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Reardon T F - - 2006
The benefits of dietary creatine supplementation on muscle performance are generally related to an increase in muscle phosphocreatine content. However, creatine supplementation may benefit endurance sports through increased glycogen re-synthesis following exercise. This study investigated the effect of creatine supplementation on muscle glycogen content, submaximal exercise fuel utilisation and endurance ...
Bröjer J - - 2006
REASONS FOR PERFORMING STUDY: The degradation of glycogen and its two forms, proglycogen (PG) and macroglycogen (MG) has been studied in horses performing different types of exercise, but no information is available about the resynthesis of PG and MG after exercise. OBJECTIVES: To determine the resynthesis of PG and MG ...
Geor R J - - 2006
REASONS FOR PERFORMING STUDY: No studies in horses have examined the effect of route of carbohydrate (glucose) administration on the rate of muscle glycogen storage following glycogen-depleting exercise. HYPOTHESIS: Glucose delivery from the gastrointestinal tract limits the rate of muscle glycogen storage following glycogen-depleting exercise. METHODS: In a crossover design, ...
McCutcheon L J - - 2006
REASONS FOR PERFORMING STUDY: Exercise is an important stimulus for the regulation of numerous metabolic functions in muscle, but there has been little investigation of the mechanism of exercise-enhanced glucose utilisation. OBJECTIVE: To examine the effects of exercise on the signalling components Akt and glycogen synthase kinase-3 (GSK3) involved in ...
Lacombe V A - - 2006
REASONS FOR PERFORMING STUDY: Exercise depletes muscle glycogen stores, which could subsequently impair performance. Muscle glycogen replenishment is determined by substrate availability. OBJECTIVES: To study the effects of feeding meals of varying glycaemic responses on blood concentrations of substrates used for glycogenesis in horses with exercise-induced glycogen depletion. METHODS: In ...
Siegel Arthur J - - 2006
Exercise-associated hyponatremia (EAH) has emerged in recent years as a life-threatening complication of endurance sports that may lead to fatal cerebral and pulmonary edema. Defined as a serum sodium concentration <135 mEq/L (1 mEq/L = 1 mmol/L), symptomatic EAH is a dilutional hyponatremia with abnormal fluid retention mediated by decreased ...
Bangsbo Jens - - 2006
It was proposed that a contraction-induced increase in tricarboxylic acid cycle intermediates (TCAI) is obligatory for the increase in muscle oxygen uptake at the start of exercise. To test this hypothesis, we measured changes in muscle TCAI during the initial seconds of intense exercise and used dichloroacetate (DCA) in an ...
Devries Michaela C - - 2006
Numerous studies from our and other laboratories have shown that women have a lower respiratory exchange ratio (RER) during exercise than equally trained men, indicating a greater reliance on fat oxidation. Differences in estrogen concentration between men and women likely play a role in this sex difference. Differing estrogen and ...
Sabapathy S - - 2006
This study examined the relationship between minute ventilation (VE), CO2 production (VCO2), and blood lactate concentration ([La-]) during incremental exercise performed with reduced muscle glycogen stores. Nine untrained female subjects (25.3+/-4.2 year) performed incremental cycling in a normal glycogen (NG) state and under conditions of reduced muscle glycogen (RG) content. ...
Jose-Cunilleras Eduard - - 2006
Fatiguing exercise substantially decreases muscle glycogen concentration in horses, impairing athletic performance in subsequent exercise bouts. Our objective was to determine the effect of ingestion of starch-rich meals after exercise on whole body glucose kinetics and muscle glycogen replenishment. In a randomized, cross-over study seven horses with exercise-induced muscle glycogen ...
Ferrara Cynthia M - - 2006
BACKGROUND: Aging is associated with insulin resistance, primarily as a result of physical inactivity and increased abdominal obesity. We hypothesized that aerobic (AEX) or resistive (RT) exercise training would result in comparable improvements in glucose disposal in older men, but that there would be different metabolic adaptations in skeletal muscle. ...
de Souza Silvia Cristina R - - 2006
The early larvae of P. paradoxus grow large but metamorphose into relatively small frogs, the diminished post-metamorphic growth producing a marked contrast between maximum larval size and adult. Thus, O(2) uptake does not appear to limit the energy expenditure on growth processes, and unlike in other anuran larvae, may not ...
