluated the temporal changes in the Go/NoGo task performance of participants as an indicator of state fatigue. We then calculated changes in the resting-state functional connectivity (rsFC) of the rsfMRI from before to after each condition and compared them between groups. We also evaluated neural correlates between the changes in rsFC and state fatigue. Results and discussionThe fNIRS measurements indicated differences in brain activity during each condition between the FAM and control groups, showing decreased medial prefrontal cortex activity and decreased functional connectivity between the medial prefrontal cortex and middle frontal gyrus. The control group exhibited a decrement in Go/NoGo task performance over time, whereas the FAM group did not. These results, thus, suggested that FAM could prevent state fatigue. Compared with the control group, the rsFC analysis revealed a significant increase in the connectivity between the left dorsomedial prefrontal cortex and right superior parietal lobule in the FAM group, suggesting a modification of attention regulation by cognitive effort. In the control group, increased connectivity was observed between the bilateral posterior cingulate cortex and left inferior occipital gyrus, which might be associated with poor attention regulation and reduced higher-order cognitive function. Additionally, the change in the rsFC of the control group was related to state fatigue. ConclusionOur findings suggested that one session of 10-minute FAM could prevent behavioral state fatigue by employing cognitive effort to modify attention regulation as well as suppressing poor attention regulation and reduced higher-order cognitive function.

The effects of aerobic gymnastics training on performance-related variables in an elite athlete: a 2-year follow-up study.

This study investigates individual performance adaptations on 2years of training between European Aerobics Championships. An elite, 22-year-old aerobic gymnast performed postural coordination test, Y-Balance test, squat and countermovement jumps, 60s test of repeated jumps, an isokinetic leg muscle strength test, and the Wingate test. Postural stability and flexibility improved in terms of increased distance achieved in the Y-Balance test in the anterior (by 6.3%), posteromedial (by 2%), and posterolateral (by 4.8%) directions. Lower limb muscular endurance also increased, which can be corroborated by a reduced fatigue index in the 60s test of repeated jumps (from 42% to 27% after the 1st and to 22% after the 2nd year of training). In addition, mean power increased during dominant (by 23.2% at 60°/s and by 18.5% at 180°/s) and non-dominant leg extension (by 4.9% at 180°/s and by 15.5% at 300°/s), plus dominant leg flexion (by 2.0% at 60°/s and by 6.9% at 300°/s). Similarly, peak torque/body weight ratio increased during dominant (by 24.9% at 60°/s, by 11.5% at 180°/s, and by 2.1% at 300°/s) and non-dominant leg extension (by 0.5% at 60°/s and by 6.4% at 300°/s), plus dominant leg flexion (by 1.7% at 60°/s and by 5.4% at 300°/s). However, 2years of training failed to show any significant improvements in the explosive power of lower limbs and anaerobic performance. These findings indicate that general aerobic gymnastics training without any specific inputs leads to performance adaptation, namely, in abilities closely related to competition routine (dynamic balance and strength endurance of lower limbs).

Stored energy density solution for TSV-Cu structure deformation under thermal cyclic loading based on PINN

TSV-Cu is widely used for chip interconnects, where high testing costs and complex crystal plasticity finite element (CPFE) limit the research of its deep microplastic evolution process. Considering the stored energy density (SED) based on dislocation density and plastic work as a fatigue indicator factor (FIP), this paper proposes for the first time a physics-informed neural network (PINN) framework based on SED, which aims to achieve the solution of SED distributions quickly and efficiently to save computational time and cost. The grain orientation, geometrical compatibility factor, back stress, and effective plastic strain are taken into account as inputs to the PINN model. The total dislocation density is used as an indirect solution variable to construct the associated loss boundary terms, which results in the solution of the SED. The results of the two real EBSD tests show that the PINN model is able to accurately and sensitively predict the SED concentration distribution for different thermal cycle loadings, and maintains a high degree of agreement with the CPFE calculation results. Moreover, The superiority of PINN over other machine learning algorithms in terms of physical model interpretation and prediction accuracy is verified. These make it a reality for PINN to solve for the FIP distribution for the first time, and to accurately and quickly predict the location of crack initiation.

