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Green H J - - 1991
A short-term training program involving 2 h of daily exercise at 59% of peak O2 uptake (VO2max) repeated for 10-12 consecutive days was employed to determine the significance of adaptations in energy metabolic potential on alterations in energy metabolism and substrate utilization in working muscle. The initial VO2max determined before ...
Aussedat J - - 1991
Twenty millimolar and 2 mM uridine triphosphate and 2 mM uridine were injected intra-arterially into rat leg muscles during a 20 min period of intense exercise and during the recovery phase (20 min). Administration of 20 mM uridine triphosphate during exercise, provoked a complete depression of muscle contractility. On the ...
Friman G - - 1991
The present study was performed to determine whether alterations in fuel reserves or energy substrate utilization might explain the performance decrements that occur in bacterial infections. Male Fisher-Dunning rats were studied at 24, 48, and 72 h after inoculation with Streptococcus pneumoniae. Rats were either sedentary or subjected to a ...
Price T B - - 1991
Glycogen metabolism in exercising gastrocnemius muscles was examined by natural abundance 13C nuclear magnetic resonance (NMR) spectroscopy. Five-minute 13C-NMR measurement of muscle glycogen had a reproducibility of +/- 6.5% (+/- 4.8 mM). Experiments were performed on healthy fed male and female subjects. Two protocols were followed. 1) Subjects performed plantar ...
Neufer P D - - 1991
The purpose of this investigation was to examine the effects of moderate hypohydration (HY) on skeletal muscle glycogen resynthesis after exhaustive exercise. On two occasions, eight males completed 2 h of intermittent cycle ergometer exercise (4 bouts of 17 min at 60% and 3 min at 80% of maximal O2 ...
Friedman J E - - 1991
With the cessation of exercise, glycogen repletion begins to take place rapidly in skeletal muscle and can result in glycogen levels higher than those present before exercise. Understanding the rate-limiting steps that regulate glycogen synthesis will provide us with strategies to increase the resynthesis of glycogen during recovery from exercise, ...
Bangsbo J - - 1991
1. Intramuscular glyconeogenesis from lactate after intense exercise was examined by using the one-legged knee extension model which enables evaluation of metabolism in a well-defined muscle group. 2. In seven subjects measurements of leg blood flow and arterial-venous differences of various substrates were performed in individuals after intense, exhaustive knee ...
Wasserman D H - - 1991
The role of the gut and liver in nitrogen metabolism was studied during rest, 150 minutes of moderate-intensity treadmill exercise, and 90 minutes of recovery in 18 hour-fasted dogs (n = 6). Dogs underwent surgery 16 days before an experiment for implantation of catheters in a carotid artery and in ...
Conlee R K - - 1991
This study was designed to test the hypothesis that cocaine (C) alters the normal physiological responses to exercise. Male rats were injected with saline (S) or C (12.5 mg/kg) either intravenously (iv) or intraperitoneally (ip). After injection the animals were allowed to rest for 30 min or were run on ...
McLellan T M - - 1991
Previous research has shown that the rate of muscle glycogen utilization is related to exercise intensity expressed relative to maximal aerobic power (%VO2max). The purpose of this study was to compare the relationship between glycogen utilization and %VO2max to that between glycogen utilization and intensity expressed relative to the onset ...
Green H J - - 1991
Endogenous muscle glycogen represents a primary fuel source during large muscle group activity in the human. The depletion of this fuel source during submaximal exercise at intensities ranging between 60 and 85% of maximal aerobic power (Vo2max) is widely believed to be the cause of an inability to sustain exercise. ...
Ivy J L - - 1991
The importance of carbohydrates as a fuel source during endurance exercise has been known for 60 years. With the advent of the muscle biopsy needle in the 1960s, it was determined that the major source of carbohydrate during exercise was the muscle glycogen stores. It was demonstrated that the capacity ...
Robergs R A - - 1991
This study investigated the effects of preliminary exercise (warm-up) on glycogen degradation and energy metabolism during intense cycle ergometer exercise. After determination of VO2max, six male subjects were randomly assigned to perform warm-up (WU) and no warm-up (NWU) trials incorporating a 2 min standardized sprint ride (SR) at 120% of ...
