Central Fatigue

This study aimed to investigate the effects of central and peripheral fatigue on the golf swing, focusing on how these two types of fatigue influence movement variability and movement smoothness during performance. Methods: This semi-experimental study included 30 female students (aged 20-35 years) with normal vision from Tehran City. Participation was voluntary, with informed consent obtained, and participants were stratified into three groups based on inclusion criteria: Central fatigue, peripheral fatigue, and a non-intervention control group. First, a demographic questionnaire was administered. Central and peripheral fatigue were assessed using the visual analog scale (VAS) and the Borg Scale, while motor coordination parameters were evaluated using qualisys motion analysis software. Results: Repeated-measures ANOVA revealed a statistically significant difference in mean motor coordination variability among the three groups in the post-test (P=0.001). Post-hoc comparisons showed that the non-intervention group had significantly lower motor coordination variability than both the central (P=0.001) and peripheral fatigue (P=0.001) groups. Additionally, motor coordination in the central fatigue group was significantly lower than in the peripheral fatigue group (P=0.001). Further analysis indicated that the non-intervention group exhibited a lower mean jerk (i.e. smoother movement) compared to both the central and peripheral fatigue groups (P=0.001). Conclusion: The findings provide empirical evidence that central and peripheral fatigue differentially impair golf swing execution, with distinct effects on movement variability and smoothness.

Background Sports nutritional supplements containing branched-chain amino acids (BCAA) have been widely reported to improve psychological and biological aspects connected to central fatigue and performance in endurance exercise, although the topic is still open to debate. The aim of the present study was to determine whether the intake of a commercially available BCAA-based supplement, taken according to the manufacturer’s recommendations, could affect the rating of perceived exertion (RPE) and performance indexes at the beginning (1d) and end of a 9-week (9w) scheduled high intensity interval training program, with an experimental approach integrating the determination of psychometric, performance, metabolic and blood biochemical parameters. Methods This was a randomized double-blind placebo-controlled study. Thirty-two untrained, healthy young adults (20 males and 12 female) were enrolled. A high-intensity endurance cycling (HIEC) test was used to induce fatigue in the participant...

Caffeine has been shown to enhance exercise performance and capacity. The mechanisms remain unclear but are suggested to relate to adenosine receptor antagonism, resulting in increased central motor drive, reduced perception of effort, and altered peripheral processes such as enhanced calcium handling and extracellular potassium regulation. Our aims were to investigate how caffeine (i) affects knee extensor PCr kinetics and pH during repeated sets of single-leg knee extensor exercise to task failure and (ii) modulates the interplay between central and peripheral neural processes. We hypothesized that the caffeine-induced extension of exercise capacity during repeated sets of exercise would occur despite greater disturbance of the muscle milieu due to enhanced peripheral and corticospinal excitatory output, central motor drive, and muscle contractility. Nine healthy active young men performed five sets of intense single-leg knee extensor exercise to task failure on four separate occa...

Although elbow extensors (EE) have a great role in cross‐country skiing (XC) propulsion, previous studies on neuromuscular fatigue in long‐distance XC have investigated only knee extensor (KE) muscles. In order to investigate the origin and effects of fatigue induced by long‐distance XC race, 16 well‐trained XC skiers were tested before and after a 56‐km classical technique race. Maximal voluntary isometric contraction (MVC) and rate of force development (RFD) were measured for both KE and EE. Furthermore, electrically evoked double twitch during MVC and at rest were measured. MVC decreased more in KE (−13%) than in EE (−6%, P = 0.016), whereas the peak RFD decreased only in EE (−26%, P = 0.02) but not in KE. The two muscles showed similar decrease in voluntary activation (KE −5.0%, EE −4.8%, P = 0.61) and of double twitch amplitude (KE −5%, EE −6%, P = 0.44). A long‐distance XC race differently affected the neuromuscular function of lower and upper limbs muscles. Specifically, alth...

The purpose of this study was to examine the effects of ten days high-intensity training on human PBMC DNA damage. 20 subjects were randomly assigned into two groups (n=10). The intervention group was performing daily cycle training for ten days, while the control group did not exercise at all. Blood samples were analysed the day before training starts in the morning after the last session and after four days of recovery. Daily training was quantified using the TRIMP the RPE scale and lactate concentration. Also the differences in the overall well-being was measured using the MDBF Two-way ANOVA showed no significant differences between the groups in DNA damage. Results have shown that the stress, initiated by the training was not represented in the PBMC.

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The aim of the present study was to investigate the role of maturation on the etiology of neuromuscular fatigue induced by repeated maximal voluntary isometric contractions (MVIC). Methods: Nine prepubertal boys (9.9  1.3 yr.), eight male adolescents (13.6  1.3 yr.) and eleven men (23.4  3.0 yr.) performed a series of repeated isometric MVICs of the knee extensors until the MVIC torque reached 60% of its initial value. Magnetic stimulations were delivered to the femoral nerve every five MVICs to follow the course of voluntary activation level (VA) and the potentiated twitch torque (Qtwpot). Results: Task failure was reached after 52.9  12.7, 42.6  12.5 and 26.6  6.3 repetitions in boys, adolescents and men, respectively. VA remained unchanged in men whereas it decreased significantly and similarly in boys and adolescents (p<0.001). In contrast, Qtwpot remained unchanged in boys and decreased significantly less in adolescents than adults (p<0.05). Conclusions: Children and adolescents experience less peripheral and more central fatigue than adults. However, adolescents experience more peripheral fatigue than children for a comparable amount of central fatigue. This finding supports the idea that the tolerance of the central nervous system to peripheral fatigue could increase during maturation.

