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Results 451 - 500 of 788
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Litvinova L - - 1995
In Wistar rats after swimming for 3 h, the glycogen level remained low in the liver during a period of 7 h. When sucrose was administered immediately after exercise, the liver glycogen content increased rapidly. From the 3rd to the 5th postexercise hour a secondary reduction was observed in hepatic ...
Hargreaves M - - 1995
To examine the effects of alterations in preexercise muscle glycogen availability on glycogenolysis and glucose uptake during exercise, 12 active but untrained men [22.8 +/- 1.6 (SE) yr, 71.7 +/- 2.0 kg, peak pulmonary oxygen uptake 3.85 +/- 0.16 l/min] were studied during 40 min of cycle ergometer exercise at ...
van Baak M A - - 1995
Twelve healthy male volunteers cycled to exhaustion at a workload corresponding to 70% of maximal aerobic power after administration of 80 mg of the beta 1+2-adrenoceptor antagonist propranolol and after administration of placebo by mouth. Exercise times until exhaustion were 39 +/- 7 and 86 +/- 7 min in the ...
Dossett-Mercer J - - 1994
To examine the effect of exercise on sarcoplasmic reticulum function in muscle tissue of different fibre composition, adult male Wistar rats weighing 388 +/- 23 g (x +/- SE) ran intermittently on a treadmill until fatigue. Fatigue was induced by 15-20 min of running performed at 52 m/min on an ...
Vukovich M D - - 1994
This study investigated the effects of L-carnitine supplementation on muscle carnitine and glycogen content during submaximal exercise (EX). Triglycerides were evaluated by a fat feeding (90 g fat) and 3 h later subjects cycled for 60 min at 70% VO2max (CON). Muscle biopsies were obtained preexercise and after 30 and ...
Price T B TB Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT - - 1994
To determine whether glycogen turnover occurs during prolonged low-intensity exercise, five subjects performed plantar flexion of the right leg at 15% MVC for 5 h. At rest and during the initial 2.5 h of exercise gastrocnemius glycogen was monitored in both legs with natural abundance 13C NMR. At 2.5 h ...
Greenhaff P L - - 1994
1. Muscle biopsy samples were obtained from the vastus lateralis of six healthy volunteers before and after 30 s of treadmill sprinting. A portion of each biopsy sample was used for mixed-fibre metabolite analysis. Single fibres were dissected from the remaining portion of each biopsy and were used for ATP, ...
Coleman E - - 1994
Athletes often train or compete in athletic events that significantly reduce muscle and liver glycogen reserves. Carbohydrate ingestion before or during endurance exercise enhances performance by maintaining blood glucose levels and carbohydrate utilization. Also, an adequate intake of carbohydrate following endurance exercise helps to restore muscle and liver glycogen. This ...
Braiden R W - - 1994
Because cocaine causes a rapid sympathetic response and central euphoria, we tested whether it would improve endurance or alter carbohydrate metabolism during high-intensity activity. Thirty male rats (10 animals/group) were injected intraperitoneally with either saline (S) or one of two doses of cocaine-HCl (12.5 (C-1) or 20.0 (C-2) mg.kg-1 b.w.). ...
Anatskaya O V - - 1994
Two alternate hypotheses explaining the causes of mammalian liver polyploidy have been tested by means of statistical analysis of more than 30 placental species. According to the first (general) hypothesis, the omission of mitosis is beneficial in rapidly growing and differentiating tissues that should early perform their specialized functions (economy ...
Magnusson I - - 1994
Whether liver glycogen synthesis and breakdown occur simultaneously during net glycogen synthesis was assessed in fed and fasted healthy humans. The peak intensity of the carbon-1 (C1) resonance of the glycosyl units of glycogen was monitored with 13C nuclear magnetic resonance spectroscopy during [1-13C]glucose infusion followed by unlabeled glucose infusion. ...
Sumida K D - - 1994
The effects of endurance training (running 30 m/min, 10% grade for 90 min, 5 days/wk for 12 wk) on skeletal muscle glucose uptake during steady-state exercise (running 20 m/min) were studied in fed rats. A bolus injection of 2-[1,2-3H]deoxyglucose was administered to assess the glucose metabolic index (R'g), an indicator ...