Effect of grain orientation distribution on the mechanical properties of Al-7.02Mg-1.78Zn alloys

PurposeDuring the forming process, aluminum alloy sheets develop various types of textures and are subjected to cyclic loading as structural components, resulting in fatigue damage. This study aims to develop polycrystalline models with different orientation distributions and incorporate suitable fatigue indicator parameters to investigate the effect of orientation distribution on the mechanical properties of Al-7.02Mg-1.78Zn alloys under cyclic loading.Design/methodology/approachIn this study, a two-dimensional polycrystalline model with 150 equiaxed grains was constructed based on optical microscope images. Subsequently, six different orientation distributions were assigned to this model. The fatigue indicator parameter of strain energy dissipation is utilized to analyze the stress response and fatigue crack driving force in polycrystalline models with different orientation distributions subjected to cyclic loading.FindingsThe study found that orientation distribution significantly influences fatigue crack initiation. Orientation distributions with a larger average Schmid factor exhibit reduced stress response and lower fatigue indicator parameters. Locations with a larger average Schmid factor experience greater plastic deformation and present a higher risk for fatigue crack initiation. RVE with a single orientation undergoes more rotation to reach cyclic steady state under cyclic loading due to the ease of deformation transfer.Originality/valueCurrently, there are no reports in the literature on the calculation of fatigue crack initiation for Al-Mg-Zn alloys using the crystal plasticity finite element method. This study presents a novel strategy for simulating the response of Al-7.02Mg-1.78Zn materials with different orientation distributions under symmetric strain cyclic loading, providing valuable references for future research.

A physics‐informed neural network framework based on fatigue indicator parameters for very high cycle fatigue life prediction of an additively manufactured titanium alloy

AbstractThe exploitation of fatigue life prediction methods based on fatigue indicator parameters revealed the influence of the defect size, position, and morphology on the fatigue life and fatigue behavior of additively manufactured metals. Meanwhile, Data‐driven life prediction methods are time‐efficient but inexplainable. Current machine learning‐based fatigue life prediction methods call for not only the accuracy but also the interpretability and stability of prediction results. Thus, the fusion of physical methods and machine learning methods has been a prevailing research topic in fatigue life prediction. In this study, a novel physics‐informed neural network framework is proposed by integrating a fatigue indicator parameter based on defects into the physical constraints term of a loss function. This method outperforms conventional machine learning methods in high‐cycle and very high‐cycle regimes, exhibiting superior prediction performance and generalization ability. Furthermore, the prediction results can be explained from a physical standpoint, correlating with the applicability range of the introduced physical equation describing defect positions.

Analisis Hubungan Antara Mood Atlet Dengan Tingkat Keberhasilan Snatch Pada Atlet Angkat Besi PABSI JATIM Surabaya

Mood or mood is an important part of a person's psychological well-being. Several studies show that physical exercise can positively influence mood. One of the factors that influences an athlete's mental and emotional readiness is mood. Mood Profile for Weightlifting athletes is an important factor that needs to be analyzed. This research aimed to determine the relationship between athletes' moods and the success rate of snatches in weightlifting athletes at PABSI Jatim Surabaya before PORPROV 2025. This qualitative research used mixed methods. Mixed methods is a research approach that combines or associates qualitative and quantitative forms. A research method that uses qualitative data and is described descriptively. The Total Sample Method is a sampling method with the number of samples equal to the population. The sample was taken using total sampling because the population was less than 100 and the entire population was used as the research sample (Masturoh &amp; Anggita, 2018). The sample that can be used is the population sample taken from Provincial Weightlifting athletes (aged 13 - 23 years) totaling 8 people and is only limited so that they can be used as one training group by filling in a mood profile questionnaire and recording the snatch technique. Of the 8 respondents who took the snatch test, all appeared confident. However, when holding and doing the snatch, there is a feeling of doubt and anxiety about whether or not you can accept the weight of the snatch if it is already above. However, after doing the snatch test, he also felt happy by releasing endorphins in his body. The results of the before and after research show that the "Medium" category with the highest percentage is the anger indicator (AMR) of 71.43% and 42.86%, and the confused mood indicator (SSB) of 53.57% and 71%. Indicators with moderate percentages include full energy indicators (PNT) of 85.71% and 75%, self-assessment (PDR) of 80.36% and 80%, and depression (DPS) of 44.64% and 63%. The percentage of fatigue indicators (KLH) was 53.57% and 42.85% and tension indicators (KTG) were 57.14% and 50%. The conclusion of the research on the analysis of the relationship between athlete's mood and the success rate of snatches in weightlifting athletes at PABSI East Java, Surabaya is in the "Medium" condition. Negative mood conditions in the "Medium" category such as fatigue, anger, tension, confusion, and depression indicate that athletes are not feeling stressed mentally and physically. Meanwhile, positive mood conditions in the "Medium" category make athletes have a good mood, such as being full of energy and self-confidence. This is possible because the training portion is good and the conditions leading to PORPROV 2025 are still quite long. So there are still many athletes who experience good mood conditions so the presence of this athlete's mood also supports the athlete's successful performance both during training and during competitions.