Prolonged exercise, particularly in endurance sports, is known to exacerbate both central and peripheral fatigue, negatively impacting neuromuscular function. Dehydration accelerates these effects, impairing the ability of muscles to generate force and diminishing motor output from the central nervous system. This study investigates the role of fluid ingestion in mitigating the decline in neuromuscular function during extended exercise. Twenty healthy, recreationally active male participants aged 18-30 years completed two exercise trials-one with fluid ingestion and the other without. Participants cycled for two hours at 65% of their maximum heart rate in both hydrated (HYD) and dehydrated (DEHYD) conditions. Neuromuscular function was assessed using maximal voluntary contraction (MVC), electromyography (EMG), and the central activation ratio (CAR). Results showed significant declines in MVC, EMG, and CAR in the DEHYD condition compared to the HYD condition. Body mass loss and urine specific gravity also indicated greater dehydration in the DEHYD trial. Fluid ingestion was found to preserve neuromuscular function by maintaining blood volume, electrolyte balance, and thermoregulation. This study highlights the critical importance of hydration strategies for athletes, as fluid ingestion significantly reduces both central and peripheral fatigue during prolonged exercise, ultimately improving endurance performance.

The objective of this study was to evaluate whether an adapted Hill-type model of muscle energetics could account for the relatively high energy turnover observed during low frequency isometric Neuromuscular Electrical Stimulation (NMES). A previously validated Hill-based model was adapted to estimate the energy consumption due to muscle activation, force maintenance and internal shortening of the muscle during isometric NMES. Quadriceps muscle model parameters were identified for 10 healthy subjects based on the experimentally measured torque response to isometric stimulation at 8 Hz. Model predictions of torque and energy consumption rates across the stimulation range 1-12 Hz were compared with experimental data recorded from the same subjects. The model provided estimates in close agreement with the experimental values for the group mean energy consumption rate across the frequency range tested, (R adj 2 = 0.98), although prediction of individual data points for all frequencies and all subjects was more variable, (R adj 2 = 0.70). The model suggests that approximately onethird of the energy between 4 and 6 Hz is due to shortening heat. The model provides a means of identifying optimal therapeutic stimulation patterns for sustained incremental oxygen uptake at minimum torque output for a given muscle and provides insight into the energetic components involved.

Background Sports nutritional supplements containing branched-chain amino acids (BCAA) have been widely reported to improve psychological and biological aspects connected to central fatigue and performance in endurance exercise, although the topic is still open to debate. The aim of the present study was to determine whether the intake of a commercially available BCAA-based supplement, taken according to the manufacturer’s recommendations, could affect the rating of perceived exertion (RPE) and performance indexes at the beginning (1d) and end of a 9-week (9w) scheduled high intensity interval training program, with an experimental approach integrating the determination of psychometric, performance, metabolic and blood biochemical parameters. Methods This was a randomized double-blind placebo-controlled study. Thirty-two untrained, healthy young adults (20 males and 12 female) were enrolled. A high-intensity endurance cycling (HIEC) test was used to induce fatigue in the participant...

This study aimed to explore neuromuscular fatigue and recovery profiles in individuals with intellectual disability (ID) after exhausting submaximal contraction. Methods: Ten men with ID were compared to 10 men without ID. The evaluation of neuromuscular function consisted in brief (3 s) isometric maximal voluntary contraction (IMVC) of the knee extension superimposed with electrical nerve stimulation before, immediately after, and during 33 min after an exhausting submaximal isometric task at 15% of the IMVC. Force, voluntary activation level (VAL), potentiated resting twitch (Ptw), and electromyography (EMG) signals were measured during IMVC and then analyzed. Results: Individuals with ID developed lower baseline IMVC, VAL, Ptw, and RMS/Mmax ratio (root-mean-square value normalized to the maximal peak-to-peak amplitude of the M-wave) than controls (p < 0.05). Nevertheless, the time to task failure was significantly longer in ID vs. controls (p < 0.05). The 2 groups presented similar IMVC decline and recovery kinetics after the fatiguing exercise. However, individuals with ID presented higher VAL and RMS/Mmax ratio declines but lower Ptw decline compared to those without ID. Moreover, individuals with ID demonstrated a persistent central fatigue but faster recovery from peripheral fatigue. Conclusion: These differences in neuromuscular fatigue profiles and recovery kinetics should be acknowledged when prescribing training programs for individuals with ID.