Schneiter P - - 1994
In vivo glycogen kinetics was estimated with the simultaneous use of indirect calorimetry and tracer technology in healthy humans during 24-h periods with low or moderate physical activity (1 or 3 exercise sessions each day). Two 13C-carbohydrates meals were administered at 9.30 a.m. and 1.30 p.m., and one 12C-carbohydrates meal ...
Green S - - 1994
The degree to which the y-intercept (Y-int) of the linear regression of maximal work output on exercise duration represented anaerobic capacity was determined in ten well-trained male cyclists [peak oxygen uptake (VO2peak) = 69.8 (SD 4.2) ml.kg-1.min-1]. Each cyclist performed three exhausting cycle sessions on separate occasions; the mean exercise ...
Hellsten-Westing Y - - 1994
The exchange of purines in liver and active skeletal muscle with short-term exhaustive exercise was investigated. Eight male subjects performed two similar 10-min bouts of exhaustive supine cycling, separated by 75 min of rest. Immediately after termination of the second bout, a tourniquet was applied to the upper part of ...
Varnier M - - 1994
The aim of this study was to investigate whether, when muscle glycogen is reduced, a pre-exercise infusion of branched-chain amino acids (BCAA) modifies exercise performance or the metabolic and respiratory responses to incremental exercise. Six moderately trained volunteers took part in the following protocol on two occasions. On day 1, ...
Price T B - - 1994
To study the effects of glycogen depletion and insulin concentration on glycogen synthesis, gastrocnemius glycogen was measured with 13C-nuclear magnetic resonance at 4.7 T after exercise. Subjects performed single-leg toe raises to deplete gastrocnemius glycogen to 75, 50, or 25% of resting concentration (protocol I). Insulin dependence of glycogen synthesis ...
Bloch G G Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut - - 1994
Time courses of the glycogen synthesis rate and of the glucose 6-phosphate (G-6-P) concentration after an electrically induced exercise were followed in the anesthetized rat gastrocnemius by in vivo 13C and 31P nuclear magnetic resonance (NMR) spectroscopy, respectively. The ratio of glycogen synthase I to glycogen synthase I and D ...
Dyck D J - - 1993
Six male subjects received either a saline (control) or Intralipid infusion during 30 min rest and 15 min cycling at 85% maximal O2 uptake (VO2max) to examine the regulation of fat-carbohydrate interaction (glucose-fatty acid cycle) in skeletal muscle. Muscle biopsies were sampled immediately before and at 3 and 15 min ...
Burge C M - - 1993
Eight international class lightweight rowers were examined to determine the efficacy of rehydrating with water following 24 h of dehydration on body fluid balance, metabolic function, and rowing performance. The rowers performed a maximal rowing trial on a Gjessing rowing ergometer (4200 revs, 3-kg resistance) while euhydrated (ET) and following ...
Yoshino M - - 1993
1. Role of NADP-glutamate dehydrogenase in the depletion of citrate was analyzed using permeabilized yeast cells. 2. Citrate was converted to 2-oxoglutarate, which was then metabolized to glutamate by NADP-glutamate dehydrogenase in the presence of ammonium ion. 3. Formation of 2-oxoglutarate plus glutamate was in good agreement with the concentration ...
Mehrani H - - 1993
To analyze the mechanisms of glycogen phosphorylase control in organs of the rainbow trout Oncorhynchus mykiss, activities of glycogen phosphorylase kinase (GPK) and cAMP-dependent protein kinase (PKA), as well as levels of cAMP, were quantified. The complete cascade for activating glycogen phosphorylase was present in trout organs and all components ...
Craig B W - - 1993
Athletic competition requires great energy expenditure and the ability to maintain performance depends on an adequate supply of metabolic fuels, which has led to the use of dietary supplements. Much of the data concerning fructose supplementation is contradictory in nature, but it shows that fructose feeding before or during exercise ...
Putman C T - - 1993
Pyruvate dehydrogenase activity (PDHa) and acetyl group accumulation were examined in human skeletal muscle at rest and during exercise after different diets. Five males cycled at 75% of maximal O2 uptake (VO2 max) to exhaustion after consuming a low-carbohydrate diet (LCD) for 3 days and again 1-2 wk later for ...
Marchini J S - - 1993
The in vivo rate of conversion of phenylalanine to tyrosine (PheOH) can be estimated using combinations of stable isotope-labeled phenylalanine and tyrosine. We have compared in four healthy adult men the rates of phenylalanine conversion to tyrosine based on the following pairs of primed, continuous tracer infusions administered simultaneously: (1) ...
