Significant Fatigue Effect Research Articles

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.

Towards a more individualised assessment of post-training fatigue in young footballers

Despite improvements in training load and fatigue monitoring, fatigue status may adversely affect intrinsic risk factors, particularly in young footballers. This study aimed to better individualise the fatigue effects of a 75-min football training session in young elite male players.Eighteen players (15.6 ± 1.7 years) completed a test battery before and after a football training session. Assessments included capillary blood samples (HCO3−, lactate, pH), subjective ratings of muscle soreness and fatigue. Functional tests included 30 m field sprint, laboratory drop jump (DJ) and horizontal force-velocity (H-FvP). The k-means method was applied to the first two dimensions of principal component analysis of changes in the H-FvP and DJ tests.Football training resulted in significant physiological changes and functional impairments, in particular an increase in interlimb asymmetry in the DJ test. No significant fatigue effect was found on the H-FvP test data. However, confirming the interest of combining the two tests, cluster analysis revealed two subgroups: In the H-FvP test, Cluster 1 decreased in V‾0 (p < 0.001) and P‾max (p < 0.01), while Cluster 2 decreased in F‾0 (p < 0.001). In the DJ test, Cluster 1 decreased in mean velocity (p < 0.01), relative mean and maximum power (p < 0.01) during push-off, while Cluster 2 decreased in relative mean push-off force (p < 0.01) and increased in interlimb asymmetry during braking (p < 0.01).This study highlights the contribution and complementarity of the H-FvP and DJ tests to improve individual screening for fatigue-related functional changes in footballers. Extrapolated values from the H-FvP test led to the identification of two subgroups with opposite fatigue profiles. One subgroup showed increased interlimb asymmetry in DJ, indicating an increased risk of injury with fatigue. These findings highlight the need for individualised fatigue assessment in young footballers.

Effects of muscular and mental fatigue on spatiotemporal gait parameters in dual task walking in young, non-frail and frail older adults.

Dual-task (DT) walking is of great interest in clinical evaluation to evaluate frailty or cognitive declines in older adults. Frail older adults are known to adopt different walking strategy to overcome fatigue. However, no studies evaluated the effect of muscular or mental fatigue on dual-task walking strategy and the difference between frail and non-frail older adults. Evaluate the effect of mental and muscular fatigue on spatio-temporal parameters in dual-task walking in young, non-frail and frail older adults. 59 participants divided into 20 young (Y) (24.9 ± 3years old), 20 non-frail (NF) (75.8 ± 4.9years old) and 19 frail older adults (F) (81 ± 4.7years old) performed single-task (ST) walking, single-task cognitive (serial subtraction of 3), and dual-task (subtraction + walking) for 1min at their fast pace. Gait speed, step length, step length variability, stance and swing phase time, single and double support time, cadence, gait speed variability were recorded in single- and dual-task walking. The dual-task effect (DTE) was calculated as ((DT-ST)/ST)×100). Generalized linear mixed models (GLMM) were used to compare the effects of mental and muscular fatigue on gait and cognitive variables between the groups. The DTE walking parameters were worse in F compared to NF or Y but no significant effect of fatigue were highlighted except for swing time and single support time DTEs. The results were mitigated but a clear difference in dual-task spatio-temporal parameters was found between F and NF which brings hope into the capacity of DT to better reveal frailty.

Impacts of pulse conditions on endurance behavior of ferroelectric thin-film transistor non-volatile memory

In this work, the ferroelectric thin-film transistor (Fe-TFT) with polycrystalline-silicon (poly-Si) channel and HfZrO x gate dielectric is fabricated to study the characteristics of non-volatile memory (NVM). Significant threshold voltage (V TH) modulation can be achieved with low pulse voltages less than ±3.5 V and pulse widths within 1 μs. In order to achieve the NVM characteristics of low voltage and high speed operation, the impact of the program/erase (PRG/ERS) pulse voltage (V PRG/V ERS) and pulse width on endurance is a critical consideration. In the study of the pulse width effect on endurance, it can be observed that the V TH in PRG-state exhibits the wake-up effect at both short and long pulse widths. In addition, with the increase of pulse width, the V TH in the PRG-state exhibits significant fatigue effect and subthreshold swing (SS) degradation effect. For V TH in the ERS-state, the increase of the pulse width also exhibits the fatigue effect and the SS degradation effect, which is dominated by the SS degradation effect at long pulse widths. In the study of the pulse voltage effect on endurance, the increase of V PRG shows the imprint effect that the V TH in either PRG- or ERS-state reveals a decreasing trend. When the V ERS increases, the SS of the PRG- and ERS-states is degraded, and the fatigue effect of the PRG-state is enhanced. Moreover, the retention characteristics of poly-Si Fe-TFTs exhibit stable characteristics at both room temperature and 50 °C.