This paper is concerned with developing a force-generating model of electrically stimulated muscle under non-isometric condition. Hill-based muscle models have been the most popular structure. This type of muscle model was constructed as a combination of different independent blocks (i.e., activation dynamics, force-length and force-velocity relations, and series elastic element). The model assumes that the force-length and the force-velocity relations are uncoupled from the activation dynamics. However, some studies suggest that the shapes of the active force-length and the active force-velocity curves change with the level of the activation. Moreover, the "active state" block of the Hill-type model has no physical interpretation. To overcome the limitation of the Hill-type model, we used the multilayer perceptron (MLP) with back-propagation learning algorithm and Radial Basis Function (RBF) network with stochastic gradient learning rule for muscle modeling, where the stimulation signal, muscle length, velocity of length perturbation, and past measured or predicted force constitute the input of the neural model, and the predicted force is the output. Two modes of network operation are of interest: a time-varying network which allows updating the parameters of network to continue after convergence, and a time-invariant neural network with parameters fixed after convergence. The results show that time-varying and time-invariant neural networks would be able to track the muscle force with accuracy up to 99.5% and 95%, respectively. In addition, the results show that the accuracy of muscle force prediction depends on the structure of neural network. The prediction accuracy of RBF network after 1000 training epochs is higher than that of MLP network after 5000 training epochs.

Caffeine, an adenosine receptor antagonist, has shown to improve performance in normal ambient temperature, presumably via an effect on dopaminergic neurotransmission through the antagonism of adenosine receptors. However, there is very limited evidence from studies that administered caffeine and examined its effects on exercise in the heat. Therefore, we wanted to study the effects of caffeine on performance and thermoregulation in high ambient temperature. Eight healthy trained male cyclists completed two experimental trials (in 30°C) in a double-blind-randomized crossover design. Subjects ingested either placebo (6 mg/kg) or caffeine (6 mg/kg) 1 h prior to exercise. Subjects cycled for 60 min at 55% W max , immediately followed by a time trial to measure performance. The significance level was set at p \ 0.05. Caffeine did not change performance (p = 0.462). Rectal temperature was significantly elevated after caffeine administration (p \ 0.036). Caffeine significantly increased B-endorphin plasma concentrations at the end of the time trial (p = 0.032). The present study showed no ergogenic effect of caffeine when administered 1 h before exercise in 30°C. This confirms results from a previous study that examined the effects of caffeine administration on a short (15 min) time trial in 40°C. However, caffeine increased core temperature during exercise. Presumably, the rate of increase in core temperature may have counteracted the ergogenic effects of caffeine. However, other factors such as interindividual differences in response to caffeine and changes in neurotransmitter concentrations might also be responsible for the lack of performance improvement of caffeine in high ambient temperature.

Objectives: To de®ne motor cortical excitability changes occurring at various times after non-fatiguing bimanual exercise of the index ®ngers. Methods: Twenty healthy right-handed subjects were studied with transcranial magnetic stimulation (TMS) of the right non-dominant hemisphere. They performed regular (3±4/s) repetitive opening±closing bilateral movements of the index ®nger onto the thumb. Motor evoked potentials (MEPs) of the left ®rst dorsal interosseus (FDI) and rate of the repetitive ®nger movements were determined (1) before exercise, (2) immediately following 3 exercise periods of 30, 60 and 90 s, and (3) over a subsequent 30 min rest period. Results: Rate of movement did not show signi®cant change during any of the exercise periods but did increase signi®cantly when tested after 15 min of rest. MEPs immediately after 30 and 60 s of exercise were facilitated whereas MEPs after 90 s of exercise did not differ from baseline measures. MEP amplitudes were signi®cantly increased after rest of approximately 15 min compared to the baseline MEPs. In contrast, motor potentials evoked by peripheral nerve stimulation were unchanged throughout the experimental test periods. Conclusions: Motor cortical excitability relating to an intrinsic ®nger muscle (FDI) was facilitated beginning 15 min after a brief period of non-forceful, repetitive activity of that muscle. This delayed facilitation of motor cortex after exercise may represent a form of short-term potentiation of motor cortical excitability.

Ergogenic aids are the administration of certain substances, blood doping, genetic engineering, modification of exercise equipment, and the provision of natural materials such as plants to increase performance. This study aimed to determine the effect of consumption of Moringa oleifera leaves combined with aerobic exercise on VO 2 Max, Lactate Threshold, and muscle endurance. This study used an experimental methodology with a randomized pre-test and post-test comparison group design. Sixteen taekwondo athletes participated as samples in this study. The samples were split into two groups: the experimental group that received treatment including both aerobic exercise and the consumption of Moringa oleifera leaves, and the control group that received only aerobic exercise. This study consisted of four days of aerobic exercise each week for six weeks. The aerobic activity prescribed was a 30-minute session of vigorous running every day while Moringa oleifera leaves were consumed. Our current results showed that the consumption of leaf extract of Moringa oleifera increased VO 2 max versus control. In addition, Moringa oleifera increased lactate threshold shown at heart rate on turn point which increased from 173.5 ± 1.77 on the pre-test to 176.625 ± 1.51 beats/ minute on post-test. This result indicated that Moringa oleifera increases VO 2 max and Lactate threshold. Furthermore, our current results showed that the gain of the Moringa oleifera group was higher than the control in the push-up test, sit-up test, and wall sit test, respectively. This result indicated Moringa oleifera's ability to increase muscle endurance capacity. This current study indicated that Moringa oleifera leaves have the potential to increase human performance through their ability to increase VO 2 max, lactate threshold, and muscle endurance capacity.

