muscle fatigue

Repeated, intense use of muscles leads to a decline in performance known as muscle fatigue. Many muscle properties change during fatigue including the action potential, extracellular and intracellular ions, and many intracellular ..

Intracellular acidification of skeletal muscles is commonly thought to contribute to muscle fatigue. However, intracellular acidosis also acts to preserve muscle excitability when muscles become depolarized, which occurs with working ..

..accumulation of lactic acid, or in reality lactate and/or hydrogen (H+) ions, is a major cause of skeletal muscle fatigue, i.e. decline of muscle force or power output leading to impaired exercise performance...

..Progressive muscle weakness and atrophy in mdx mouse muscle is associated with a decline in regenerative potential and changes in activation of the mTOR signaling pathway...

..that supports glutathione synthesis, has been shown to lessen oxidation of cellular constituents and delay muscle fatigue. In humans, NAC pretreatment improves performance of limb and respiratory muscles during fatigue protocols and ..

..In conclusion, rTO(2) in DYN and IST were similar in spite of major differences in the MMG and EMG responses of the muscle during contraction periods. This may relate to the surprisingly lower IMP in DYN than IST...

..The fatigue-induced changes recovered rapidly. We conclude that CHF soleus fibers fatigue more rapidly than Sham fibers because of a reversible fatigue-induced decrease in myofibrillar function...

There are some indications that low-level laser therapy (LLLT) may delay the development of skeletal muscle fatigue during high-intensity exercise...

..We conclude that pre-exercise irradiation with a laser dose of 1.0 J and 904 nm wavelength significantly delays muscle fatigue and decreases post-exercise blood lactate and CK in this rat model.

..05) with a decreased ratio of torques generated at 20:50 Hz, indicating an involvement in low frequency fatigue; however, no correlations between the muscle relaxation times or rates of change of torque and calcium uptake were observed...

..was to investigate the responses of the spine during sudden loading in the presence of back and abdominal muscle fatigue, with a primary focus on the implications for spinal stability...

..Knowledge of the mechanism of free-radical formation in exercise is important because it will be useful to prevent oxidative stress and damage associated with exhaustive physical activity...

..CrS presented a protective effect on muscle injury induced by strenuous contractile activities...

..5 J/cm2 LLLT group and the control group. We conclude that LLLT doses of 0.5 and 1.0 J/cm2 can prevent development of muscular fatigue in rats during repeated tetanic contractions...

..proposed as an alternative method for the frequency analysis of surface electromyography (EMG) in the study of muscle fatigue during sustained, isometric muscle contractions...

..These findings show that the t-system chloride conductance plays a vital role during normal activity by countering the effects of K(+) accumulation in the t-system and maintaining muscle excitability...

To investigate if development of skeletal muscle fatigue during repeated voluntary biceps contractions could be attenuated by low-level laser therapy (LLLT).

..92) and the heavy on-transient (r = 0.71). These data demonstrate, for the first time in humans, that an increase in muscle [PCr] results in a slowing of [PCr] dynamics in exercise and subsequent recovery...

..We have now employed this difference to study mechanisms of skeletal muscle fatigue. Isolated whole soleus and extensor digitorum longus (EDL) muscles were fatigued by repeated tetanic ..

..This phenomenon possibly involves attenuation of the depolarization caused by stimulation- or exercise-induced run-down of the transsarcolemmal K(+) gradient...

..from exercising locomotor muscles results in an overshoot in CMD and power output normally chosen by the athlete, thereby causing a greater rate of accumulation of muscle metabolites and excessive development of peripheral muscle fatigue.

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..the effect of ankle muscle vibration on the regulation of postural sway in bipedal stance following ankle muscle fatigue. Center of foot pressure displacements were recorded using a force platform...

..From a clinical point of view, muscle fatigue profiles are different between healthy children and children with muscle and metabolic diseases...

..These findings indicate that genetic CLC-1 deficiency not only affects muscle relaxation (myotonia) but also modulates diaphragm performance during the contractile phase of the contraction-relaxation cycle...

The mechanisms responsible for the inhibition of shortening velocity that occurs during muscle fatigue have not been completely elucidated...

..Background Data: Many other studies in the past demonstrated that LIL had a cytoprotective effect, and a recent study also found that LIL could reduce muscular fatigue during tetanic contractions in rats...