Weststrate J A - - 1990
In 10 young, normal-weight subjects, the effects were investigated of carbohydrate overfeeding and prior glycogen-depleting exercise on resting metabolic rate (RMR) and diet-induced thermogenesis (DIT). Subjects were kept on controlled diets in a crossover design for two periods of 8 days, with a 1-week interval in between. During the last ...
Abernethy P J - - 1990
Skeletal muscle adapts to the stress of endurance and sprint exercise and training. There are 2 main types of skeletal muscle fibre--slow twitch (ST) and fast twitch (FTa, FTb, FTc). Exercise may produce transitions between FT and ST fibres. Sprint training has decreased the proportion of ST fibres and significantly ...
Sahlin K - - 1990
Seven subjects cycled to fatigue [75 +/- 5 (SE) min] at a work load corresponding to approximately 75% of their maximal oxygen uptake. Biopsies were taken from the quadriceps femoris muscle at rest and during exercise. Muscle glycogen decreased from a preexercise level of 445 +/- 33 mmol glucosyl units/kg ...
Brammer M J - - 1990
The carbachol and adrenaline-mediated accumulation of inositol monophosphate isomers in rat cortical prisms has been studied using a commonly employed experimental protocol involving preincubation with myo-[2-3H]-inositol and subsequent incubation with agonists in the presence of 10 mM LiCl. Inositol phosphate isomers have been analysed by HPLC and identified by comparison ...
Sahlin K - - 1990
Two patients with muscle phosphorylase deficiency [McArdle's disease (McA)] were studied during bicycle exercise at 40 (n = 2) and 60 W (n = 1). Peak heart rate was 170 and 162 beats/min, corresponding to approximately 90% of estimated maximal heart rate. Muscle samples were taken at rest and immediately ...
Green H J - - 1990
Using the glycogen depletion technique, we have examined utilization of specific fibre types during prolonged submaximal exercise to investigate the recruitment pattern employed by the central nervous system to sustain force generation in the face of a progressive glycogen depletion. Six male subjects (Vo2 max, 52.8 +/- 2.5 mL.kg-1.min-1, mean ...
Pascoe D D - - 1990
The purpose of this study was to examine differences in muscle glycogen storage during three successive days of running or cycling. In a crossover design, seven male subjects performed two 3-d trials of either running (trial R) or cycling (trial C) for 60 min at 75% VO2max. Biopsy samples were ...
Costill D L - - 1990
Eight men performed 10 sets of 10 eccentric contractions of the knee extensor muscles with one leg [eccentrically exercised leg (EL)]. The weight used for this exercise was 120% of the maximal extension strength. After 30 min of rest the subjects performed two-legged cycling [concentrically exercised leg (CL)] at 74% ...
Nordheim K - - 1990
The influence of high lactate concentration on glycogen metabolism in active type I and inactive type II fibres was investigated. High muscle lactate concentration (26.7 +/- 1.4 mmol kg-1 wet wt) was achieved by three bouts (2 min duration) of bicycle exercise at 112% Vo2 max. Exercise was continued at ...
Bak J F - - 1990
The present study was undertaken to elucidate aspects of the regulatory mechanisms leading to enhanced glucose metabolism and insulin sensitivity of muscle after physical exertion. Biopsies were obtained from the vastus lateralis muscle of healthy volunteers before and after 60 min of bicycle exercise at 60% of their maximal aerobic ...
Johansson C - - 1990
Consumption and restoration of muscle glycogen and changes in anabolic and catabolic steroid hormones were analyzed in five male elite orienteers during and after an orienteering competition. The magnitude of glycogen consumption and pronounced increase in serum-cortisol during the orienteering race reflect the great muscular output demands during forest running. ...
Décombaz J E - - 1990
To test the effect of L-carnitine on glycogen sparing when fat oxidation is increased, 100 mg/kg/d were given to rats orally for 3 days, resulting in 1.8-fold higher muscle carnitine levels. Even when FFA were raised by heparin-stimulated lipolysis, the rate of glycogen degradation was not reduced during exercise.