This study determined the contribution of supraspinal fatigue and contractile properties to the age difference in neuromuscular fatigue during and recovery from a low-intensity sustained contraction. Cortical stimulation was used to evoke measures of voluntary activation and muscle relaxation during and after a contraction sustained at 20% of maximal voluntary contraction (MVC) until task failure with elbow flexor muscles in 14 young adults (20.9 ± 3.6 yr, 7 men) and 14 old adults (71.6 ± 5.4 yr, 7 men). Old adults exhibited a longer time to task failure than the young adults (23.8 ± 9.0 vs. 11.5 ± 3.9 min, respectively, P &lt; 0.001). The time to failure was associated with initial peak rates of relaxation of muscle fibers and pressor response ( P &lt; 0.05). Increments in torque (superimposed twitch; SIT) generated by transcranial magnetic stimulation (TMS) during brief MVCs, increased during the fatiguing contraction ( P &lt; 0.001) and then decreased during recovery ( P = 0.02)....

Paired associative stimulation (PAS) is a non-invasive stimulation method developed to induce bidirectional changes in the excitability of the cortical projections to the target muscles. However, very few studies have shown an association between changes in motor evoked potentials (MEP) after PAS and behavioral changes in healthy subjects. In the present study we hypothesized that the functional relevance of PAS can be seen during fatiguing exercise, since there is always a central contribution to the development of fatigue. Transcranial magnetic stimulation was applied over the motor cortex to measure changes in the MEPs of the soleus muscle before and after PAS. Furthermore, fatigue resistance was tested during 15 s sustained maximal isometric contractions before and after PAS. On average, fatigue resistance did not change after PAS, however the change in excitability correlated significantly with the change in fatigue resistance. Discussion: Functionality of PAS intervention was not demonstrated in this study. However, the observed relationship between excitability and fatigue resistance suggests that PAS might have affected central fatigue during short maximal contractions.

Paired associative stimulation (PAS) is a non-invasive stimulation method developed to induce bidirectional changes in the excitability of the cortical projections to the target muscles. However, very few studies have shown an association between changes in motor evoked potentials (MEP) after PAS and behavioral changes in healthy subjects. In the present study we hypothesized that the functional relevance of PAS can be seen during fatiguing exercise, since there is always a central contribution to the development of fatigue. Transcranial magnetic stimulation was applied over the motor cortex to measure changes in the MEPs of the soleus muscle before and after PAS. Furthermore, fatigue resistance was tested during 15 s sustained maximal isometric contractions before and after PAS. On average, fatigue resistance did not change after PAS, however the change in excitability correlated significantly with the change in fatigue resistance. Discussion: Functionality of PAS intervention was not demonstrated in this study. However, the observed relationship between excitability and fatigue resistance suggests that PAS might have affected central fatigue during short maximal contractions.

The interpolated twitch technique (ITT) is the gold standard to assess voluntary activation and central fatigue. Yet, its validity has been questioned. Here we studied how peripheral fatigue can affect the ITT. Repeated contractions at submaximal frequencies were produced by supramaximal electrical stimulations of the human adductor pollicis muscle in vivo and of isolated rat soleus fiber bundles; an extra stimulation pulse was given during contractions to induce a superimposed twitch. Human muscles fatigued by repeated 30-Hz stimulation trains (3 s on-1 s off) showed an ~80% reduction in the superimposed twitch force accompanied by a severely reduced EMG response (M-wave amplitude), which implies action potential failure. Subsequent experiments combined a less intense stimulation protocol (1.5 s on-3 s off) with ischemia to cause muscle fatigue, but which preserved M-wave amplitude. However, the superimposed twitch force still decreased markedly more than the potentiated twitch for...

The aim of this study was to investigate the effect of central and peripheral fatigue on motor coordination in collegiate athletes. The population consisted of all the students of Faculty of Physical Education and Sports Sciences of University of Tehran and 24 subjects were selected by convenience sampling method. They were randomly divided into two groups (central and peripheral fatigue) depending on the type of fatigue after a bimanual motor coordination pretest. Bimanual motor coordination posttest was performed after the intervention for 12 hours. In order to investigate the differences between the groups, independent t test and to determine differences within a group, dependent t test were used with the significance level of P≤0.05. Results showed that the mean time to complete the task and the timing error in central (P=0.004) and peripheral (P=0.0001) fatigue groups significantly increased compared with the pretest. Also, a significant difference in bimanual motor coordination between the two groups was observed in posttest (P=0.006). According to the results, it is suggested that athletes' training and working programs should be planned so that they include exercises to increase mental stamina along with physical exercises and that the athletes can provide their optimal performance in different conditions.