Hays Nicholas P - - 2006
BACKGROUND: Previous studies have demonstrated that aerobic exercise training and weight loss have independent effects on insulin-stimulated glucose disposal (ISGD). We hypothesized that ad libitum consumption of a high-carbohydrate diet would result in weight loss and improved ISGD, and that aerobic exercise training would facilitate greater improvements in ISGD compared ...
Horton Tracy J - - 2006
The systemic flux of glycerol and palmitate [a representative nonesterified free fatty acid (NEFA)] was assessed in three different phases of the menstrual cycle at rest and during moderate-intensity exercise. It was hypothesized that circulating glycerol and NEFA turnover would be greatest in the midfollicular (MF) phase of the menstrual ...
Rogero Marcelo Macedo - - 2006
We investigated the effect of supplementation with L-glutamine and L-alanyl-L-glutamine (DIP) on the plasma and tissue glutamine concentrations of exercise-trained rats immediately and 3 hours after a single exercise session until exhaustion. Thirty-six male rats were divided into six groups, and then subdivided into groups submitted only to the exhaustion ...
Burgomaster Kirsten A - - 2006
Our laboratory recently showed that six sessions of sprint interval training (SIT) over 2 wk increased muscle oxidative potential and cycle endurance capacity (Burgomaster KA, Hughes SC, Heigenhauser GJF, Bradwell SN, and Gibala MJ. J Appl Physiol 98: 1895-1900, 2005). The present study tested the hypothesis that short-term SIT would ...
Medbø J I - - 2006
OBJECTIVE: Muscles break down glycogen to lactate during intense exercise, and in the recovery period, glycogen reappears while lactate disappears. The purpose of this study was to examine to what extent lactate is resynthesized to glycogen within the formerly active muscles themselves in man. MATERIAL AND METHODS: Fifteen healthy young ...
Koopman René - - 2006
Resistance exercise has recently been shown to improve whole-body insulin sensitivity in healthy males. Whether this is accompanied by an exercise-induced decline in skeletal muscle glycogen and/or lipid content remains to be established. In the present study, we determined fibre-type-specific changes in skeletal muscle substrate content following a single resistance ...
Chou Chia-Hau - - 2005
To elucidate the role of muscle glycogen storage on regulation of GLUT4 protein expression and whole-body glucose tolerance, muscle glycogen level was manipulated by exercise and insulin administration. Sixty Sprague-Dawley rats were evenly separated into three groups: control (CON), immediately after exercise (EX0), and 16 h after exercise (EX16). Rats ...
Morris J G - - 2005
Nine unacclimatized university sportsmen performed a prolonged, intermittent, high-intensity shuttle running test in hot (HT) (33 degrees C, dry bulb temperature, approximately 28 %, relative humidity) and moderate (MT) (17 degrees C, 63 %) environmental conditions. Subjects performed 60 m of walking, a 15-m sprint, 60 m of cruising ( ...
Bhadra N - - 2005
Our aim was to electrically activate small diameter parasympathetic fibres in the sacral anterior roots, without activating the larger somatic fibres to the external anal sphincter (EAS). Electrodes were implanted on selected roots in five adult dogs. Pressures were recorded from the rectum and EAS. Quasitrapezoidal (Qzt) pulses for selective ...
Yoshimura A - - 2005
AIM: The recruitment patterns of the intrafusal and extrafusal fibres in the soleus (SOL) and extensor digitorum longus (EDL) muscles of rats were investigated during brief-intensity exercise by assaying their glycogen content histochemically. METHODS: Six adult male rats were assigned to each of four groups that ran up a 6 ...
Benvenga S - - 2005
L-carnitine (CARN) is a water-soluble, naturally occurring quaternary amine ubiquitous in biological fluids and animal tissues; in these tissues, CARN plays an important role in energy metabolism. Skeletal muscles store about 95 % of a total of 20 g CARN contained in the adult human body, but high-intensity physical exercise ...
Zehnder Monica - - 2005
PURPOSE: Gender-specific differences in substrate utilization during exercise have been reported, typically such that women rely more on fat than men. This study investigated whether gender differences exist in the utilization of intramyocellular lipids (IMCL) and glycogen. METHODS: IMCL and glycogen, as well as total fat and carbohydrate (CHO) oxidation ...