The Impact of Fatigue on the Sense of Local and Global Rhythmic Movement.

Efficient movement control and the mechanisms responsible for the sense of rhythm are still not fully understood. The purpose of this paper was to estimate the influence of fatigue on the sense of rhythm defined as specific order of movements and their rhythmic perception. It was examined in a holistic way, by analyzing both global and local aspects of the movement. Twenty adult participants (20.2 ± 0.4 years, ten females) took part in the experiment. The fatigue protocol was applied in four blocks, which consisted of 30-s consecutive jumping with 80% of maximal effort. Immediately after each fatigue block, the rhythm performance was evaluated in global and local tests. The global test was based on 45 continuous jumps and was divided into an assisted and an unassisted phase using the Optojump Next System. The local test was performed by bilateral tapping of lower limbs by means of the Vienna Test System. The hypothesis about the significant effect of fatigue on the sense of rhythm was falsified. In particular, we observed the lack of differences between global and local aspects of the movement. Moreover, female participants showed a better sense of rhythm than males. Regardless of the fatigue protocol, participants made larger errors with a lower movement frequency in local rhythmic tasks. The coefficient of variation showed that sex differences were only significant in the unassisted phase of the global rhythmic task. We suggest that movement variability metrics may provide additional information about the sense of rhythm, which should be explored more in future studies, not only dependent on fatigue.

A Further Exploration to Fatigue Indicator in PVT of China Air Traffic Controllers

Current study is aiming to find a more suitable behavioral fatigue index for Air Traffic Controllers(ATC) using PVT test and fatigue self-assessment questionnaires as tools, and gives these tests before and after ATC duty. Through PVT test and self-assessment questionnaire, this finding indicates hit rate and hit response time (the first 20% trials) of PVT can be potential fatigue index since we found first 2min hit response time of air traffic controller(ATC) after duty is significantly longer than before duty, together with the hit rate after duty is lower than before duty. 8 items in Stanford Sleepiness Scale(SSS) and Visual Analogy Scale(VAS) also show significant difference in self assessment on fatigue. ATCs think themselves are much more fatigue after duty than before duty.Besides, ATCs in regional control area show significant fatigue effect than those in terminal control area, indicating different work load in two different working areas. Those ATC work at night especially in midnight show much more significant fatigue than those work in the daytime showed by longer first 20% hit response time. In sum, hit rate and first 20% (first 2min) hit response time can be effective fatigue indexes of ATC.

Quantitative Analysis of Performance Recovery in Semi-Professional Football Players after the COVID-19 Forced Rest Period.

This study proposes the instrumental analysis of the physiological and biomechanical adaptation of football players to a fatigue protocol during the month immediately after the COVID-19 lockdown, to get insights into fitness recovery. Eight male semi-professional football players took part in the study and filled a questionnaire about their activity during the lockdown. At the resumption of activities, the mean heart rate and covered distances during fatiguing exercises, the normalized variations of mean and maximum exerted power in the Wingate test and the Bosco test outcomes (i.e., maximum height, mean exerted power, relative strength index, leg stiffness, contact time, and flight time) were measured for one month. Questionnaires confirmed a light-intensity self-administered physical activity. A significant effect of fatigue (Wilcoxon signed-rank test p < 0.05) on measured variables was confirmed for the four weeks. The analysis of the normalized variations of the aforementioned parameters allowed the distinguishing of two behaviors: downfall in the first two weeks, and recovery in the last two weeks. Instrumental results suggest a physiological and ballistic (i.e., Bosco test outcomes) recovery after four weeks. As concerns the explosive skills, the observational data are insufficient to show complete recovery.

