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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose was to examine the relation between voluntary muscle activation and neuromuscular endurance of individual subjects based on the pattern of surface electromyography (EMG). The voluntary muscle activation was estimated from the relation between voluntary force and tetanic force superimposed on the voluntary force (twitch interpolation technique). 14 male subjects (10 regular exercisers and 4 sedentary; 21-29 years old) were divided into a High Voluntary Activation group and a Low Voluntary Activation group. A significant positive correlation of .72 (p<.01) was found between maximum voluntary torque and voluntary activation. A fatigue test was conducted during isometric contractions of 60% and 20% maximum voluntary torque. The endurance time was significantly longer for the Low Voluntary Activation group than the High Voluntary Activation group. The mean power frequency of voluntary EMG obtained from the vastus lateralis muscle decreased consistently whereas the average rectified value increased. The final change of mean power frequency relative to the initial value was significantly greater in the 60% Fatigue task than in the 20% Fatigue task. For the 60% Fatigue task, the final change of mean power frequency and average rectified value relative to the initial value was significantly greater in the Low Voluntary Activation group than in the High Voluntary Activation group. These results suggest that the individual differences in voluntary activation determine the neuromuscular performance usually evaluated as maximum voluntary torque and endurance time and that the voluntary activation may depend on the daily exercise.
Percept Mot Skills 2002 Oct
PMID:Effects of voluntary activation on neuromuscular endurance analyzed by surface electromyography. 1243 59

For 36 previously sedentary, asymptomatic women the relation of changes in Fatigue and Energy after exercise and over a 14-wk. period associated with participating in a moderate cardiovascular exercise program was analyzed. Scores on the Exercise-induced Feeling Inventory subscale of Physical Exhaustion significantly decreased, and those on the subscale of Revitalization significantly increased immediately after completion of exercise. Feeling state scores before exercise (high vs low on Physical Exhaustion and Revitalization) were not significantly associated with the change in scores on the subscales. Scores on the Profile of Mood States subscale of Fatigue significantly decreased and on the subscale of Vigor significantly increased over the 14-wk. study. Participants with initially higher Fatigue scores showed significantly greater mean change over the 14 wk. than those with lower scores. No such difference was found for changes in Vigor scores. Significant correlations between both measures of Fatigue (Physical Exhaustion and Fatigue) (r = .36) and Energy (Revitalization and Vigor) (r = .54) were found which indicated a relation between changes in feeling after exercise and those over 14 wk. Limitations and implications of the findings were discussed based on theories of exercise-induced affective change.
Percept Mot Skills 2002 Dec
PMID:Relation of rated fatigue and changes in energy after exercise and over 14 weeks in previously sedentary women exercisers. 1250 65

The sleep EEGs and fatigue of 9 female family caregivers (age M=65 yr.) and 9 female noncaregivers (age M=67 yr.) were measured during two successive nights at their houses. Perceived quality of sleep was measured by the Sleep Evaluation Questionnaire. Fatigue was measured by a self-rated questionnaire, the Perceived Symptoms of Fatigue, and by critical flicker fusion (CFF) frequency. The caregivers had a significantly higher percentage of Stage 1 and a lower percentage of Stage 2 during the 2nd cycle and a higher percentage of Stages 3+4 during the 3rd cycle than those of the noncaregivers. Caregivers had significantly higher percentages of EEG waves of 7-9 Hz in the 1st cycle and 6-9 Hz in the 2nd cycle and significantly lower percentages of 2-3 Hz in the 1st cycle than those of the noncaregivers. The caregivers reported a lower quality of sleep and higher perceived fatigue symptoms and also lower CFF frequency (increased physiological fatigue) than noncaregivers. The caregivers' sleep EEGs were associated with their higher sleep needs and fatigue.
Percept Mot Skills 2002 Dec
PMID:Sleep EEG patterns and fatigue of middle-aged and older female family caregivers providing routine nighttime care for elderly persons at home. 1250 80

Scores on the Profile of Mood States were collected from football players at a small university each week prior to a Saturday football contest. The scores were analyzed to assess whether mood varied as a function of the outcome of the previous week's game. Although the subjects' overall mood state was not influenced by the outcome of the games, scores on Tension, Vigor, Fatigue, and Confusion varied. Fatigue and Confusion were related to the outcomes of the games and gave partial support to the hypothesis that the players' mood would vary according to the outcome of the games played.
Percept Mot Skills 2003 Apr
PMID:Variations in mood state as a function of a football season. 1277 26

Currently, the carbohydrate-restricted diet is very popular. Atkins' book, Dr. Atkins' Diet Revolution, has sold millions in its more than 25 years of existence. His book promotes the carbohydrate-restricted diet, which focuses on the consumption of proteins and fats as primary calorie and energy sources, while severely restricting carbohydrates. However, when carbohydrates are restricted from the diet, the body's primary energy source is reduced considerably. Therefore, the purpose of this study was to compare the psychological responses to exercise of individuals when on a carbohydrate restrictive diet and when on a noncarbohydrate restrictive diet. For this study, 17 participants practiced a noncarbohydrate-restricted diet for three weeks and the carbohydrate-restricted diet for three weeks, while maintaining previous exercise habits. After each exercise session, the participants completed the Physical Activity Affect Scale, which measures Positive Affect, Negative Affect, Tranquility, and Fatigue. Simple one-way analyses of variance indicated significant treatment differences (ps<.05) relative to Negative Affect, Positive Affect, and Fatigue. The results of the study indicate as predicted, that, when a person restricts carbohydrates from the diet, he will experience more fatigue, more negative affect, and less positive affect in response to exercise than those individuals who are not restricting carbohydrates.
Percept Mot Skills 2003 Apr
PMID:Effects of a carbohydrate-restricted diet on affective responses to acute exercise among physically active participants. 1277 43