Zinker B A - - 1993
We hypothesized that augmented responses of glucoregulatory hormones in iron deficiency would enhance liver and muscle glycogenolysis, leading to increased gluconeogenic precursor (lactate) supply and upregulation of hepatic gluconeogenesis. Female weanling rats were randomly placed on either a mildly iron-deficient (-Fe; 15 mg Fe/kg diet) or an iron-sufficient (+Fe; 50 ...
Aragón-Vargas L F - - 1993
Early studies agree that fasting is detrimental to overall physical performance and to endurance performance in humans; however, a study in rats reported an ergogenic effect where time to exhaustion was increased by a glycogen-sparing effect of elevated free fatty acids in blood resulting from a 24-hour fast. Later studies ...
Rooney T P - - 1993
The effect of 17 beta-estradiol 3-benzoate (10 micrograms.01 ml of sunflower oil-1 x 100 g body wt-1) on the temporal pattern of exercise-induced tissue glycogen depletion and tissue lipid availability during submaximal treadmill running was determined in male rats. Animal were administered estradiol or oil for 5 days and were ...
Medbø J I - - 1993
High-intensity exercise results in a large breakdown of glycogen. The glycogen lost may reappear as hexose phosphates, lactate, or it may be fully oxidized. Part of the lactate produced may be transferred from muscle to blood. There is, however, incomplete information on the relative importance of each endpoint of glycogen ...
Romijn J A - - 1993
Stable isotope tracers and indirect calorimetry were used to evaluate the regulation of endogenous fat and glucose metabolism in relation to exercise intensity and duration. Five trained subjects were studied during exercise intensities of 25, 65, and 85% of maximal oxygen consumption (VO2max). Plasma glucose tissue uptake and muscle glycogen ...
Burke L M - - 1993
The effect of the glycemic index (GI) of postexercise carbohydrate intake on muscle glycogen storage was investigated. Five well-trained cyclists undertook an exercise trial to deplete muscle glycogen (2 h at 75% of maximal O2 uptake followed by four 30-s sprints) on two occasions, 1 wk apart. For 24 h ...
Trudeau F - - 1993
The ergogenic effect of aspartate salts on performance during prolonged exercise is still controversial. Potential mechanisms of the suggested ergogenic effect of aspartate on exercise performance are a sparing of muscle glycogen stores or its faster resynthesis during exercise. The purpose of this study was to determine whether aspartate causes ...
Graham T - - 1993
We investigated the impact of repeated, high-intensity exercise on NH3 metabolism using the single-leg knee extensor model. The muscle glycogen level would be lowered by the initial exercise and low glycogen may stimulate NH3 production independent of any other effects of previous exercise. Therefore a high muscle glycogen condition was ...
Decombaz J - - 1993
The effect of L-carnitine on energy metabolism at a high lipolytic flux was studied. Nine healthy male subjects received L-carnitine (CARN) (3 g.d-1) for 7 d, or a placebo (CONT), both with Ca pentothenate. The treatment increased resting nitrogen excretion slightly (+15%, P < 0.02). After an overnight fast, the ...
Dernbach A R - - 1993
In untrained subjects, strenuous exercise provokes the appearance of oxidant stress markers in blood and muscle. On the other hand, trained muscle is resistant to oxidant stress unless exercise challenges the muscle glycogen supply. It is not known whether chronic high-intensity exercise alters the susceptibility of skeletal muscle to oxidant ...
Nazar K - - 1993
The effect of exhaustive treadmill exercise on mitochondrial density (MD) and ultrastructural changes in quadriceps femoris muscle was studied in 7 normal, healthy, male mongrel dogs (2-4 years, 15-20 kg) before and after restricted activity (RA) (2 months for 5 dogs, 5 months for 2 dogs), and following a subsequent ...
Doyle J A - - 1993
Eccentric contractions appear to reduce muscle glycogen replenishment during the 1- to 10-day period after exercise. The main purpose of this study was to determine whether consuming a large amount of carbohydrate (1.6 g.kg-1.h-1) during the 4 h after glycogen-reducing exercise would produce different patterns of glycogen replenishment in human ...