Effects of Limb Dominance on Postural Balance in Sportsmen Practicing Symmetric and Asymmetric Sports: A Pilot Study

The current literature shows no consensus regarding the difference between the dominant leg (D-Leg) and the non-dominant leg (ND-Leg) in terms of postural control. This lack of consensus could stem from motor experience (i.e., symmetric or asymmetric motricity) and/or the physiological state induced by physical exercise. This study aimed to investigate the acute effects of fatiguing exercise on postural control when standing on the D-Leg and the ND-Leg, in athletes practicing symmetric (SYM) and asymmetric (ASYM) sports. Thirty healthy male participants were recruited and divided into two groups, (SYM n = 15) and (ASYM n = 15, on the basis of the motricity induced by the sport they practice. Monopedal postural control was assessed for the D-Leg and the ND-Leg before and after the fatigue period (which consisted of repeating squats until exhaustion). A force platform was used to calculate the spatio-temporal characteristics of the displacements of the center of foot pressure (COP). A significant fatigue effect was observed in both groups on the D-Leg and the ND-Leg for all the COP parameters. There was a tendency (p = 0.06) between the ASYM and SYM groups on the D-Leg, concerning the relative increase in the COP velocity in the frontal plane after the fatigue period. The fatigue condition disturbed postural control in both the SYM and ASYM groups on the D-Leg and ND-Leg. This disturbing effect related to fatigue tends to be more marked in athletes practicing asymmetric sports than in athletes practicing symmetric sports on the D-Leg.

Effect of training volume on footstrike patterns over an exhaustive run

BackgroundAlthough footstrike pattern (FP) may not be a factor influencing running performance, 11–75% of world-class distance runners use a non-rearfoot FP. However, little attention has been paid to describe the effect of running volume on FP changes when a runner is fatigued. Research questionDoes the training volume provide an adequate stimulus to mitigate FP changes during an exhaustive run in non-rearfoot, habitual minimalist footwear runners? MethodsThe objective of this study was to compare FP between non-rearfoot, habitual minimalist footwear runners with a moderate training volume (MT) and a high training volume (HT) during an exhaustive run on a motorized treadmill. Based on their weekly training volume (distance), twenty-eight runners were arranged into two groups paired by height and age. At the first visit, runners underwent a VO2max test to acquire their velocity for the exhaustive run. During the second visit, biomechanical and physiological analysis of the beginning and the end phase of the exhaustive run was done. ResultsThe frontal plane foot angle, the sagittal plane ankle angle at the initial contact (IC), and the foot eversion ROM showed a significant interaction effect (P < 0.05). Additionally, the sagittal plane footstrike angle, the frontal plane foot angle, the sagittal plane ankle angle, knee flexion angle at IC and foot eversion ROM showed a significant effect of fatigue (P < 0.05). Finally, the frontal plane foot angle, the sagittal plane footstrike angle, the sagittal plane ankle angle, and the knee flexion angle showed significant group effects (P < 0.05). SignificanceThe training volume affects the footstrike pattern of non-rearfoot, habitual minimalist footwear runners when they are fatigued. The highly trained runners maintained their ankle angle throughout the exhaustive running protocol, whereas the moderately trained group changed the frontal and sagittal plane characteristics of their footstrike pattern.

Quantifying Accelerometer-Based Tremor Features of Neuromuscular Fatigue in Healthy and Diabetic Adults

Neuromuscular fatigue affects workers' productivity and health, which is further deteriorated with chronic conditions such as type 1 diabetes (T1D). Enhanced physiological tremor, a key indicator of neuromuscular fatigue, shows great potential in detecting the onset of neuromuscular fatigue. This study aims to determine the feasibility of using a cost-effective wearable accelerometer-based microelectromechanical sensor to convey neuromuscular fatigue-related tremor information in healthy and T1D adults. 42 adults (22 healthy, 20 T1D), equipped with a finger and a wrist accelerometer, performed intermittent submaximal isometric handgrip fatigue exercises using a grip dynamometer. Motor variability feature, namely, Coefficient of Variation (CV), and motor complexity feature, namely approximate entropy (ApEn), were extracted from the force signal of dynamometer and from the finger and wrist tremor accelerometry signals and subjected to statistical analysis. First, significant positive correlations were found between tremor accelerometry and force signal in terms of motor variability and complexity features. Second, a three-way (fatigue phase: early, middle, late; gender: male, female; condition: healthy, T1D) analysis of variance resulted in a significant fatigue effect on both accelerometry and force measurements in terms of motor variability and complexity features. Apart from finger CV, no other features showed any gender or condition effects. These findings indicate that finger and wrist tremors measured by accelerometer-based sensors can retain the robustness of fatigue-related motor variability and complexity. Wrist tremor features were found to capture fatigue development across both healthy and diabetic males and females, thereby offering comparable fatigue detection and management in adults with chronic conditions.

