PURPOSE: The purpose of this study was to examine the effect of dynamic resistance exercise on the response patterns of adrenal medullary neurohormones in strength-trained men. METHODS: Ten strength-trained men (21.7+/-0.58 yr) gave informed consent and performed two resistance exercise protocols, high force and high power, of equal total work ...

OBJECTIVE: In the present study we investigated whether plasma catecholamine (CA) responses to short-term severe exercise (SX) are affected by different training regimen and whether this test will increase plasma catecholamine sulfates. METHODS: Nine anaerobically (ANTA) and eight aerobically trained male athletes (ATA) performed a severe treadmill exercise test (SX) ...

PURPOSE: In the fasted state the lipid fuels for muscle metabolism are free fatty acids (FFA) released either from intramuscular triglycerides (TG), plasma albumin, or TG in circulating very low density lipoproteins (VLDL). The purposes of this study were to determine the influence of acute exercise of moderate intensity on ...

OBJECTIVES: The purpose of this study was to determine whether patients with syndrome X have altered potassium metabolism. BACKGROUND: Patients with syndrome X have angina pectoris and exercise induced ST segment depression on the electrocardiogram despite normal coronary angiograms. Increasing evidence suggests that myocardial ischemia is uncommon in these patients. ...

To test the hypothesis that exercise-induced hypervolemia is a posture-dependent process, we measured plasma volume, plasma albumin content, and renal function in seven healthy subjects for 22 h after single upright (Up) or supine (Sup) intense (85% peak oxygen consumption rate) exercise. This posture was maintained for 5 h after ...

The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) has been shown to modulate various physiological and psychological functions such as fatigue. Altered regulation of the serotonergic system has been suggested to play a role in response to exercise stress. In the present study, the influence was investigated of acute endurance exercise and short-term ...

PURPOSE: In two separate but identical studies, the effect of vitamin B-6 supplementation was examined on plasma energy substrates, catecholamines, and 13 amino acid concentrations during exercise. METHODS: Eleven trained men performed two separate exhaustive exercise tests at 71.0+/-4.6% VO2max during two separate 9-d controlled diet periods. Exercise test 1 ...

The aim of the present study was to compare the effects of exercise at 80% VO2max (resulting in fatigue within 1 h) with more prolonged exercise at a lower work rate (55% VO2max for up to 3 h) on blood neutrophil function and plasma concentrations of cortisol, glutamine and glucose. ...

The sulphonated amino acid taurine increased significantly in the plasma of trained athletes after three endurance exercises of different duration and intensity, a 90 min run on a treadmill at 75% of an individual's VO2 peak, a Marathon, 42.2 km and a 100 km run, by 19%, 77% and 36%, ...

To examine whether endotoxaemia accompanying long-term, strenuous physical exercise is involved in exercise-induced increase in plasma tumour necrosis factor alpha (TNF-alpha) concentration and polymorphonuclear neutrophil (PMN) activation, 14 male recreational athletes [mean age 28 (SEM 1) years] were studied. Exercise consisted of a 1.5-km river swim, a 40-km bicycle race, ...

We tested the hypothesis that measurement of plasma catecholamine sulphate concentration after exercise reflects the overall activation of the sympathoadrenergic system during the whole period of repeated bouts of short-term exercise. A group of 11 male athletes performed two exercise tests at similar average power outputs consisting of three sets ...

Gecarcoidea natalis is a land crab that migrates annually several kilometres to breed. The O2-binding properties of haemocyanin in G. natalis were investigated in vitro to test the idea that the O2-binding properties of the haemocyanin of land crabs are not dependent on circulating modulators and to provide a model ...

A mathematical model of capillary oxygen transport was formulated to determine the effect of increasing plasma solubility, e.g., by the addition of an intravascular fluorocarbon emulsion. The effect of increased plasma solubility is studied for two distributions of fluorocarbon, when the fluorocarbon droplets are uniformly distributed throughout the plasma and ...

1. There is controversy regarding plasma catecholamine levels in patients with hypertrophic cardiomyopathy (HCM) and few data exist on serial plasma catecholamine measurements during exercise. The present study determined whether cardiovascular and plasma catecholamine responses to exercise were altered in patients with HCM. 2. Plasma noradrenaline (NA) and adrenaline were ...

OBJECTIVE: Increase in plasma hypoxanthine (HX) (purine nucleotide degradation product from working muscle) reflects insufficiency of adenosine triphosphate (ATP) supply during exercise, and the exercise-induced increase in plasma norepinephrine (NE) can be an index of sympathetic nerve activity. The aim of this study was to investigate the relationship between plasma ...

To determine whether oral branched-chain amino acids (BCAAs) improve exercise capacity, six fasting patients with McArdle's disease were given a solution of BCAA (77 mg/kg) or a control noncaloric beverage 30 minutes before exercise. The BCAA meal tripled plasma BCAA levels, increased BCAA catabolism as indicated by greater exercise increases ...

To test the hypothesis that the magnitude of reduction in plasma volume and work capacity following exposure to simulated microgravity is dependent on the initial level of aerobic fitness, peak oxygen uptake (VO2peak) was measured in a group of physically fit subjects and compared with VO2peak in a group of ...

The effects of exercise on the rheological properties of blood have not received much research attention. Recent, limited evidence indicates that the viscosities of whole blood and plasma increase in response to a variety of exercise protocols. The increase in whole blood viscosity is mainly attributed to an increase in ...