..In vitro, reactive oxygen species reduce myofibrillar Ca2+ sensitivity; however, the importance of this mechanism during in vivo exercise is unknown...

..Changing arterial oxygen content (C(aO(2))) has a highly sensitive influence on the rate of peripheral locomotor muscle fatigue development...

..5 km/day). Despite this, running increased the force output of the plantaris muscle (approximately 50%). Taken together, the results showed that exercise can have beneficial effects on dystrophic skeletal muscles...

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..in humans, quadrupeds, and isolated muscle preparations indicate that antioxidant pretreatment can delay muscle fatigue. In humans, this phenomenon is best defined for N-acetylcysteine (NAC), a reduced thiol donor that supports ..

..To investigate the effects of aerobic and strength exercise on motor fatigue of knee flexor and extensor muscles in subjects with multiple sclerosis (MS)...

..These changes in the contractile properties of fast-twitch skeletal muscle from alpha-actinin-3-deficient individuals would be detrimental to optimal sprint and power performance, but beneficial for endurance performance...

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Historically, an increase in intracellular H(+) (decrease in cell pH) was thought to contribute to muscle fatigue by direct inhibition of the cross-bridge leading to a reduction in velocity and force...

b>Muscle fatigue is an exercise-induced reduction in maximal voluntary muscle force...

The mechanisms of muscle fatigue were studied in small muscle bundles and single fibres isolated from the flexor digitorum brevis of the mouse...

..Aging increases: (1) fatigue within the central nervous system immediately after a low-force fatiguing contraction, and (2) the potential for large neural adaptations during neuromuscular rehabilitation in old adults...

..We hypothesize that during high-intensity exercise a rundown of the transsarcolemmal K(+) gradient is the dominant cellular process around which interactions with other ions and metabolites occur, thereby contributing to fatigue...

..skeletal muscle resulted in abnormality of the triad junction structure, and also increased susceptibility to muscle fatigue. To elucidate the basis of these effects, we investigated the properties of Ca2+-uptake and -release in toxin-..

..acidosis due mainly to lactic acid accumulation has been regarded as the most important cause of skeletal muscle fatigue. Recent studies on mammalian muscle, however, show little direct effect of acidosis on muscle function at ..

..To quantify changes in balance parameters and ranges of postural control at the ankle after isokinetic fatigue...

..after heavy external force perturbation applied to the trunk in the sagittal plane before and after back muscle fatigue, in expected and unexpected conditions...

..MVC relationships at fatigue seems to be related to the impossibility of recruiting fast, but more fatigable MUs, and to the lowering of the global MUs firing during the short isometric force ramp investigated...

..The variations in stimulation frequency, pulse pattern, and pulse number used in this study therefore had little influence on thenar muscle fatigue in control subjects or in spinal cord-injured subjects with chronic paralysis.

..These data indicate that postural fatigue induced by a low-level isometric contraction has no effect on voluntary movement and requires no dramatic adaptation in postural control...

..Therefore, MMG amplitude may be clinically useful for detecting abnormal force contributions of individual muscles during dynamic contractions, and determining whether various treatments are successful at correcting such abnormalities...

..It needs more detailed control for muscular activity...

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..nuclear magnetic response spectroscopy (31P-NMRS) detected muscle energy metabolism during plantar flexion and muscle fatigue evaluated by 1-s electrical stimulation at low (10 Hz) and high (50 Hz) frequency...

..Thus during sustained evoked contractions with stimulation frequencies within the physiological range, frequencies can vary significantly without changing the overall force-time integral...

..It can also be concluded that the recovery of twitch contractile properties does not necessarily follow that of maximal muscle strength...

To investigate the effects of muscle fatigue on force sense at the ankle joint, 10 young healthy adults were asked to perform an isometric contra-lateral force ankle-matching task in two experimental conditions of: (1) no-fatigue and (2) ..

..005) in the two muscle groups. This dissociation between the mechanical and myoelectrical manifestation of muscle fatigue in ALS indicates that a reduction in muscle fiber conduction velocity (MFCV) may be a contributing peripheral ..

Whereas the acuity of the position sense at the ankle can be disturbed by muscle fatigue, it recently also has been shown to be improved, under normal ankle neuromuscular state, through the use of an artificial tongue-placed tactile ..