Effects of Short-Rest Interval Time on Resisted Sprint Performance and Sprint Mechanical Variables in Elite Youth Soccer Players

This study explored the impact of short rest intervals on resisted sprint training in elite youth soccer players, specifically targeting enhanced initial-phase explosive acceleration without altering sprint mechanics. Fifteen U19 soccer players participated in a randomized crossover design trial, executing two sprint conditions: RST2M (6 sprints of 20 m resisted sprints with 2 min rest intervals) and RST40S (6 sprints of 20 m resisted sprints with 40 s rest intervals), both under a load equivalent to 30% of sprint velocity decrement using a resistance device. To gauge neuromuscular fatigue, countermovement jumps were performed before and after each session, and the fatigue index along with sprint decrement percentage were calculated. Interestingly, the results indicated no significant differences in sprint performance or mechanical variables between RST2M and RST40S, suggesting that the duration of rest intervals did not affect the outcomes. Horizontal resistance appeared to mitigate compensatory patterns typically induced by fatigue in short rest periods, maintaining effective joint movement and hip extensor recruitment necessary for producing horizontal ground forces. These findings propose a novel training strategy that could simultaneously enhance sprint mechanics during initial accelerations and repeated sprint abilities for elite youth soccer players—a methodology not previously employed

Immediate but not prolonged effects of submaximal eccentric vs concentric fatiguing protocols on the etiology of hamstrings' motor performance fatigue.

Our study aimed to compare the immediate and prolonged effects of submaximal eccentric (ECC) and concentric (CON) fatiguing protocols on the etiology of hamstrings' motor performance fatigue. On separate days, 16 males performed sets of 5 unilateral ECC or CON hamstrings' contractions at 80% of their 1 Repetition Maximum (1RM) until a 20% decrement in maximal voluntary isometric contraction (MVC) torque was reached. Electrical stimulations were delivered during and after MVCs at several time points: before, throughout, immediately after (POST) and 24h (POST 24) after the exercise. Potentiated twitch torques (T100 and T10, respectively) were recorded in response to high and low frequency paired electrical stimulations, and hamstrings' voluntary activation (VA) level was determined using the interpolated twitch technique. For statistical analysis, all indices of hamstrings' motor performance fatigue were expressed as a percentage of their respective baseline value. At POST, T100 (ECC: -13.3%; CON: -9.7%; p < 0.001), T10 (ECC: -5.1%; CON: -11.8%; p < 0.05) and hamstrings' VAlevel (ECC: -3.0%; CON: -2.4%; p < 0.001) were significantly reduced from baseline, without statistical differences between fatigue conditions. At POST24, all indices of hamstrings' motor performance fatigue returned to their baseline values. These results suggest that the contribution of muscular and neural mechanisms in hamstrings' motor performance fatigue may not depend on contraction type. This may have implications for practitioners, as ECC and CON strengthening could be similarly effective to improve hamstrings' fatigue resistance.

The effects of sodium bicarbonate ingestion and sports performance in female athletes during different phases of the menstrual cycle