Pascoe D D - - 1993
The purpose of this investigation was to determine the influence of post-exercise carbohydrate (CHO) intake on the rate of muscle glycogen resynthesis after high intensity weight resistance exercise in subjects not currently weight training. In a cross-over design, eight male subjects performed sets (mean = 8.8) of six single leg ...
Zendzian-Piotrowska M - - 1993
The rats were made to run daily to exhaustion, for 28 days at a speed of 1,200 m.h-1 on a treadmill set at a gradient of +10 degrees. The training increased the time of running to exhaustion [184 (SD 49) and 308 (SD 28) min on the 1st and 28th ...
Jinnai K - - 1993
A 28-year-old male with glycogenosis type V associated with continuous hyperuricemia during mild daily activities is reported. An aerobic exercise test using a bicycle ergometer revealed that purine metabolites, i.e., ammonia, inosine, hypoxanthine and xanthine, were transiently increased by the exercise and that a subsequent increment in uric acid continued ...
Murgatroyd P R - - 1993
Glycogen forms the smallest yet most labile energy substrate store. Therefore studying carbohydrate flux may be crucial to understanding the regulation of energy balance. Indirect calorimetry has been used to measure carbohydrate oxidation overnight and during exercise in nine fasted subjects. Overnight carbohydrate oxidation (averaging 2.85 +/- 0.8 g h-1) ...
Sonko B J - - 1993
A non-invasive method for studying the dynamics of post-exercise carbohydrate storage by means of whole-body calorimetry and 13CO2 breath tests is described. Seven untrained glycogen-depleted subjects were offered naturally 13C-labelled high carbohydrate meals (97% by energy) at 30 min intervals for 5 h and asked to consume as much as ...
Sherman W M - - 1993
The effects of moderate- or high-carbohydrate diets on muscle glycogen and performance in runners and cyclists over 7 consecutive days of training were determined. Muscle biopsies were performed on 4 separate days before exercise for 1 h at 75% peak oxygen consumption (VO2) followed by five, 1-min sprints. After the ...
Constantin-Teodosiu D - - 1992
Seven subjects cycled to exhaustion [58 +/- 7 (SE) min] at approximately 75% of their maximal oxygen uptake (VO2max). Needle biopsy samples were taken from the quadriceps femoris muscle at rest, after 3, 10, and 40 min of exercise, at exhaustion, and after 10 min of recovery. After 3 min ...
Sinoway L I - - 1992
Post leg exercise circulatory arrest (PLE-CA) raises blood pressure (BP) and reduces peak forearm vascular conductance (C). This reflex is evoked by activation of muscle afferents that are often sensitive to lactic acid. We tested the hypothesis that lactic acid reductions induced by muscle glycogen depletion would attenuate the lower-limb ...
Sherman W M - - 1992
1) During training for and competition in endurance exercise athletes often significantly reduce both liver and muscle glycogen reserves. 2) Replenishment of muscle glycogen probably occurs preferentially over the replenishment of liver glycogen after exercise. 3) Muscle and liver glycogen can be replenished within 24 h after exercise provided adequate ...
Yan Z - - 1992
Subjects cycled at a work load calculated to elicit 75% of maximal oxygen uptake on two occasions: the first to fatigue (34.5 +/- 5.3 min; mean +/- SE), and the second at the same workload and for the same duration as the first. Biopsies were obtained from the quadriceps femoris ...
Nazar K - - 1992
To study physiological effects of restricted activity (RA) and subsequent retraining, 10 male mongrel dogs (1-5 years) performed a submaximal exercise endurance test on a treadmill (12 degrees slope, 1.6 m.s-1) during kennel control, after 8 weeks of cage (40 cm-w x 80 cm-h x 110 cm-l) confinement, and after ...
Hargreaves M - - 1992
Six men were studied during 40 min of cycling exercise to examine the relationship between leg glucose uptake and muscle glycogen concentration. Exercise resulted in significant increases in leg glucose uptake, while muscle glycogen and arterial blood glucose concentrations declined. Arterial plasma insulin levels did not change significantly. There was ...
Widrick J J - - 1992
This study examined the time course of glycogen accumulation in skeletal muscle depleted by concentric work and subsequently subjected to eccentric exercise. Eight men exercised to exhaustion on a cycle ergometer [70% of maximal O2 consumption (VO2max)] and were placed on a carbohydrate-restricted diet. Approximately 12 h later they exercised ...
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