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

The physiological and performance effects of carbohydrate ingestion/supplementation on aerobic endurance exercise have been extensively studied. However, little attention has been given to the effects of carbohydrate ingestion on resistance exercise and training. Recent evidence suggests that resistance exercise can elicit a considerable glycogenolytic effect, which can lead to fatigue and strength loss. The ability of carbohydrate ingestion immediately before and during resistance exercise to enhance performance is unclear at present, however carbohydrate ingestion following resistance exercise has been shown to enhance muscle glycogen resynthesis. This may decrease recovery time following resistance exercise and enable an increase in training volume which may enhance physiological adaptations. Also, carbohydrate ingestion during or immediately after resistance exercise has been shown to increase postexercise insulin and growth hormone levels, which may lead to increased protein synthesis and hypertrophy, although this has not been systematically investigated. Despite the potential benefits of carbohydrate ingestion for performance of resistance exercise and adaptation to resistance training, at present little empirical evidence is available to support this hypothesis.
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PMID:Carbohydrate ingestion/supplementation or resistance exercise and training. 877 Dec 82

Muscle phosphofructokinase deficiency (PFKD) is characterized by exercise intolerance due to the enzymatic block in muscle glycolysis. Glucose infusion increases exertional fatigue in these patients, probably by decreasing the availability of free fatty acids (FFA) and ketones, which play a crucial role in ATP production during exercise in PFKD. This suggests that a lower than normal hepatic glucose production would be appropriate during exercise in PFKD. To investigate glucoregulation in PFKD, we measured glucose turnover and hormonal and metabolic responses to 20 minutes of cycle exercise at near maximal effort in three patients with PFKD and in healthy matched controls studied at the same absolute (A, 15 to 30 Watts) and relative (R, 35 to 80 Watts, matched heart rates) work load as the patients. During exercise, mean glucose production was higher in all patients versus controls (30 +/- 4 versus A: 18 +/- 2 and R: 20 +/- 1 mumol.min-1.kg-1). Mean glucose utilization during exercise was similar in patients and controls working at the same relative work load and higher than in controls at the low work load. Exercise-induced increases in arterialized blood were higher in all patients for glucose, FFA, growth hormone, glucagon, and norepinephrine. Plasma alanine and lactate always decreased during exercise in patients and consistently increased in controls. In conclusion, an enhanced neuroendocrine response and a paradoxically exaggerated mobilization of glucose occurs during exercise in PFKD. The responses are probably initiated by neural feedback elicited by disturbances in local muscle metabolism. The responses promote delivery of oxidizable fat to muscle, but at the expense of accumulation and futile cycling of glucose.
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PMID:Paradoxically enhanced glucose production during exercise in humans with blocked glycolysis caused by muscle phosphofructokinase deficiency. 879 77

Hormonal and metabolic responses to electrically induced dynamic exercise were investigated in eight healthy young men with afferent neural influence from the legs blocked by epidural anesthesia (25 ml of 2% lidocaine) at L3-L4. This caused cutaneous sensory anesthesia below T8-T9 and complete paralysis of the legs. Cycling increased oxygen uptake to 1.90 +/- 0.13 (SE) l/min, and fatigue developed after 22.7 +/- 2.7 min. Compared with voluntary exercise at the same oxygen uptake and heart rate, concentrations of blood and muscle lactate (musculus vastus lateralis) as well as plasma potassium increased more while muscle glycogen decreased more during electrically induced exercise. Hepatic glucose production always rose during exercise. However, during involuntary exercise with sensory blockade, it did not match the rise in peripheral glucose uptake and plasma glucose decreased (P < 0.05). Plasma glycerol increased less in electrically induced vs. voluntary exercise, and free fatty acids and beta-hydroxybutyrate decreased only during electrically induced exercise. Epinephrine, growth hormone, adrenocorticotropic hormone, and cortisol levels were higher during involuntary vs. voluntary exercise (P < 0.05). In conclusion, neural and humoral mechanisms exert redundant control with regard to responses of catecholamines and pituitary hormones (growth hormone and adrenocorticotropic hormone). In contrast, neural input from motor centers and feedback from working muscle are important for glucose production and lipolysis during exercise in humans. Humoral feedback is apparently not sufficient to trigger normal mobilization of extramuscular fuel stores.
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PMID:Hormonal and metabolic responses to electrically induced cycling during epidural anesthesia in humans. 880 25