Sodium Bicarbonate (SB) is recognised as an effective ergogenic aid for enhancing high-intensity exercise capacity and performance. However, the lack of consistency in scientific research findings involving female participants and SB, attributed to the variations in hormonal profiles during the menstrual cycle (MC), has led to a disproportionate focus on studies exclusively conducted in a male population. Purpose: The purpose of the present study is to assess the effects of SB ingestion and sports performance in female athletes during different phases of the MC. There is currently no evidence showing whether different phases of the MC would enhance exercise performance following SB ingestion. Given this gap in the literature, it yet remains unclear that if different hormonal fluctuations throughout the MC affected absorption, nutrient capacity, or exercise performance, the stimulating effect of buffering agents could be further enhanced in future research, by identifying optimal administration strategies of SB, as well as investigating if different phases of the MC impacted exercise performance, however this is still unknown. Methods: In a double-blind, randomised, placebo-controlled trial, six eumenorrheic female athletes will complete four all-out 30-second sprints on the Wattbike, each separated by a 5-minute recovery period after receiving either 0.3g/kg body mass (BM) of SB or a placebo containing plain flour in enteric coated capsules. Performance variables collected across the duration of the experimental trials are, rate of perceived exertion (RPE), peak power output (PPO), relative peak power (RPP), heart rate (HR), anaerobic capacity (AC), and fatigue index (FI). Experimental trials will be performed in each of the following two phases of a participant’s individually characterised MC: (i) the follicular phase and (ii) the luteal phase. MC phase will be determined by using a set of home ovulation strips for the whole duration of the study. In order to control any dietary variables, participants are asked to record a 24-hour food diary for the days prior to exercise testing and are encouraged to replicate identical food and fluid intake on the day prior to experimental testing to ensure a similar metabolic state. The development of this study in this area of research could greatly enhance our understanding of how the MC and the ingestion of SB may impact female athletes and performance outcomes. Furthermore, this study would provide valuable insights into the potential impact of different MC phases on athletes and help optimise their training and performance strategies.

Does upper body static stretching in warm up effect repeated sprint ability in boxers?

Boxing is a high intensity intermittent sport consisting of multiple 2 or 3 minute rounds. For a boxer to win, they must perform a higher quantity of strikes on their opponent. The mechanics of a punch draws power from the feet and lower body via rotation and ground force generation, however, the action still utilises the upper body predominantly (Beattie &amp; Ruddock. 2022, J Strength Cond Res, 36, 2957-2969). The ability to perform repeated bouts of maximal effort with limited recovery may be indicative of success. Static ‘developmental’ stretches are suggested by England Boxing for use in post-exercise cool-down, although without detailed justification (England Boxing. 2023, Level 1 coaching handbook). Static stretching in warm-up has also been explored in other practices with mixed results (Haddad et al; 2014, J Strength Cond Res, 28, 140-146) and is yet to be researched for boxing. Arm-cranking has previously been used as a sport-specific measurement for upper body power output in amateur boxers. (Venckunas et al; 2022, J Strength Cond Res, 36, 717-722). The aim of this study is to investigate the effects of static stretching in warm-up on upper-body repeated maximal effort arm crank ability in boxers. It is hypothesised that a static stretching intervention in warm-up will improve boxers' repeated maximal effort ability. For this repeated-measures design, a sample of male “development” level boxers (England Boxing. 2023, England Boxing Development Championship) will be recruited. Following institutional ethical approval, participants will partake in 2 sessions where they will perform 7 repetitions of 6s arm-crank maximal-effort sprints separated by 13 s recovery. This time duration simulates the activity:recovery ratio and intensity of a boxing bout (Davis et al., 2017, J Strength Cond Res). Peak power (W) will be measured in each sprint, with fatigue index (FI%) and decrement score calculated to assess participant fatigue over the 7 maximal efforts. There will be a light 1-minute sport-specific warm-up (Shadowboxing) before the first session, then a week later the participants repeat the warm up but with an additional stretching intervention. The static stretches include 2 repetitions of 30 s upper-body focussed static stretches until mild discomfort (upper limbs and shoulders, back and chest) (Liguori et al., 2021, ACSM’s guidelines for exercise testing and prescription). Peak power, FI% and decrement score will be compared Pre-Post stretching intervention using paired samples t-test and Cohen’s d effect size using SPSS.