Physiological indicators of task demand, fatigue, and cognition in future digital manufacturing environments

Abstract As Digital Manufacturing transforms traditionally physical work into more system-monitoring tasks, new methods are required for understanding people’s mental workload and prolonged capacity for focused attention. Many physiological measures have shown promise for detecting changes in cognitive state, and recent advances in sensor technology offer minimally-invasive ways to monitor our cognitive activity. Previous research in functional near-infrared spectroscopy, for example, has observed changes in cerebral hemodynamic response during periods of high demand within tasks. This work investigated the relationships among task demand, fatigue, and attention degradation in a sustained attention task, and their effect on heart rate, breathing rate, nose temperature and hemodynamic response in the prefrontal cortex and middle temporal gyrus. Analysis revealed a small but significant effect of fatigue on heart rate relative to baseline, breathing rate and hemodynamic response. Task demand had a small but significant effect on breathing rate and nose temperature, both relative to baseline, but no difference between levels of demand was observed in heart rate or hemodynamic response. Our results provide insight into what physiological data can tell us about cognitive state, ability to focus, and the impact of fatigue over time.

Electric control of exchange bias in multiferroic hexaferrite Ba0.4Sr1.6Mg2Fe12O22

Electric field reversal of large magnetization has been achieved in the multiferroic hexaferrite $\mathrm{B}{\mathrm{a}}_{0.4}\mathrm{S}{\mathrm{r}}_{1.6}\mathrm{M}{\mathrm{g}}_{2}\mathrm{F}{\mathrm{e}}_{12}{\mathrm{O}}_{22}$ with conical spin structures. The variation of magnetization depends on the sweeping rate of the applied electric field, leading to a significant fatigue effect. Such a slow dynamical behavior is attributed to the hysteresis magnetization process facilitated by the electric field. Moreover, the $M\text{\ensuremath{-}}H$ hysteresis loop can be manipulated by external electric fields, causing either a positive or negative exchange bias phenomenon. The role of the electric field acting as a bias magnetic field on the magnetic hysteresis loop is discussed in terms of the pinning of magnetic domains by conjugated ferroelectric domains.

Effects of Fatigue on the BTrackS Balance Test for Concussion Management

Fatigue has been shown to adversely affect balance results, as measured by the Balance Error Scoring System (BESS). The present study aimed to determine whether a new low-cost force plate for concussion balance assessment, the Balance Tracking System (BTrackS), is subject to similar fatigue effects. Significant fatigue effects were only evident immediately following a fatigue protocol (p &gt; .05), and were fully resolved within 5 min postfatigue. These results suggest that the BTrackS Balance Test (BBT) is more fatigue resistant than the BESS, and support use of the BBT as a potentially more reliable alternative to the BESS during immediate sideline balance testing.

Continued alarm sound was not associated with expression of eeg markers of mental fatigue.

Mental fatigue is one of the main factors which leads to performance errors. Previous studies indicated that mental fatigue can be detected using EEG. Here, we attempted to see if comparable EEG changes can be observed after an exposure to a continuing alarm sound.Eleven university students (7 males, 4 females), with ages ranging between 18•25 years, participated as volunteer subjects. The participants had no medical, psychiatric, or head injury records, or any known problems with their hearing. The subjects remained seated during the session with their eyes closed. The EEG was recorded by using an iWorx EEG System with five reusable gold cap electrodes 4mm in diameter placed on the subject’s forehead, over the right and left temporal lobes, and on the right and left parietal-occipital areas. A standard alarm sound with waves of high frequency (up to 6500Hz) was introduced to the subject for 70 seconds through noise cancelling headphones, using sound volume at or below 75 db. The frequencies and amplitudes of the alpha and beta waves were calculated using LabScribe3 software packages. After the movement artifacts and failures of electrode placement were dissected, the effect of fatigue on EEG markers was analyzed in 10 second increments, using 1- way ANOVA. The preliminary finding demonstrated great individual variability between the subjects, but did not reveal a significant effect of fatigue on the EEG markers. We postulated that fatigue has more prominent influences on theta waves which were not measured in this study. Applications of the findings are discussed.