Devries Michaela C - - 2005
CONTEXT AND OBJECTIVE: Women use less carbohydrate during endurance exercise, as compared with men. In rodents, 17beta-estradiol (E2) supplementation robustly increases lipid use and lowers muscle and liver glycogen use during exercise. E2 supplementation has been found to influence substrate selection by decreasing glucose rate of appearance (Ra), disappearance (Rd), ...
van Loon L J C - - 2005
AIMS/HYPOTHESIS: In the present study, we investigated the consequences of adipose tissue lipolytic inhibition on skeletal muscle substrate use in type 2 diabetic patients. MATERIALS AND METHODS: We studied ten type 2 diabetic patients under the following conditions: (1) at rest; (2) during 60 min of cycling exercise at 50% ...
Essén-Gustavsson Birgitta - - 2005
OBJECTIVE: To investigate influence of the Rendement Napole (RN-) mutation on proglycogen (PG) and macroglycogen (MG) content in skeletal muscles before and after exercise and evaluate glycogen concentrations within various muscle fiber types. ANIMALS: 5 pigs with the RN- mutation and 3 noncarrier pigs. PROCEDURE: Pigs performed 2 exercise tests ...
Braun Barry - - 2005
Compared with women, men use proportionately more carbohydrate and less fat during exercise at the same relative intensity. Estrogen and progesterone have potent effects on substrate use during exercise in women, but the role of testosterone (T) in mediating substrate use is unknown. The purpose of this investigation was to ...
Pederson Bartholomew A - - 2005
Skeletal muscle glycogen is considered to be an important source of energy for contraction and increasing the level of the glucose polymer is generally thought to improve exercise performance in humans. A genetically modified mouse model (GSL30), which overaccumulates glycogen due to overexpression of a hyperactive form of glycogen synthase, ...
Jakovljevic V Lj - - 2005
The aim of this study was to assess the changes of coronary flow (CF) and nitrite outflow under inhibition of nitric oxide synthase (NOS) by Nomega-nitro-L-arginine monomethyl ester (L-NAME) or lipoxygenase (LOX) induced by nordihydroguaiaretic acid (NDGA) in isolated rat heart. The hearts of male Wistar albino rats (n=18, age ...
Creer Andrew - - 2005
Two pathways that have been implicated for cellular growth and development in response to muscle contraction are the extracellular signal-regulated kinase (ERK1/2) and Akt signaling pathways. Although these pathways are readily stimulated after exercise, little is known about how nutritional status may affect stimulation of these pathways in response to ...
Shearer Jane - - 2005
Glycogenin is the self-glycosylating protein primer that initiates glycogen granule formation. To examine the role of this protein during glycogen resynthesis, eight male subjects exercised to exhaustion on a cycle ergometer at 75% Vo2 max followed by five 30-s sprints at maximal capacity to further deplete glycogen stores. During recovery, ...
Deviller G - - 2005
European sea bass were reared in three different systems: one flow-through (FTS), one recirculating (RAS), and one recirculating with a high-rate algae pond (RAS + HRAP). After 1 year of rearing, the final fish weight was 15% lower in the RAS compared to the FTS. The accumulation of a growth-inhibiting ...
Shearer Jane - - 2005
Glycogenolysis results in the selective catabolism of individual glycogen granules by glycogen phosphorylase. However, once the carbohydrate portion of the granule is metabolized, the fate of glycogenin, the protein primer of granule formation, is not known. To examine this, male subjects (n = 6) exercised to volitional exhaustion (Exh) on ...
Petibois Cyril - - 2005
This study was designed to describe changes in plasma fatty acyl moieties during a 2-h endurance exercise. Sixteen endurance-trained subjects cycled 2 h at 55% of maximal power output and capillary blood was sampled every 15 min. Fourier-transform infrared (FT-IR) spectrometry was used to determine correlated changes between plasma fatty ...
Andersson Ulrika U Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Campus, DuCane Road, London W12 0NN, - - 2005
Recent studies have demonstrated that AMP-activated protein kinase (AMPK) in the hypothalamus is involved in the regulation of food intake. Because exercise is known to influence appetite and cause substrate depletion, it may also influence AMPK in the hypothalamus. Male rats that either rested or ran for 30 or 60 ...
Morifuji Masashi - - 2005
We investigated the effect of different types of dietary protein on glycogen content in liver and skeletal muscle of exercise-trained rats. Twenty-four male Sprague-Dawley rats (approximately 100 g; n 6 per group) were divided into sedentary or exercise-trained groups with each group being fed either casein or whey protein as ...