..46-0.82, P = 0.001-0.03). We conclude that ENS and MNS provide similar quadriceps muscle function assessment, while Fpaired(10:100) is a better index than T2(10:100) of low- to high-frequency fatigue of the quadriceps in vivo...

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..the influence of massage on the skin and the intramuscular circulatory changes associated with localized muscle fatigue. MATERIAL/METHODS: Twenty-nine healthy male subjects participated in two experimental sessions (massage and ..

..b>Muscle fatigue was generated using a dead-lift exercise performed to exhaustion...

..3+/-4.4 degrees. These changes were accompanied by a lateral shift of the body's center of mass towards the non-reaching arm. These findings suggest a compensatory strategy to decrease the load on the fatigued shoulder musculature...

..This study aimed to evaluate the benefit of using low-intensity running or electromyostimulation (EMS) to hasten the recovery process from eccentric-contraction-induced injury...

..Central fatigue is the inability of central commands to recruit maximum evocable muscle force during voluntary contraction. Here, we investigate how fatigue affects the inhibitory circuits of the motor cortex...

..To examine the effectiveness of four interventions on the rate and magnitude of muscle damage recovery, as measured by creatine kinase (CK)...

..Shoulder muscle fatigue has been associated with alterations in joint mechanics and possibly contributes to shoulder dysfunction...

The purpose of this study was to determine the effects of shoulder muscle fatigue on three dimensional scapulothoracic and glenohumeral kinematics. Twenty healthy subjects participated in this study...

..This is in contrast to the marked effects of ADP on force responses in fast-twitch muscle fibres and may contribute to the fatigue-resistant nature of slow-twitch muscle fibres...

..Frailty is increasingly recognized as a geriatric syndrome that shares common biomedical determinants with rapid muscle fatigue: aging, disease, inflammation, physical inactivity, malnutrition, hormone deficiencies, subjective fatigue, ..

..contractions; the aim was to characterize the effect of shortening and of temperature on the initial phase of muscle fatigue. Short tetanic contractions were elicited at a control repetition rate of 1/60 s, and fatigue was induced by ..

..From these studies, we conclude that L-CAR delays muscle fatigue by the reducing free radical-induced oxidative damage of IH exposure.

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..Altogether, the present findings suggested that the AFO allowed the subjects to limit the postural perturbation induced by a localized fatigue of the ankle muscles during bipedal quiet standing...

..Postural control was substantially affected both by the additional body weight, and by muscle fatigue in the triceps surae muscles...

Although previous studies have investigated the effects of bilateral muscle fatigue on bipedal postural control, whether and how the central nervous system could adapt to unilateral muscle fatigue for controlling bipedal stance remains to ..

..are used repeatedly and intensively and a variety of intracellular mechanisms appear to contribute to this muscle fatigue. Intracellular calcium release declines during fatigue and has been shown to contribute to the reduction in ..

..min) VDT work at four different screen heights on head-neck posture, muscle activity and the development of muscle fatigue. The results show that lowering screen height, starting from 15 cm above the baseline (i.e...

..We therefore suggest that the physiological effects of the K(ATP) channel are enhanced after denervation...

b>Muscle fatigue has been shown to result in early onset of anticipatory postural adjustments (APAs) relative to those produced in a non-fatigued state...

The effect of an amino acid mixture on the recovery from muscle fatigue after eccentric exercise (ECEX) training was examined in twenty-two male college students. The administration of 5...

..b>Muscle fatigue was determined after 20, 30, 40 and 50 repetitions by the fatigue index, the percent decrease in performance ..

..To better understand fatigue-related changes in shortening velocity in different muscles, we compared the fatigue response of two muscles in humans with different physiological properties using the same criterion for task failure...

The purpose of this study was to evaluate test-retest reliability of two different measures of isokinetic quadriceps muscle fatigue.

..Neural drive reduction may have contributed to the relative preservation of peripheral function and also affected the evolution of the running speed during the 24TR...

..We asked whether ERL elicits inspiratory as well as expiratory muscle fatigue. On four separate days, seven male subjects underwent ERL to task failure...

Skeletal muscle fatigue is most often studied in vitro at room temperature and is classically defined as a decline in maximum force production or power output, exclusively linked to repeated isometric contractions...

..The aim of this study was to investigate changes in muscle function, muscle structure, and calpain activity after high-force eccentric exercise...

..We conclude that low levels of clenbuterol reduce muscle fatigue in slow muscles during disuse and this beta-agonist may also have therapeutic value for reducing fatigue in ..

