Disease relevance of Muscle Fatigue

• Hyperoxia and moderate hypoxia fail to affect inspiratory muscle fatigue in humans [1].
• If muscle did not produce lactate, acidosis and muscle fatigue would occur more quickly and exercise performance would be severely impaired [2].
• CASE: A 21-year-old primigravida with cytochrome C oxidase-deficient mitochondrial myopathy who presented for obstetric care at 8 weeks' gestation complained of muscle fatigue and spasm after exertion [3].
• This review will focus on these findings and will highlight the pyruvate dehydrogenase complex as a novel therapeutic target towards the treatment of peripheral vascular disease, or any other disease state where premature muscular fatigue is prevalent due to metabolite accumulation [4].
• OBJECTIVE: To measure maximal voluntary strength and central activation without fatigue, and to assess both peripheral and central components of muscle fatigue of the elbow flexor muscles, during exercise, in a group of patients with fibromyalgia (FM) (n = 11) [5].

Psychiatry related information on Muscle Fatigue

• Habitual level of physical activity and muscle fatigue of the elbow flexor muscles in older men [6].

High impact information on Muscle Fatigue

• N-acetylcysteine inhibits muscle fatigue in humans [7].
• The highly significant linear relationship between increases of H+ and H2PO4- and the decline of MVC strongly suggests that both H+ and H2PO4- are important determinants of human muscle fatigue [8].
• The goal of these experiments was to investigate the relationship of ATP, phosphocreatine (PCr), inorganic phosphate (Pi), monobasic phosphate (H2PO4-), and pH to human muscle fatigue [8].
• We have identified a 38-year-old man who has a lifelong condition of fishlike body odor and chronic muscle fatigue, accompanied by elevated levels of the muscle form of creatine kinase in serum [9].
• We conducted a prospective trial to evaluate a global muscle fatigue parameter--the blood lactate level achieved at maximal exercise--as a method of distinguishing between diseased and nondiseased coronary status [10].

Chemical compound and disease context of Muscle Fatigue

• We report a patient with myasthenia gravis (MG) who had marked clinical benefit in response to treatment with mycophenolate mofetil as documented by serial quantitative measures of strength and muscle fatigue [11].
• At the highest dose, muscle fatigue, lactic acidosis and an over-utilization of phosphocreatine was observed in the gastrocnemius muscle during mild stimulation of 1 Hz frequency [12].
• Contradictory reports have suggested that serum free carnitine and acylcarnitine concentrations are decreased in patients with chronic fatigue syndrome (CFS) and that this is a cause of the muscle fatigue observed in these patients [13].
• Hyperinsulinaemia is associated with impaired peripheral muscle glucose uptake and metabolism, and might contribute to muscular fatigue on exertion in patients with previous myocardial infarction or heart failure [14].
• Oral L-carnitine has been reported to lower the elevated serum myoglobin of renal failure in chronic peritoneal dialysis patients, and intravenous L-carnitine can improve muscle fatigue and cramps in chronic hemodialysis patients [15].

Biological context of Muscle Fatigue

• These data indicate that NAC supports glutathione homeostasis in exercising humans and may delay muscle fatigue during repetitive handgrip exercise [16].
• Several investigators indicate that theophylline has an inotropic effect on respiratory muscle, causing enhanced muscular contraction and prevention of muscle fatigue [17].
• Levocarnitine administration in elderly subjects with rapid muscle fatigue: effect on body composition, lipid profile and fatigue [18].
• An explanation for these minimal biochemical alterations at exhaustion is unclear, but could relate to exercise being limited well below estimated maximum cardiac output and muscle O2 extraction levels by early, unexplained muscle fatigue [19].
• 4. Streptozotocin-induced diabetes has no effect on sternohyoid muscle fatigue or the tension-frequency relationship, but does reduce contractile kinetics and increases force generation [20].

Anatomical context of Muscle Fatigue

• Neuromuscular junction disassembly and muscle fatigue in mice lacking neurotrophin-4 [21].
• This reduction in [Ca(2+)](SR) will contribute to the failure of Ca(2+) delivery to the myofilaments which is an important cause of muscle fatigue [22].
• It is unclear whether accumulation of lactate in skeletal muscle fibers during intense activity contributes to muscle fatigue [23].
• We evaluated the effect of global inspiratory muscle fatigue on ventilation and respiratory muscle control during CO2 rebreathing in normal subjects [24].
• To assess the effects of muscle fatigue in patients with focal occupational upper limb dystonia, we studied the effect of a previous maximum fatiguing voluntary contraction on motor performance in 10 musicians with focal occupational dystonia, in 3 musicians with hand motor impairment due to non-dystonic disorders, and in 5 normal musicians [25].

Associations of Muscle Fatigue with chemical compounds

• Circulating autoimmune antibodies may produce symptoms of muscular fatigue by reacting with acetylcholine receptors or calcium binding channels [26].
• Spin-trappers and vitamin E prolong endurance to muscle fatigue in mice [27].
• The mechanisms of muscle fatigue were studied in small muscle bundles and single fibres isolated from the flexor digitorum brevis of the mouse [28].
• In addition, we examined whether induction of inspiratory muscle fatigue alters CO2 responsiveness [29].
• Lactic acid accumulation is generally believed to be involved in muscle fatigue [30].

Gene context of Muscle Fatigue

• CONCLUSION: The results of this study suggest that COX-2-selective inhibition has a beneficial effect on muscle fatigue resistance in hospitalized elderly patients with acute inflammation of infectious origin [31].
• Our data suggest that systemic ablation of sarcalumenin caused enhanced resistance to muscle fatigue by compensatory changes in Ca2+ regulatory proteins that effect SOCE [32].
• Thus, muscle-derived NT-4 is required for maintenance of postsynaptic AChR regions, normal muscular electrophysiological responses, and resistance to muscle fatigue [21].
• It is proposed that MCT1 expression may be important for blood lactate removal after supramaximal exercise based on the existence of lactate shuttles and, in turn, in favor of a better tolerance to muscle fatigue [33].
• Thus, we conclude that the PD may be a good index of the overload of the respiratory movement and available to predict muscle fatigue in COPD patients [34].

Analytical, diagnostic and therapeutic context of Muscle Fatigue

• Our data suggest that, during spontaneous breathing, COPD patients would probably develop inspiratory muscle fatigue, unless continuous positive airway pressure were applied to reduce WPEEPi [35].
• The purpose of the present study was to verify the hypothesis that glucose infusion could attenuate peripheral muscle fatigue in the anaesthetized rat during prolonged indirect electrical stimulation in situ [36].
• DESIGN: Muscle fatigue in the lower back was assessed in healthy subjects using electromyography (EMG), endurance time and the Borg scale [37].
• Since the same elements of performance in the masticatory muscles are influenced by occlusal factors, they link the development of muscular fatigue, discomfort and pain to the dental occlusion [38].

References