Cunha Tatiana Sousa - - 2005
To increase tissue glycogen content many athletes use anabolic androgenic steroids (AAS). However, the literature concerning the effects of androgens on glycogen metabolism is conflicting. This study aimed to determine the influence of training and AAS on body weight (bw), triglycerides, glucose, tissue glycogen and transaminases levels. Male Wistar rats, ...
McInerney Patrick - - 2005
PURPOSE: It is not known whether it is possible to repeatedly supercompensate muscle glycogen stores after exhaustive exercise bouts undertaken within several days. METHODS: We evaluated the effect of repeated exercise-diet manipulation on muscle glycogen and triacylglycerol (IMTG) metabolism and exercise capacity in six well-trained subjects who completed an intermittent, ...
Mundy H R - - 2005
Glycogen storage disease type I (GSD-I) is an inherited disorder of carbohydrate metabolism. Hepatic glucose-6-phosphatase is deficient, leading to impaired gluconeogenesis and glycogenolysis. Patients prevent fasting hypoglycemia by frequent feeds of low glycemic index foods. Normal muscle does not contain glucose-6-phosphatase, and GSD-I is usually classified as a hepatic glycogenosis. ...
Rauch H G L - - 2005
INTRODUCTION: In this study we examined the pacing strategy and the end muscle glycogen contents in eight cyclists, once when they were carbohydrate loaded and once when they were non-loaded. METHODS: Cyclists completed 2 hours of cycling at approximately 73% of maximum oxygen consumption, which included five sprints at 100% ...
Ruby B C - - 2005
The purpose of this study was to determine the effects of ingesting an oral supplement containing 4-Hydroxyisoleucine (4-OH-Ile, isolated from fenugreek seeds [Trigonella foenum-graecum]) with a glucose beverage on rates of post-exercise muscle glycogen resynthesis in trained male cyclists. Following an overnight fast (12 hr), subjects completed a 90-minute glycogen ...
Raja Ghazala - - 2004
It is not clear whether the amount of accumulated lactate is the main factor limiting muscle glycogen accumulation during recovery from an intense sprint performed by previously active fasted laboratory rats. To address this question, groups of fasted rats swam at moderate intensity for 30 min, each animal with a ...
Stellingwerff Trent - - 2005
This study compared the effects of inspiring either a hyperoxic (60% O(2)) or normoxic gas (21% O(2)) while cycling at 70% peak O(2) uptake on 1) the ATP derived from substrate phosphorylation during the initial minute of exercise, as estimated from phosphocreatine degradation and lactate accumulation, and 2) the reliance ...
Brown Angus M - - 2004
We tested the hypothesis that astrocytic glycogen supports axon function under both pathological and physiological conditions. Functional activity of the rat (RON) or mouse optic nerve (MON), representative central white matter tracts, was assessed electrophysiologically as the area under the supramaximal compound action potential (CAP). During aglycaemia the CAP area ...
Kohler Götz - - 2004
The purpose of this study was to determine for the first time by repeated non-invasive 13C-NMR spectrometry whether blood lactate concentration affects glycogen reduction in non-exercising muscle during prolonged (6 h) physical exercise in healthy adult males. Such an effect would indirectly show that glycogenolysis independent of nervous activation occurs ...
El Rammouz R - - 2004
The biochemical determinism of ultimate pH (pHu) was studied in the pectoralis muscle of broiler chickens. Thirty birds of 3 genetic types (a fast-growing standard (FG), a slow-growing French "Label Rouge" (SG), and a heavy line type (HL)) were kept under conventional breeding methods until the usual marketing age (6, ...
Schaart Gert - - 2004
Simultaneous analyses of glycogen in sections with other subcellular constituents within the same section will provide detailed information on glycogen deposition and the processes involved. To date, staining protocols for quantitative glycogen analyses together with immunofluorescence in the same section are lacking. We aimed to: (1) optimise PAS staining for ...
Arkinstall Melissa J - - 2004
To date, the results of studies that have examined the effects of altering preexercise muscle glycogen content and exercise intensity on endogenous carbohydrate oxidation are equivocal. Differences in the training status of subjects between investigations may, in part, explain these inconsistent findings. Accordingly, we determined the relative effects of exercise ...
Shearer Jane - - 2004
Although it is often viewed as a homogenous substrate, glycogen is comprised of individual granules or 'glycosomes' that vary in their composition, subcellular localization, and metabolism. These differences result in additional levels of regulation allowing granules to be regulated individually or regionally within the cell during both rest and exercise.
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