The aim of this study was to investigate the effect of neurofeedback training on sleep quality and psychological skills of athletes with psychophysiological approach. The research method was semi-experimental and application with pretest and posttest design and a control group. 31 athletes who were members of a sport team gained the criteria to enter the study. They were randomly assigned to experimental and control groups and the experimental group received neurofeedback treatment. The neurofeedback training lasted 3 sessions a week, 45 min. each session for 2 months. This protocol was performed in a bipolar manner at C4-CZ points. Pittsburgh Sleep Quality Index (PSQI) was used to extract sleep quality profile and OMSAT-3 and Elisa method were used to assess psychophysiological stress of participants. Covariance analysis and dependent t test were used to analyze the data. The results suggested that neurofeedback training can influence to balance stress and to improve sleep quality of athletes which greatly affects their performance.

Objective Upper limb neurodynamic tests are used to evaluate the mechanical sensitivity of the peripheral nerves. However, very little is known about the reliability of upper limb neurodynamic tests, especially for the radial and ulnar nerves. This study aimed to evaluate the reliability of neurodynamic tests of the upper extremities to test median, radial, and ulnar nerves. Materials & Methods In this observational cross-sectional study, 25 asymptomatic subjects aged 19-45 years participated. They were selected using simple non-random sampling. Then two examiners performed the neurodynamic tests on them on two successive days. The goal was to assess the reliability of median, radial, and ulnar neurodynamic tests. During the neurodynamic tests, the participants reported the initial stretching pain and the moment of submaximal pain (substantially obvious pain) in related areas of the nerve distribution, including the anterior side of the elbow and forearm for the median nerve, posterolateral aspect of the elbow and forearm for radial nerve, and medial side of elbow and forearm for the ulnar nerve. At the starting point of painful stretching and the submaximal pain, the angle of elbow extension (for median and radial nerve tests) and shoulder abduction angle (for ulnar nerve test) were measured using a mechanical goniometer. The range between these two points was used to analyze the reliability. The intraclass correlation coefficient (ICC) and the standard error of measurement (SEM) were calculated to examine the relative and absolute reliability, respectively. Using t-test, the difference in the mean of the measurements was calculated. Results No significant difference was found between the mean measurements of the two testers in intra-session and inter-session reliability. For examiners 1 and 2, was obtained 0.94 (SEM:2 ο) and 0.89 (SEM:2.85 ο) for the median nerve, 0.56 (SEM:6.36˚) and 0.93 (SEM:1.82 ο) for radial nerve, and 0.42 (SEM:3.27 ο) and 0.79 (SEM:1.42 ο) for the ulnar nerve. Inter-tester intra-session reliability was obtained at 0.84 (SEM: 3.44 ο), 0.54 (SEM: 6.1 ο), and 0.55 (SEM: 2.75 ο), respectively, for median, radial, and ulnar nerves. Inter-tester inter-session reliability was obtained at 0.97 (SEM:1.43 ο), 0.69 (SEM:5.06 ο), and 0.51 (SEM: 2.8ο), respectively, for median, radial, and ulnar nerves. Conclusion The upper limb neurodynamic tests and measurement of the range between the onset of stretching pain and the point of submaximal pain have moderate to excellent reliability. Therefore, these clinical tests can be used in diagnostic evaluations and treatment interventions. Also, the median nerve neurodynamic test has higher relative reliability than radial and ulnar nerve neurodynamic tests.

This study sought to determine whether afferent feedback associated with peripheral muscle fatigue inhibits central motor drive (CMD) and thereby limits endurance exercise performance. On two separate days, eight men performed constant-load, single-leg knee extensor exercise to exhaustion (85% of peak power) with each leg (Leg1 and Leg2). On another day, the performance test was repeated with one leg (Leg1) and consecutively (within 10 s) with the other/contralateral leg (Leg2-post). Exercise-induced quadriceps fatigue was assessed by reductions in potentiated quadriceps twitch-force from pre- to postexercise (ΔQtw,pot) in response to supramaximal magnetic femoral nerve stimulation. The output from spinal motoneurons, estimated from quadriceps electromyography (iEMG), was used to reflect changes in CMD. Rating of perceived exertion (RPE) was recorded during exercise. Time to exhaustion (∼9.3 min) and exercise-induced ΔQtw,pot (∼51%) were similar in Leg1 and Leg2 ( P &gt; 0.5). In th...

Background Sports nutritional supplements containing branched-chain amino acids (BCAA) have been widely reported to improve psychological and biological aspects connected to central fatigue and performance in endurance exercise, although the topic is still open to debate. The aim of the present study was to determine whether the intake of a commercially available BCAA-based supplement, taken according to the manufacturer’s recommendations, could affect the rating of perceived exertion (RPE) and performance indexes at the beginning (1d) and end of a 9-week (9w) scheduled high intensity interval training program, with an experimental approach integrating the determination of psychometric, performance, metabolic and blood biochemical parameters. Methods This was a randomized double-blind placebo-controlled study. Thirty-two untrained, healthy young adults (20 males and 12 female) were enrolled. A high-intensity endurance cycling (HIEC) test was used to induce fatigue in the participant...