Brouns F - - 1990
In a number of individual cycling tests lasting 2.5-5 h with alternating exercise intensities of 50%-85% of maximal working capacity, it was observed that plasma ammonia levels may rise above 250 mumol/l when reaching exhaustion, while lactate levels remain relatively low. Acute quantitative ammonia production during intensive endurance exercise may ...
Curi R - - 1990
In this study, rats under meal-feeding up to four weeks were submitted to a sudden exercise (swimming) to evaluate the effects of a behavior that requires mobilization of a large amount of energy on some physiological parameters already changed due to the chronic food-restriction. During exercise meal-fed rats: 1) increase ...
Uchiyama Y - - 1990
In standard textbooks of histology, hepatocyte structure is described as being, for the most part, static. However, more than 50 years ago, it was reported that the glycogen content of rabbit hepatocytes varies significantly over 24 h. Since then, numerous investigators have confirmed this phenomenon in a variety of animals ...
Wagenmakers A J - - 1990
Patients with McArdle's disease (myophosphorylase deficiency) cannot use muscle glycogen as an energy source during exercise. They therefore are an ideal model to learn about the metabolic adaptations which develop during endurance exercise leading to glycogen depletion. This review summarizes the current knowledge of ammonia and amino acid metabolism in ...
Myers J - - 1990
Exogenous fructose 1,6-diphosphate (FDP), a glycolytic intermediate, has recently been demonstrated to accelerate ATP production, prevent glycogen breakdown, stimulate glycogen synthesis, and synthesize free fatty acids in animals and humans. To assess the effects of FDP on the hormonal and metabolic response to exercise, ten trained males (34 +/- 7 ...
Cerretelli P - - 1990
The use of supplementary L-carnitine by athletes has become rather widespread over the recent years even in the absence of unequivocal results from human experimental studies that might support this practice. To justify the above procedure, the most commonly purported reasons are that L-carnitine administration could hypothetically: 1. increase lipid ...
Essén-Gustavsson B - - 1990
Nine bodybuilders performed heavy-resistance exercise activating the quadriceps femoris muscle. Intermittent 30-s exhaustive exercise bouts comprising 6-12 repetitions were interspersed with 60-s periods for 30 min. Venous blood samples were taken repeatedly during and after exercise for analyses of plasma free fatty acid (FFA) and glycerol concentration. Muscle biopsies were ...
Boninsegna A - - 1990
Skeletal muscle, liver and heart glycogen variations, induced by swimming in thermal water (at 35 degrees C) as a model of physical exercise for clinical use, were studied. Muscle and liver glycogen moderately decreases after a 30-min period of swimming and comes near to depletion after 60 min. Heart glycogen ...
Tarnopolsky L J - - 1990
The effects of gender on substrate utilization during prolonged submaximal exercise were studied in six males and six equally trained females. After 3 days on a controlled diet (so that the proportions of carbohydrate, protein, and fat were identical), subjects ran on a treadmill at a velocity requiring an O2 ...
Staron R S - - 1989
Intramuscular lipid content was investigated in muscle biopsies from 10 well-trained endurance athletes before, immediately after, and 1, 3, 5, and 7 days after a marathon. Diets were controlled throughout the entire period of the study. Triglyceride content was ultrastructurally determined by the use of stereological methods. The volume percent ...
Conlee R K - - 1989
Cocaine is a potent sympathomimetic drug, and has been implicated as a causative factor in cardiac seizures. However, little is known about the effect of the drug on myocardial substrate utilization. In the present study, rats were injected intravenously with saline solution or one of three doses of cocaine-HCl (1.25, ...
van der Vusse G J - - 1989
Thirty-four nonathletic volunteers (23 males and 11 females) were subjected to a training program aimed at completing a marathon run within 18-20 months after the onset of training. During the course of the training the content of ATP, creatine phosphate, GTP, GDP, NAD+, purine bases, and glycogen in biopsyspecimens of ...
Symons J D - - 1989
The purpose of this study was to evaluate the effects of glycogen availability on short-term, high-intensity exercise performance. Eight males completed performance evaluation tasks (PET) consisting of maximum isokinetic strength and endurance, isometric strength, and electrically evoked force of the leg extensors, twice during each of two conditions. On day ...