In order to establish whether reported psychological complaints in hypopituitary adults are related to growth hormone (GH) deficiency or other pituitary hormone deficiencies, emotional well-being and cognitive performance were evaluated in 31 men with multiple pituitary hormone deficiencies (MPHD) and in 17 men with isolated growth hormone deficiency (IGHD). Assessments included evaluation of somatic and psychological complaints, depression, fatigue, vigor, tension, state and trait anxiety, iconic memory, short-term memory, long-term memory and perceptual-motor skill. The control group consisted of 41 healthy men, matched for age. Growth hormone secretion was more severely impaired in MPHD than in IGHD patients. Despite oral replacement therapy, MPHD patients also had lower serum testosterone levels than IGHD subjects. The MPHD patients were found to have lower vigor scores, higher state anxiety scores, worse perceptual-motor skill and worse memory performance than controls. In contrast, IGHD patients only showed subnormal memory performance. It was concluded, therefore, that the cognitive impairment in both MPHD and IGHD was related to GH deficiency. The subnormal vigor scores in MPHD patients were attributed to the reduced testosterone levels. The worse perceptual-motor skill in MPHD patients might be related specifically to ACTH deficiency. Finally, the higher state anxiety in MPHD was attributed to a low self-esteem, which may be the psychological consequence of the hypogonadal appearance these patients have. We conclude that, from a psychological point of view, MPHD and IGHD adult patients are quite distinct groups.
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PMID:Cognitive impairments and mood disturbances in growth hormone deficient men. 881 29

Early intervention and attention to nutritional status are essential in patients with cachexia. Identification of reversible causes of decreased energy intake and/or weight loss is the first step in treatment. When such factors cannot be identified, pharmacologic interventions should be considered. To date, megestrol acetate is the most effective appetite stimulant. Appetite and weight gain occur to a greater and more rapid degree as megestrol dose increases. Unfortunately, the weight gain is due predominantly to an increase in fat mass. Whether this is due to a lack of exercise in the face of increased caloric intake and/or to the hypogonadal effects of megestrol acetate is being tested in ongoing clinical trials. Anabolic agents, particularly growth hormone, are exciting potential therapies. No data are yet available on alternate doses and schedules of growth hormone or on its effect in patients with decreased oral intake. Current studies addressing combination therapy with anabolic agents and appetite stimulants should clarify their respective therapeutic roles.
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PMID:Anorexia/cachexia in patients with HIV: lessons for the oncologist. 883 21

Fibromyalgia (FM) falls into the spectrum of what might be termed 'stress-associated syndromes' by virtue of frequent onset after acute or chronic stressors and apparent exacerbation of symptoms during periods of physical or emotional stress. Patients with FM exhibit disturbances of the major stress-response systems, the HPA axis and the sympathetic nervous system. Integrated basal cortisol levels measured by 24-hour urine-free cortisol are low. FM patients display a unique pattern of HPA axis perturbation characterized by exaggerated ACTH response to exogenous CRH or to endogenous activators of CRH such as insulin-induced hypoglycaemia. The cortisol response to increased ACTH in these stress paradigms is blunted, as is the the cortisol response to exercise. Functional analysis suggests that FM patients may also exhibit disturbed autonomic system activity. For example, plasma NPY, a peptide co-localized with norepinephrine in the sympathetic nervous system, is low in patients with FM. Abnormalities of related neuronal systems, particularly decreased serotonergic activity, may contribute to the observed neuroendocrine perturbations in FM. Finally, other neuroendocrine systems, including the growth hormone axis, are also abnormal in FM patients. Many clinical features of FM and related disorders, such as widespread pain and fatigue, could be related to the observed neuroendocrine perturbations. This hypothesis is supported by the observation that many useful treatments for FM affect the function of these central nervous system centres. Further clarification of the role of neuroendocrine abnormalities in patients with FM, and the relationship of these disturbances with particular symptoms, may lead to improved therapeutic strategies.
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PMID:Neurohormonal perturbations in fibromyalgia. 891 54

We studied the effect of 3 weeks treatment with the selective serotonin reuptake inhibitor (SSRI), fluvoxamine, on hormonal and psychological responses to buspirone, a 5-HT1A receptor partial agonist which also binds to dopamine receptors, in normal male volunteers. Eleven subjects received buspirone, 30 mg, and placebo before, and in week 3 of fluvoxamine treatment (mean dose 127 mg/day). Placebo and buspirone were given in a balanced order, double-blind. Buspirone significantly elevated plasma prolactin (PRL) and growth hormone (GH) concentrations but had no significant effect on cortisol (CORT) or temperature. Significant psychological effects of lightheadedness, tiredness and difficulty thinking occurred. Fluvoxamine treatment resulted in a nearly 3-fold increase in plasma buspirone with a similar enhancement of the PRL response. In contrast the GH and psychological responses were blunted. The increased buspirone concentrations are likely to be due to inhibition of first pass liver metabolism by fluvoxamine acting on the cytochrome P-450 system. The PRL response is probably mediated by antagonism of pituitary dopamine-D2 receptors and its enhancement by fluvoxamine treatment may be a pharmacokinetic effect. The blunting of GH and psychological responses suggest that 5-HT1A receptor function is reduced by chronic fluvoxamine treatment.
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PMID:The effect of chronic fluvoxamine on hormonal and psychological responses to buspirone in normal volunteers. 894 9