The aim of this thesis was to directly test the key underpinnings of recent propositions for systems of central control of exercise regulation. Fatigue and exercise tolerance have traditionally been explained through peripheral mechanisms, such as excitation-contraction coupling failure and the inability to supply sufficient metabolic substrate to contracting muscle in order to meet increasing energy demand. More recently, models of central control, which are proposed to regulate exercise intensity in an anticipatory/feedforward manner, with the ultimate aim of avoiding physiological ‘catastrophe’, have received a great deal of attention. This thesis investigated several of the key requirements and mechanisms stated in these models. The central governor model (CGM) and teleoanticipation are stated to use a combination of prior experience and distance knowledge of an exercise bout to work in a feedforward manner, so that a pacing strategy is set before exercise commences which ensure...

This study aimed to compare the effect of two neurofeedback protocols on learning a pursuit tracking task. Forty-two volunteers placed in three groups of alpha-suppression, theta-enhancement and control. In the alpha-suppression group, alpha amplitude suppressed at C4 before the training, while the participants in the theta-enhancement intended to increase theta amplitude at Pz and immediately after training. After training session, the subjects participated in retention tests within 90 minutes, 24 hours, and one week intervals. The results showed that the alpha-suppression group performed better than control group in the first retention test. Nevertheless, this superiority was not significant in subsequent retention tests, where no difference was observed between the groups. These findings revealed that the inhibition of alpha range in the motor cortex and subsequent higher excitability can likely leave beneficial effects on learning a motor skill, even though the sustainability of...

Paired associative stimulation (PAS) is a non-invasive stimulation method developed to induce bidirectional changes in the excitability of the cortical projections to the target muscles. However, very few studies have shown an association between changes in motor evoked potentials (MEP) after PAS and behavioral changes in healthy subjects. In the present study we hypothesized that the functional relevance of PAS can be seen during fatiguing exercise, since there is always a central contribution to the development of fatigue. Transcranial magnetic stimulation was applied over the motor cortex to measure changes in the MEPs of the soleus muscle before and after PAS. Furthermore, fatigue resistance was tested during 15 s sustained maximal isometric contractions before and after PAS. On average, fatigue resistance did not change after PAS, however the change in excitability correlated significantly with the change in fatigue resistance. Discussion: Functionality of PAS intervention was not demonstrated in this study. However, the observed relationship between excitability and fatigue resistance suggests that PAS might have affected central fatigue during short maximal contractions.

Introduction: Fatigue is a gradual and cumulative process. This mindset is related to the lack of motivation to make any effort, as well as decreased efficiency, attentiveness, and, eventually, malfunction. Aim: The present study aims to investigate how mental and muscle fatigue affects spatial working memory. Method: The research method was quasi-experimental and was performed using the pretestposttest design. The participants in this study were 20 to 30 year old male students of Shahid Beheshti University of Tehran in 2021, of whom, 14 subjects were selected by convincing method as the sample using the G-Power approach and previous investigations. The Mental Fatigue Self-Assessment Scale, Corsi Block software, Stroop software, and the Monark Bike Ergometer were utilized. In addition, the repeated measurement analysis of variance test in SPSS-23 was used to analyze the data. Results: The results indicated that mental fatigue condition had a significant effect on working memory (P=0...

The central-governor model explains the mechanism of endurance exerciseinduced central fatigue, but high-intensity exercise-induced central fatigue has not been investigated yet. This study aimed to research how central fatigue during high-intensity intermittent pedaling alters the neural response, which results in Electroencephalography (EEG) recordings. Methods: We assessed neural response by measuring the alternation of brainwave spectral power during an intermittent high-intensity 60-minute exercise on an ergometer cycle. The cadences were changed every 10 minutes according to intermittent pattern altering (90-120-60-120-60-90 rpm). EEG was used to analyze altering brain function. Heart Rate (HR), Blood Lactate (BL), and Rating of Perceived Exertion (RPE) were measured after the change in cadences. Results: HR, BL, and RPE increased at a cadence of 120 rpm compared with 60 rpm on the ergometer cycle. The spectral power of EEG, according to cadence × brainwaves, significantly increased (P˂0.01) in the alpha and beta frequency ranges with a change in cadences between 60 rpm and 120 rpm. The spectral power of the EEG significantly increased (P˂0.01) over the whole frequency range from rest to warming (theta: 251%, alpha: 165%, beta: 145%) and significantly reduced in theta, alpha, and beta (theta: 176%, alpha: 142%, beta: 77%) (P≤0.01). Conclusion: High-intensity exercises (90 and 120 cadences) increased brain function, regardless of fatigue occurrence. High-intensity interval training (HIIT) led to altering the neural response. It would be required to investigate the usefulness of HIIT to treat some of the psychotic disorders.

The purpose of current study was to muscle efficiency changes during successful and unsuccessful trials in elite pistol shooters with role of quiet eye meditation. In causal comparative study, 20 elite male pistol shooters selected for this study with age range 20-30 years old. After five trials familiarization, participants performed 20 trials to target with available standard. Scores of ten were considered successful, and scores of less than ten were considered unsuccessful. Data were analyzed using paired t-test and Bootstrap. The results indicated that there was significant difference between biceps and triceps muscle activity in successful and unsuccessful trials, and participants had lower muscle activity in successful trials than unsuccessful trials. Also, Bootstrap results revealed that the quiet eye period mediates biceps and triceps muscle activity in successful and unsuccessful trials. Overall, the results of current study confirmed postural stability hypothesis that this is the determining factor during this period is an increase in postural stability, which leads to a reduction in "noise" in the motor system.Shooting skills with high perceptual / cognitive requirements and low mobility needs and is one of the sports that is highly dependent on the performance of the visual system, because target identification and tracking is largely dependent on the performance of the visual system.In the present study, the researcher intends to investigate the muscular efficiency and mediating role of the length of the stationary eye period in the electrical activity of biceps and triceps of skilled pistol shooters in successful and unsuccessful attempts.