The purpose of the present study was to investigate the factorial validity of the Brunel Mood Scale, which measures anger, confusion, depression, fatigue, tension, and vigor, for water-skiers. Participants were 345 water-skiers (age range 16 to 39 years, men: n=311, women: n=34) who completed the scale approximately 1 hour before a water-skiing competition. Confirmatory factor analysis indicated support for the validity of the 6-factor model, with a Comparative Fit Index of .90 and Root Mean Squared Error of Approximation of .07. Internal consistency coefficients were above the .70 criterion. It is suggested that the Brunel Mood Scale shows factorial validity for use with water-skiers and that researchers should continue to assess validation of the Brunel Mood Scale with other measures and with specific appropriate samples.
Percept Mot Skills 2003 Oct
PMID:Confirmatory factor analysis of the Brunel Mood Scale for use with water-skiing competition. 1462 Feb 57

In this study, changes in movement coordination caused by fatigue that developed during repetitive lifting were examined. Five men performed 6 times a 5-min bout of lifting an 8-kg barbell at 15 lifts/min, using two lifting techniques; one minimized trunk rotation (squat lift), and the other minimized rotation in the knee joint (stoop lift). Kinematics and dynamics were studied by means of movement analysis and inverse dynamics, using a two-dimensional linked segment model. Within-subject variation over repetitive lifts of the time course of joint angles was smaller than between-subjects variation on the first analyzed lift. Relative timing between joint rotations did not change significantly across repetitive lifts, except between knee and hip in the squat lift. No change of the lumbosacral torque over repetitive lifts was found. The adaptability of the neural control appeared to be sufficient to accommodate the strong changes of the input-output characteristics of the muscles caused by fatigue so that an essentially constant performance of the movement act was maintained.
J Mot Behav 1996 Dec
PMID:Fatigue-related changes in the coordination of lifting and their effect on low back load. 1476 53

The fractionation of a simple right-hand grip total reaction time (RT) into central and peripheral temporal components (premotor and motor time, respectively) helped to define the site of RT change following an auditory induced startle response and two fatiguing hand-grip exercise regiments for eight males and eight females. Following the startle response, mean values for RT significantly lengthened, due primarily to an increase in premotor time. In contrast, lengthened RT following both fatigue regimens (42% and 55% strength decrements) were due to substantial increases in the motor time component. These results suggest that although performance of tasks which demand a high degree of precision, accuracy, and fine motor control may be disrupted by the introduction of such stressors as an induced startle and local muscular fatigue, the neuromuscular mechanisms mediating performance disruption are dissimilar.
J Mot Behav 1977 Dec
PMID:Startle response and muscular fatigue effects upon fractionated hand grip reaction time. 1497 7

A preliminary 10-wk. study was conducted to determine the effect a combined strength and cardiovascular exercise protocol had on both physiological and psychological change in 17 older (M age = 66.8 yr.), formerly sedentary women. The protocol was associated with better adherence than typically found for new and returning exercisers. Significant improvements over 10 wk. were found on Body Mass Index, body fat, resting heart rate, and balance. Significant, positive changes in mean ratings were also found on Physical Self-concept, Total Mood Disturbance, Depression, and Fatigue (small to moderate treatment effect sizes). Although no significant changes were found for rated Tension, Vigor, Anger, and Confusion, mean changes were in the desired direction and rated Tension showed a moderate effect size. The need for replication, including a control group and follow-up, plus continued research on exercise protocols both well-tolerated and effective for older individuals and other specific groups, were discussed.
Percept Mot Skills 2004 Feb
PMID:Preliminary evaluation of a 10-wk. resistance and cardiovascular exercise protocol on physiological and psychological measures for a sample of older women. 1505 79

Subjects are able to judge the strength of muscle contraction. In theory, the force of muscular exertion could be perceived either from mechanoreceptor afferents or from knowledge of central motor command (corollary discharge). Sensations of great effort or exerted force have been described by subjects when their limbs were weakened by fatigue or partial paralysis. This has been taken as evidence that effort sensations arise from central motor commands rather than from mechanoreceptor afferent signals produced by muscle contraction. To differentiate between these possibilities, we used neuromuscular block to completely paralyze four waking subjects and required them to attempt maximal contraction of inspiratory muscles and of hand muscles. They were questioned after recovery about what their sensations were when attempting these contractions. None described the sensations of exerted force, great effort, or heaviness, which would have been expected if motor commands alone were the source of these sensations. The contradiction between our findings and those previously reported suggests that the specific neural mechanisms for effort sensations must be reexamined.
J Mot Behav 1993 Dec
PMID:What do fully paralyzed awake humans feel when they attempt to move? 1506 97


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