The role of mitochondrial K(ATP) (mitoK(ATP)) channels on muscle fatigue was assessed in adult mouse skeletal muscle bundles. Muscle fatigue was produced by eliciting short repetitive tetani...

b>Muscle fatigue and dual-task walking (e.g., concurrent performance of a cognitive interference (CI) while walking) represent major fall risk factors in young and older adults...

..Thus, slow-twitch muscle is severely affected in CHF by slower than normal relaxation and significantly reduced fatigue resistance, which may explain the sensation of both muscle stiffness and fatigue in CHF patients...

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..The spinal mechanisms exposed here may contribute to the development of central fatigue in human muscles...

..We examined the effect of 4 (WK4) and 8 wk (WK8) of neuromuscular electrical stimulation (NMES) training on both endurance time and mechanisms contributing to task failure...

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..This study thus provides further insight into the factors contributing to residual fatigue in GBS patients...

The present study investigated how muscle fatigue influences single degree-of-freedom elbow flexion movements and their associated patterns of phasic muscle activation...

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..05) greater before and after decrements following exercise for the biceps brachii and brachioradialis. Greater exercise efficiency with less motor unit recruitment and fatigue results from eccentric exercise...

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..Signals also decay during fatigue -their decay actually causing fatigue-- and in old age. In muscle fatigue, the stores are depleted...

..Moreover, oral NAC has been found to improve muscle fatigue (5-7) which is reported to be the most disabling symptom in 53% of patients with SLE (8)...

..Due to the potential of collapse (from muscle fatigue) and the need to guide uncontrolled degrees of freedom, hybrid systems appear to offer the greatest promise ..

..ES is delivered at a relatively high frequency between 20 and 35 Hz, which can lead to more rapid onset of muscle fatigue.7 Third, due to stimulation-induced pain and muscle fatigue, an escalating stimulation schedule is needed...

..ES is delivered at a relatively high frequency between 20 and 35 Hz, which can lead to more rapid onset of muscle fatigue.7 Third, due to stimulation-induced pain and muscle fatigue, an escalating stimulation schedule is needed...

The overall goal is to determine the magnitude and mechanisms of age-related changes in muscle fatigue (decrease in maximal force-generating capacity, MVC)...

..that is important for the achieving maximal metabolic efficiency, which when inactivated causes extreme muscle fatigue. We found major reductions of Slc25a25 gene expression in skeletal muscle biopsies from obese and type 2 ..

..Identical AAS treatment of male rats had no effect on DIA muscle fatigue using the same stimulation paradigm...

..Pathologies of breathing such as sleep apnea, central alveolar hyperventilation, central inspiratory muscle fatigue and (perhaps) sudden infant death syndrome result from failure to generate adequate respiratory muscle ..

..Signals also decay during fatigue -their decay actually causing fatigue-- and in old age. In muscle fatigue, the stores are depleted...

..A distinct phenotype of mg29(-/-) mice is their increased susceptibility to muscle fatigue, which may be linked to an altered Ca signaling in the mutant muscle...

..functional strength of the inspiratory muscles which places them at risk for the development of respiratory muscle fatigue and ventilatory failure and contributes to sensations of dyspnea and ultimately to a decrease in functional ..

..Physiologically, the inhibition of CLC-1's common-gating by ATP is critical for overcoming muscle fatigue. The slow/common-gating mechanism is also pathologically important because mutations that disrupt the common- ..

..Physiologically, the inhibition of CLC-1's common-gating by ATP is critical for overcoming muscle fatigue. The slow/common-gating mechanism is also pathologically important because mutations that disrupt the common- ..

..b>Muscle fatigue is a major problem in the peripheral neuromuscular stimulation...

..involvement in various fatigue syndromes: first, is the intensity of the BOLD response in motor cortical areas quantitatively dependent on force development, and second, how is this central response altered by peripheral muscle fatigue?

..joints and an orthosis that can be controlled and can provide anti-gravity support to reduce stimulated muscle fatigue. Because the ESO approach is new, technical feasibility must be demonstrated before undertaking a ..

..Respiratory insufficiency is the usual cause of death in many primary neuromuscular disorders. Respiratory muscle fatigue is believed to be a major factor in hypercarbic respiratory failure associated with lung and/or cardiovascular ..