This study aimed to investigate the effects of peripheral and central fatigues on depth perception error in students. The statistical population consisted of students in Khodabande city. 42 subjects (mean age of 16.88 ± 0.49 years) were selected by convenience sampling method. All subjects took depth perception pretest. Then, they were divided into the intervention and control groups. To produce peripheral fatigue (physical), the first group received physical fitness activity and the second group received mental activity to produce central (mental) fatigue. The third group did not perform any activity during the intervention period. The depth perception posttest was performed after the fatigue intervention. The results of one-way analysis of variance showed no significant differences in the pretest among the groups, but there was a significant difference in the posttest among the groups. LSD post hoc test results showed that central fatigue increased depth perception error in comparison with peripheral fatigue and no intervention (control group). But no significant differences were observed in depth perception error between peripheral fatigue and control groups. Paired t test results showed an increase in depth perception errors resulted from both types of fatigue and the lack of change in the control group. Overall, it can be concluded that central fatigue had an effective role in increasing students' depth perception error when compared to peripheral error. Therefore, coaches are advised to adopt appropriate conditions that reduce central fatigue.

1. Cognition 2. Cortical Excitability 3. Athletic Performance Introduction: Transcranial directcurrent stimulation is a nerve modulation technique that induces lowintensity direct current to brain cells that stimulate or inhibit spontaneous neural activity. In recent decades, the use of electrical stimulation has been used as an effective method to improve the cognitive, psychological, and physical performance of athletes. In this study, using metaanalysis, the effectiveness of extracranial electrical stimulation on optimizing athletes’ performance was investigated. Materials and Methods: The present study is a systematic review and meta-analysis research model. In the first phase of the study, all Persian and English studies on the effectiveness of Transcranial directcurrent stimulation on athlete’s performance were systematically reviewed (N=474), and among them, studies with metaanalysis criteria were reviewed by MetaAnalysis Basics and Applications (N=26). In the second stage, a...

Objective Dry cupping (DC) is widely used to improve sports performance. The purpose of this study was to examine the effect of DC on muscle strength, anaerobic power, cognitive function, and mood states of athletes. Methods In this counterbalanced quasi-experimental study with randomized crossover design, 12 male athletes participated. After signing a consent form, they randomly experienced two conditions (10 min of DC or no treatment) in two sessions one week apart. Muscle strength using a back and leg dynamometer, power anaerobic using the 30-second Wingate test, mood states using the Profile of Mood States questionnaire, and cognitive function using the Tower of London test were measured after intervention. Data were analyzed using paired sample t-test considering a significance level of 0.05. Results DC significantly increased mean power (t 11 =-2.625, p=0.024), with no significant effect on muscle strength (t 11 =1.106, P=0.293) and peak power (t 11 =-1.389, P=0.192). Treatment with DC had no significant effect on tension, depression, anger, vigor, confusion, calmness or happiness of subjects (P>0.05). In contrast, a significant decrease in mental fatigue (t 11 =2.209, P=0.049) and cognitive function (t 11 =-2.602, P=0.025) were observed after DC. Conclusion DC can improve mean anaerobic power and cognitive function, and reduce fatigue of the athletes.

This paper reports a research conducted to determine the changes in the electrical activity of the contralateral motor cortex of the brain that drives the maximum voluntary contraction (MVC) of right Adductor Pollicis muscle (APM) after fatigue. For this aim, the power changes of EEG signals after muscle fatigue were computed. EEG signals from the left motor cortical area (C3, FC3) in twenty-five subjects, simultaneously with the EMG from right Adductor Pollicis muscle (APM), before and after exercise-induced fatigue were recorded. The Root Mean Square (RMS) of the EEG bands (alpha, beta, and gamma) was calculated to determine the power changes of the EEG signals after right APM fatigue. The mean RMS of EEG bands were increased during MVC of fatigued right APM compared to the RMS value during relaxation before fatigue (p&lt;0.05). The RMS value was seen to be greatest in the beta band, and lowest in the gamma band. The observed increase in the RMS of EEG bands during MVC of fatigued...

Exercise at different cadences might serve as potential stimulus for functional adaptations of the brain, because cortical activation is sensitive to frequency of movement. Therefore, we investigated the effects of high (HCT) and low cadence training (LCT) on brain cortical activity during exercise as well as endurance performance. Cyclists were randomly assigned to low and high cadence training. Over the 4-week training period, participants performed 4 h of basic endurance training as well as four additional cadence-specific exercise sessions, 60 min weekly. At baseline and after 4 weeks, participants completed an incremental exercise test with spirometry and exercise at constant load with registration of electroencephalogram (EEG). Compared with LCT, a greater increase of frontal alpha/beta ratio was confirmed in HCT. This was based on a lower level of beta activity during exercise. Both groups showed similar improvements in maximal oxygen consumption and power at the individual a...