Vøllestad N K - - 1989
The rate of glycogen resynthesis was examined in different muscle fibre types after prolonged exhaustive exercise. Six subjects exercised to exhaustion at 75% of VO2 max, and muscle biopsies were taken after 0, 90 and 180 min of recovery. Glucose drinks (1.4, 0.7 and 0.7 g kg-1 body wt) were ...
Hatta H - - 1989
The purpose of this study was to investigate the main site of removal of blood lactate and glucose and which is the more important substrate for muscle glycogen resynthesis in rats after short-term strenuous exercise, to exhaustion. Male Wistar rats ran to exhaustion at a speed of 70-100m.min-1. Immediately after ...
Nicklas B J - - 1989
Six eumenorrheic females (age = 26.3 +/- 2.4 yrs; X +/- SE) exercised until exhaustion (EE; 70% VO2max) at the midluteal (LP, 7-8 days after ovulation) and midfollicular (FP, days 7-8) phases of their menstrual cycles. Phases were confirmed by estradiol and progesterone concentrations. Each EE test was preceded by ...
Broberg S - - 1989
Eight healthy men cycled at a work load corresponding to approximately 70% of maximal O2 uptake (VO2max) to fatigue (exercise I). Exercise to fatigue at the same work load was repeated after 75 min of rest (exercise II). Exercise duration averaged 65 and 21 min for exercise I and II, ...
Hutber C A - - 1989
We hypothesized that glycogenesis increases in muscle during exercise before significant glycogen depletion occurs. Therefore, rats ran for 15 or 90 min at speeds of 8-22 m/min. D-[5-3H]glucose (10 microCi/100 g body wt) was administered 10 min before the end of exercise. Hindlimb muscles [soleus (SOL), plantaris (PL), extensor digitorum ...
Kamp G - - 1989
1) Glycogen is degraded in the abdominal muscle of the shrimp Crangon crangon (Decapoda, Crustacea) during the recovery period following work. The regulation of post-exercise glycogen breakdown and the properties of glycogen phosphorylase (EC 2.4.1.1) have been studied: 2) Glycogen phosphorylase exists as unphosphorylated b-form and phosphorylated a-form, the latter ...
Ratz S R - - 1989
The effects of dietary manipulation (low- or high-carbohydrate) on performance of a short-duration exercise were studied with endurance- and intermittent-trained athletes. Eight subjects performed a depletion drill of 10 one minute workbouts at 7 W/kg and 85 rpm on a cycle ergometer. The subjects followed a dietary regimen of three ...
Kuipers H - - 1989
Since it has been demonstrated that endurance-trained cyclists are able to synthesize glycogen during mild exercise, glycogen synthesis was investigated in non-endurance-trained males and females as well. Seven males and nine females exercised on a cycle ergometer to deplete muscle glycogen. After the exhaustive exercise and taking a muscle biopsy, ...
Lavoie J M - - 1989
The metabolic effects of a selective hepatic vagotomy (HV) were investigated at rest and immediately after a 50-min exercise period (26 m/min, 0% grade) in rats subjected to an overnight 50% food restriction. This dietary restriction reduced liver glycogen content to 50% of normal resting concentrations (2.2-2.8 g/100 g). No ...
Sahlin K - - 1989
Eight men exercised at 66% of their maximal isometric force to fatigue after prior decrease in the glycogen store in one leg (low-glycogen, LG). The exercise was repeated with the contralateral leg (control) at the same relative intensity and for the same duration. Muscle (quadriceps femoris) glycogen content decreased in ...
Fridén J - - 1989
The fine structural pattern of glycogen storage in resting and sprint-exercised human vastus lateralis muscle fibres of different types was analysed using ultrahistochemical methods. Three male subjects (31-36 years) performed 60 consecutive, supramaximal bouts of bicycle exercise, each starting every 1 min and having a duration of 8 s (including ...
Trudeau F - - 1989
The respective roles of allosteric regulators and catecholamines in the control of muscle glycogen breakdown during exercise remain a matter of controversy. This study was designed to reassess the role of the sympathoadrenal system during prolonged exercise in rats. Animals were studied at rest or after treadmill exercise (28 m.min-1; ...
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