Octreotide is a somatostatin analogue: a long-acting release (LAR) formulation of octreotide is designed for once-monthly intramuscular administration. As with native somatostatin, octreotide LAR exerts potent inhibitory effects on the secretion of growth hormone and on various peptides of the gastroenteropancreatic endocrine system. When patients with acromegaly who show a positive response to treatment with subcutaneous octreotide 300 to 600 micrograms/day are switched to octreotide LAR 20 or 30 mg, the resulting decrease in growth hormone levels is stable and sustained. Reductions in growth hormone levels to < 5 micrograms/L for about 4 weeks are seen in 86 to 100% of patients, to < 2 to 2.5 micrograms/L in 39 to 75% and to < 1 microgram/L in 24 to 40%. Levels of insulin-like growth factor-1 (IGF-1) decrease in parallel and are often normalised with repeated drug treatment. There is no evidence of tachyphylaxis with long term therapy (up to 34 months). Treatment with octreotide LAR improves facial appearance and soft tissue thickening, and eliminates or reduces the incidence of symptoms such as headache, fatigue, arthralgia and excessive perspiration. Tumour shrinkage has been noted in some, but not all, patients receiving octreotide LAR, although this has not been widely evaluated in clinical studies. Overall, octreotide LAR is well tolerated, and the mild to moderate gastrointestinal events experienced by up to 50% of patients are of short duration and often subside with continued drug administration. The incidence of gallbladder abnormalities (sediment, sludge, microlithiasis and gallstones) increases in patients receiving long term therapy with subcutaneous octreotide, although most patients remain asymptomatic. The incidence of gallbladder abnormalities in patients receiving octreotide LAR compares favourably with that during subcutaneous administration. Glycaemic control is not usually altered during octreotide LAR treatment. In summary, octreotide continues to be the principal pharmacological option for most patients with acromegaly. Octreotide LAR offers the convenience of once-monthly administration compared with daily subcutaneous drug administration. In addition, the good efficacy and tolerability profile of octreotide LAR should enhance patient compliance and acceptability of octreotide therapy and contribute to an improvement in patient quality of life.
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PMID:Octreotide long-acting release (LAR). A review of its pharmacological properties and therapeutic use in the management of acromegaly. 909 66

Young growing animals appear to have significantly reduced "nutritional to short periods of unstressed starvation compared with adults, with resultant growth arrest and/or atrophy of diaphragm (Dia) muscle fibers. The aim of this study was to assess in an adolescent rat model of acute nutritional deprivation (ND; 72 h) the impact of insulin-like growth factor I (IGF-I), with or without added growth hormone (GH), on the cross-sectional areas (CSA) of individual Dia muscle fibers. Five groups were studied: 1) control (Ctr); 2) ND; 3) ND given IGF-I (ND/IGF-I); 4) ND given GH (ND/GH); and 5) ND given a combination of IGF-I and GH (ND/IGF-I/GH). IGF-I was given by a subcutaneously implanted osmotic minipump (200 microg/day), whereas GH was administered twice daily by a subcutaneous injection (250 microg every 12 h). Isometric contractile and fatigue properties of the Dia were determined in vitro. Forces were normalized for muscle CSA (i.e., specific force). Dia fiber type proportions were determined histochemically, and fiber CSA was quantified by using a computer-based image-processing system. Total serum IGF-I concentrations were significantly reduced in ND and ND/GH animals, compared with Ctr, and elevated in the groups receiving IGF-I. The provision of growth factors did not alter the contractile or fatigue properties of ND animals. Dia fiber type proportions were similar among the groups. In ND animals, there was a significant reduction in the CSA of types I, IIa, IIx, and IIc Dia fibers compared with Ctr. The administration of IGF-I alone or in combination with GH to ND animals significantly diminished the reduction in Dia fiber size. GH alone had no effect on Dia fiber size in ND animals. We conclude that with acute ND the peripheral resistance to the action of GH appears to be bypassed by the administration of IGF-I alone or in combination with GH.
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PMID:Effect of insulin-like growth factor I and/or growth hormone on diaphragm of malnourished adolescent rats. 910 40

It is controversial whether insulin-like growth factor I (IGF-I), growth hormone (GH), or their combination might enhance body growth and/or tissue anabolism in the well-fed animal with an intact somatotrophic axis. To assess this further, we studied four groups of adolescent rats: 1) control (Ctr), 2) GH, 3) IGF-I, and 4) GH/IGF-I. IGF-I was given via an osmotic minipump, whereas GH was injected subcutaneously for a period of 72 h. Diaphragm (Dia) contractile and fatigue properties were determined in vitro. Quantitative histochemical and morphometric analyses were performed on Dia fibers. Total serum IGF-I levels were significantly increased in the groups receiving growth factors. Although body weight increased to a greater extent in the animals receiving growth factors, a further synergistic effect was noted in the GH/IGF-I animals compared with either GH or IGF-I groups. Costal Dia mass was greater in the groups receiving growth factors. The Dia of GH/IGF-I animals was more fatigue resistant than the Dia in Ctr. The cross-sectional area of types IIa and IIx fibers were increased to a similar extent in all groups receiving growth factors compared with Ctr. Succinate dehydrogenase activity of type IIa fibers was significantly greater in the GH/IGF-I animals compared with the other groups. We conclude that the short-term provision of growth factors to well-nourished, normally growing adolescent rats can accelerate body growth and promote selective hypertrophy of predominantly type II Dia fibers.
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PMID:Anabolic influences of insulin-like growth factor I and/or growth hormone on the diaphragm of young rats. 917 66


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