The present study was conducted to determine the effect of central and peripheral fatigue on balance and coordination of university athletes. The statistical population comprised of university athletes. The number of Samples were 24 persons (by convenience sampling) from which 12 were selected as central fatigue group and 12 as peripheral fatigue group. In order to measure the central fatigue, Flicker Fusion system was employed. Also, the cognitive load during the exams and Bruce test were used to induce central and peripheral fatigue, respectively. To measure the static balance in this study (the frequency distance of the body’s center of pressure in millimeters) and dynamic balance, plantar pressure distribution device and Y test were used, respectively. The pretests included static balance with double-leg, static balance with closed eyes, single-leg balance with dominant leg and open eyes, single-leg balance with dominant leg and closed eyes, Y balance test for dynamic balance, and double-leg and double-arm coordination test using Vienna based coordination meter device. The results of the multivariate analysis of variance (MANOVA) test showed that central fatigue has had significant effect on static balance with open eyes (p= 0.007), closed eyes (p= 0.001), and single-leg (0.046), anterior (p= 0.007), posterolateral (p= 0.001), and posteromedial (p= 0.046) dynamic balance, double-arm coordination task (p= 0.042), double-arm coordination error time (p= 0.00002), double-leg task completion time (p= 0.048), and also double-leg coordination error time (p= 0.001). Peripheral fatigue has also had significant effect on static balance with open eyes (p= 0.000001), closed eyes (p= 0.000106), and single-leg (p= 0.000005), anterior (p= 0.000009), posterolateral (p= 1.8052 E-9), and posteromedial (p= 0.000001) dynamic balance, double-arm coordination task (p= 0.001), double-arm coordination error time (p= 0.000005), double-leg task completion time (p= 8.5426 E-7), and also double-leg coordination error time (p= 5.3311 E-7). The difference between central and peripheral fatigue was significant in static balance (p= 0.007) and coordination (p= 0.0004) but non-significant in dynamic balance (p= 0.093). According to the results, the researchers suggest that studies be conducted on core exercises for mental stamina to by using them, athletes’ central fatigue and decreased performance be prevented.

Human muscle fatigue has been studied using a wide variety of exercise models, protocols and assessment methods. Based on the definition of fatigue as 'any reduction in the maximal capacity to generate force or power output', the different methods to measure fatigue are discussed. It is argued that reliable and valid measures must include either assessment of maximal voluntary contraction force or power, or the force generated by electrical stimulation. By comparing tetanic stimulation and maximal voluntary contraction force one may reveal whether fatigue is of central origin, or whether peripheral mechanisms are involved. Adequate use of twitch interpolation provides an even more sensitive measure for central fatigue. Indirect methods as endurance times and electromyography show variable responses during exercise and no close relationship to fatigue. Hence these methods are of limited value in measurement of human muscle fatigue. © 1997 Elsevier Science B.V.

Effects of activation frequency and force on low-frequency fatigue in human skeletal muscle. J. Appl. Physiol. 86(4): 1337-1346, 1999-No comparison of the amount of low-frequency fatigue (LFF) produced by different activation frequencies exists, although frequencies ranging from 10 to 100 Hz have been used to induce LFF. The quadriceps femoris of 11 healthy subjects were tested in 5 separate sessions. In each session, the force-generating ability of the muscle was tested before and after fatigue and at 2, ϳ13, and ϳ38 min of recovery. Brief (6-pulse), constant-frequency trains of 9.1, 14.3, 33.3, and 100 Hz and a 6-pulse, variable-frequency train with a mean frequency of 14.3 Hz were delivered at 1 train/s to induce fatigue. Immediately postfatigue, there was a significant effect of fatiguing protocol frequency. Muscles exhibited greater LFF after stimulation with the 9.1-, 14.3-, and variable-frequency trains. These three trains also produced the greatest mean force-time integrals during the fatigue test. At 2, ϳ13, and ϳ38 min of recovery, however, the LFF produced was independent of the fatiguing protocol frequency. The findings are consistent with theories suggesting two independent mechanisms behind LFF and may help identify the optimal activation pattern when functional electrical stimulation is used. muscle fatigue; electrical stimulation; excitation-contraction coupling 8750-7587/99 $5.00

Human muscle fatigue has been studied using a wide variety of exercise models, protocols and assessment methods. Based on the definition of fatigue as 'any reduction in the maximal capacity to generate force or power output', the different methods to measure fatigue are discussed. It is argued that reliable and valid measures must include either assessment of maximal voluntary contraction force or power, or the force generated by electrical stimulation. By comparing tetanic stimulation and maximal voluntary contraction force one may reveal whether fatigue is of central origin, or whether peripheral mechanisms are involved. Adequate use of twitch interpolation provides an even more sensitive measure for central fatigue. Indirect methods as endurance times and electromyography show variable responses during exercise and no close relationship to fatigue. Hence these methods are of limited value in measurement of human muscle fatigue. © 1997 Elsevier Science B.V.