Postural stability with exhaustive repetitive sit-to-stand exercise in young adults

Previous research has indicated that muscle fatigue due to repeated bouts of physical activity can have negative residual effects on balance; however investigations using multi-joint forms of exercise involved in everyday settings and determination of how control of posture is altered during the physical activity itself are limited. The purpose of this investigation was to evaluate alterations in postural stability before, during, and after prolonged multi-joint STS exercise in healthy young adults. Center of pressure (COP) acquisitions were collected during repetitive STS exercise, while voluntary limits of stability (LOS) testing was performed before, immediately after, and 10min after STS exercise. By 50% total STS exercise time, fatigue resulted in increased anterio-posterior (y) and medio-lateral (x) COP path lengths (p=0.003 and p=0.018 respectively) and an anterior shift of COP at seat-off towards the mid-foot (p=0.010). No significant change in LOS mean amplitude was found after STS exercise; however a significant fatigue effect resulted in increased COPy sway velocity at maximal lean positions (p=0.006), but returned to PRE values after 10min of rest. Declines in postural stability during repetitive STS exercise was associated with reduced control of COP, as well as a reduced ability to stably control COP at extreme postural limits; however, 10min was adequate in young adults for recovery. These results may have important implications for monitoring fall risk due to acute bouts of exercise induced muscle fatigue from repetitive multi-joint activities such as the STS.

IDENTIFICATION OF DAMAGED ZONES IN C/PPS SPECIMENS SUBJECTED TO FATIGUE LOADING BASED ON HIGH-RESOLUTION THERMOGRAPHY

In this study high resolution thermography is used for identification of damaged zones in Carbon fiber/polyphenylene sulfide (C/PPS) long fiber composite specimens with induced impact damage subjected to tensile fatigue loading. Image processing techniques were applied on thermographs from all loading cases to obtain segmented images of the damaged location that were then used for calculation of the heated area. Results show that the considered method can be used to identify heated area in the vicinity of damage with high confidence at low number of cycles where no significant fatigue effect is present in the material.

Long-Term Muscle Fatigue After Standing Work.

The aims of this study were to determine long-term fatigue effects in the lower limbs associated with standing work and to estimate possible age and gender influences. The progressive accumulation of muscle fatigue effects is assumed to lead to musculoskeletal disorders, as fatigue generated by sustained low-level exertions exhibits long-lasting effects. However, these effects have received little attention in the lower limbs. Fourteen men and 12 women from two different age groups simulated standing work for 5 hr including 5-min seated rest breaks and a 30-min lunch. The younger group was also tested in a control day. Muscle fatigue was quantified by electrically induced muscle twitches (muscle twitch force [MTF]), postural stability, and subjective evaluation of discomfort. MTF showed a significant fatigue effect after standing work that persisted beyond 30 min after the end of the workday. MTF was not affected on the control day. The center of pressure displacement speed increased significantly over time after standing work but was also affected on the control day. Subjective evaluations of discomfort indicated a significant increase in perception of fatigue immediately after the end of standing work; however, this perception did not persist 30 min after. Age and gender did not influence fatigue. Objective measures show the long-term effects of muscle fatigue after 5 hr of standing work; however, this fatigue is no longer perceived after 30 min of rest postwork. The present results suggest that occupational activities requiring prolonged standing are likely to contribute to lower-extremity and/or back disorders.