Evaluating and correlating asphalt binder and mixture fatigue properties considering aging conditions

Asphalt fatigue cracking is a critical distress type for flexible pavement. This study utilized the state of practice binder and mixture cracking tests and parameters to investigate how asphalt binders’ and mixtures’ fatigue performance vary between the different mix designs and evaluate their changes with aging. The potential relationships between the measured binder properties and mixture performance were also explored. Five asphalt mixtures with disparate mix designs were evaluated and three different aging conditioning levels were conducted. The binder tests include the traditional time and frequency sweep and linear amplitude sweep test, while the mixture evaluations include the semi-circular bending and cyclic fatigue test. The results indicate that the different fatigue parameters from the tests can evaluate and rank the mixes differently. The correlation analysis using the Spearman correlation coefficient shows that the mixture cracking parameters that are more predominant by asphalt mixture’s flexibility/brittleness show strong correlations (Spearman coefficient larger than 0.8) with binder cracking indices. The LAS fatigue life-related parameters generally do not correlate well with mixture fatigue indices (Spearman coefficient smaller than 0.6). Furthermore, a prediction model to estimate asphalt mixture’s fatigue performance was developed based on linear regression and Artificial Neural Network (ANN) approach, which only requires the mix design info. and binder fatigue property as the inputs, significantly reducing the time and eliminating the effort in preparing and testing the asphalt mixture specimen for mixture fatigue performance measurement.

Anaerobic Abilities Students Using Indirect Tests: Fatigue Index and Peak Power

Background: Most human movements are supported by its functional capabilities of the anaerobic type, which is dominated by submaximal and maximal sports activities performed in a short time. Functional capabilities of the anaerobic type of man participate in most of his movement activities. Conditioned on adequate and extremely good interaction and functioning of the cardiovascular and respiratory systems, morphological status, metabolic processes, muscle structure, nutritional status, physical activity, etc. Purpose: The research was conducted in the conditions of the so-called field testing with the primary goal of assessing the acute state of anaerobic abilities of physical and sports students, by calculating the fatigue index (FI). Methods: The sample included 80 students of Physical and Sports Education, different geographical regions, average weight 77.88±8.49kg, age 20-23 years. The Running Anaerobic Sprint Test (RAST) was used to assess FI, and the basic statistical parameters were calculated. Results: The average value of the student's leg power is 573.89 watts (378.42 watts vs. 817.99watts), and the recorded average (FI) of 8.35 watts/sec (3.97watts/sec. vs. 16.93watts/sec.). Conclusions: The obtained results confirmed the average values of anaerobic capacity which are suitable for the examined population of subjects, while the maximal the value of FI suggests a weaker state of the anaerobic capacity of the individuals (less tolerance to lactates).

Neuromechanical Differences between Pronated and Supinated Forearm Positions during Upper-Body Wingate Tests.

Arm-cycling is a versatile exercise modality with applications in both athletic enhancement and rehabilitation, yet the influence of forearm orientation remains understudied. Thus, this study aimed to investigate the impact of forearm position on upper-body arm-cycling Wingate tests. Fourteen adult males (27.3 ± 5.8 years) underwent bilateral assessments of handgrip strength in standing and seated positions, followed by pronated and supinated forward arm-cycling Wingate tests. Electromyography (EMG) was recorded from five upper-extremity muscles, including anterior deltoid, triceps brachii lateral head, biceps brachii, latissimus dorsi, and brachioradialis. Simultaneously, bilateral normal and propulsion forces were measured at the pedal-crank interface. Rate of perceived exertion (RPE), power output, and fatigue index were recorded post-test. The results showed that a pronated forearm position provided significantly (p < 0.05) higher normal and propulsion forces and triceps brachii muscle activation patterns during arm-cycling. No significant difference in RPE was observed between forearm positions (p = 0.17). A positive correlation was found between seated handgrip strength and peak power output during the Wingate test while pronated (dominant: p = 0.01, r = 0.55; non-dominant: p = 0.03, r = 0.49) and supinated (dominant: p = 0.03, r = 0.51; don-dominant: p = 0.04, r = 0.47). Fatigue changed the force and EMG profile during the Wingate test. In conclusion, this study enhances our understanding of forearm position's impact on upper-body Wingate tests. These findings have implications for optimizing training and performance strategies in individuals using arm-cycling for athletic enhancement and rehabilitation.

P‐33: Differences in Visual Comfort of Smartphones between Comfortable and Uncomfortable Luminance

Differences in visual comfort between comfortable and uncomfortable luminance were explored on a smartphone. The results revealed that tiny changes in CFF and microsaccade parameters (pupil diameter, amplitude, and peak velocity) were presented at the comfortable luminance, inducing less eye discomfort. Particularly, CFF is an effective indicator of visual comfort and fatigue.