청각자극을 이용한 무안경방식 3D 영상의 휴먼팩터 평가

본 연구는 다차원 영상 시각피로를 정량적으로 평가하기 위해 선택적 주의이론에 근거한 청각자극 실험패러다임을 이용하여 시청 전후의 태스크 퍼포먼스 변화를 비교 평가하고자 하였다. 21명의 대학생들이 약 80분의 모바일 3D 콘텐츠 시청 전후에 청각자극을 이용한 선택적 주의 태스크를 각각 수행하였다. 실험참가자들의 주관피로평가 결과를 본페로니의 알파 수정을 적용한 윌콕슨 부호 순위 검정으로 분석하고 피로군과 비피로군으로 분류하여 태스크 퍼포먼스를 비교 평가하였다. 비피로군의 경우 시청 전후 태스크 퍼포먼스 인덱스에서 유의미한 차이가 나타나지 않았으나, 피로군의 경우 모바일 3D 콘텐츠 시청 후에 타겟에 대한 반응 시간이 유의하게 증가하고 반응 정확도가 유의하게 감소하였다. 작업기억 태스크 정확도의 경우는 두 그룹 다 유의미한 차이를 보이지 않았다. This study investigated changes in behavioral performance before and after watching a multi-view 3D content by using auditory stimuli based on the selective attention theory in order to quantitatively evaluate 3D visual fatigue. Twenty-one undergraduates were asked to report on their current visual and physical condition both in the pre- and post-experiment. A selective attention task was conducted before and after mobile 3D viewing to compare the changes in performance. After performing a Wilcoxon's matched-pairs signed-ranks test on the subjective ratings of 3D visual fatigue, participants were categorized into two groups, unfatigued and fatigued group with a definite criterion. For the unfatigued group, no significant fatigue effects were found in behavioral response times and accuracies to specific auditory targets. In sharply contrast to the unfatigued group, the fatigued group showed significantly delayed response times and less response accuracies. However, no significant changes in accuracies for a working memory task were observed in both groups.

Trunk muscle fatigue and its implications in EMG-assisted biomechanical modeling

Muscle fatigue affects the underlying EMG-force relationship on which EMG-assisted biomechanical models rely. The aim of this study was to evaluate the impact of short duration muscle fatigue on the muscle gain value. Participants performed controlled, isometric trunk extension exertions at 10, 20, and 30 degrees of trunk flexion and controlled isokinetic trunk extension exertions at 5 and 15°/sec on five separate days. Fatigue of the lumbar extensors was generated by moderate-intensity, trunk extension exertions. Participants performed controlled test contractions at defined intervals throughout the fatiguing bout and the EMG activities of trunk muscles were collected. These EMG data were employed in a standard EMG-assisted model and fatigue-dependent trends in the gain factor were evaluated. The results of this study show a significant effect of fatigue on the gain factor. Further analysis revealed that by reducing the magnitude of the gain factor in proportion to the drop in median frequency of the EMG signal of the fatigued muscle, a more accurate estimate of muscle force can be calculated. Mean normalized error between predicted internal moments and the measured external moments improved from 17.5 to 9.6% error via the implementation of this modified gain factor. Relevance to industryBiomechanical models are used to quantify low back stress during occupational lifting tasks. Understanding how these models need to be modified under conditions of muscular fatigue will provide more accurate estimates of stress and can help reduce the incidence of low back injury.

Visual fatigue effects on vergence dynamics in asymptomatic individuals

To evaluate objectively changes in vergence dynamics following intentional visual fatiguing tasks using congruent (C) and non-congruent (NC) vergence stimulus demands. Pre- and post-task vergence dynamics to a 10.3° disparity stimulus were recorded objectively in 12 adult, asymptomatic individuals for both convergence and divergence. There were two fatigue-inducing tasks: Congruent or C-task: Subjects altered bifixation (50 cycles) between reduced Snellen charts at 2 m and at 20 cm every 3 s. Non-congruent or NC task: Subjects performed 50 cycles of vergence flipper (7Δ BO/BI), while bifixating a reduced Snellen chart at 40 cm. Pre- and post-task mean amplitude, time constant, peak velocity, and steady-state response variability were compared. There was a significant increase in mean post-task, steady-state response variability for both the C and NC tasks. However, there were no significant group differences for either convergence or divergence between the pre- and post-mean amplitude, time constant, and peak velocity parameters for both the C and NC tasks, although post-task peak velocity was consistently reduced. Steady-state vergence response variability was found to be the critical objective parameter to demonstrate significant fatigue effects in the group. Peak velocity was also consistently reduced to a small extent in the NC task. We speculate that these fatigue effects are of a central, and not of peripheral, origin.