A case of severe hyponatraemia in a 56-year-old male alcohol misuser secondary to beer potomania is presented. In view of severe volume depletion and the patient's inability to drink, normal saline was cautiously infused. Despite initial improvement, he subsequently deteriorated neurologically. Magnetic resonance imaging demonstrated the classical lesion of central ...

BACKGROUND: The purpose for this study was to evaluate various carbohydrate (CHO)-electrolyte fluid formulations for consumption by astronauts to maintain or restore their plasma volume (PV) and total body water (TBW) during and after extravehicular activity (exercise experiment, EE) and for a few hours before reentry and immediately after landing ...

OBJECTIVE: To assess the clearance of radiolabeled tracer albumin (RISA) from peritoneal cavity to plasma (Cl-->P) in rats under essentially "normal" conditions, that is, when intraperitoneal hydrostatic pressure (IPP) is subatmospheric and the intraperitoneal (IP) "free" fluid volume (IPV) is low. METHODS: A volume of 0.3 mL of RISA was ...

Glutamine is the most abundant free amino acid in human muscle and plasma and is utilised at high rates by rapidly dividing cells, including leucocytes, to provide energy and optimal conditions for nucleotide biosynthesis. As such, it is considered to be essential for proper immune function. During various catabolic states ...

We wished to determine whether the increased ACTH during prolonged exercise was associated with changes in peripheral corticotropin-releasing hormone (CRH) and/or arginine vasopressin (AVP). Six male triathletes were studied during exercise: 1 h at 70% maximal oxygen consumption, followed by progressively increasing work rates until exhaustion. Data obtained during the ...

BACKGROUND: The aim this work was to study the effects of acute exercise on plasma homocysteine level. METHODS: Twenty healthy, physically active males aged 24-39 (X = 29) ran on treadmill at an intensity of 70% of their maximal heart for 30 minutes. Blood was taken before, immediately following and ...

A number of studies have demonstrated considerable plasma volume changes during and after exposure to different environmental and physiological conditions. These changes are thought to result from transient fluid shifts into (haemodilution) and out of (haemoconcentration) the intravascular space. If the levels of plasma constituents are to be routinely measured ...

The impact of posture on the immediate recovery of intravascular fluid and protein after intense exercise was determined in 14 volunteers. Forces which govern fluid and protein movement in muscle interstitial fluid pressure (PISF), interstitial colloid osmotic pressure (COPi), and plasma colloid osmotic pressure (COPp) were measured before and after ...

There is such a speculation that if the decrease in plasma volume (PV) makes central blood volume (CBV) and stroke volume (SV) reduce during prolonged BR, but if the changes in red cell volume (RCV) is little and a physiological salt water (PSW) volume matched to a body fluid loss ...

The effects of administering (1) 6L isotonic oral rehydration solution (ORS), similar in composition to plasma (except for an elevated potassium concentration) and with an osmotic skeleton and (2) 6L water (no osmotic skeleton), were evaluated in five thoroughbred horses following exercise-induced dehydration. The horses were exercised on a treadmill ...

Arterial plasma K+ and lactate concentrations ([K+]a and [lactate]a), as well as blood oxygenation status, were measured in relation to increasing swimming speeds in rainbow trout Oncorhynchus mykiss. Neither [K+]a nor [lactate]a changed at swimming speeds below 1.5 BL s-1, where BL is total body length. Between 1.5 and 2.0 ...

BACKGROUND: Plasma osmolality (Osm) is important for controlling and maintaining plasma volume (PV) and body water. The effect of oral rehydration fluids for ameliorating dehydration is well-established; but optimal composition and Osm of fluids for hyperhydrating normally hydrated subjects is less clear. METHODS: Six treatments were used without and with ...

Glutamine is an essential substrate for the proper functioning of cells of the immune system. Falls in plasma glutamine concentration after exercise may have deleterious consequences for immune cell function and render the individual more susceptible to infection. The purpose of the present study was to examine changes in plasma ...

PURPOSE: The purpose of this study was to investigate the relationship between training-induced alterations in plasma volume (PV) and changes in fluid and electrolyte regulatory hormones during prolonged exercise. METHODS: Seven male subjects (VO2peak 49.2 +/- 2.4 mL.kg-1.min-1, X +/- SE) performed a cycling test before (C) and after (T) ...

During both high-intensity and short-distance exercise, the high rate of expended energy is met by anaerobic oxidation of glucose to lactic acid; this is the main cause of metabolic acidosis observed during racing. In addition, plasma volume decreases because water moves from the vasculature to the intracellular and interstitial spaces ...

The plasma noradrenaline (NA) and adrenaline (A) concentration responses of seven young male athletes [15 (SD 1) years] and seven adult male athletes [25 (SD 6) years] were investigated together with the serum testosterone (Tes) concentration responses in four different half-squatting exercises. The loads, number of repetitions, exercise intensity and ...

The present study was carried out to elucidate whether an exercise-induced increase in plasma hydrogen ion concentration influences aldosterone secretion. Six healthy men (aged 22-25 years) performed two intermittent exercise tests with and without drug administration. The intensities of these exercise tests were 40% maximal oxygen uptake (VO2max) and 90% ...

Effects of a serotonin re-uptake inhibitor and oral amino acid supplementations on physical and mental performance as well as neuroendocrine variables were investigated. 10 male subjects cycled in four trials until exhaustion. Participants ingested a placebo in trial (T) I, 20 mg paroxetine in T II, 21 g branched-chain amino ...

This study examined the physiological effect of reduced plasma cortisol (C) during prolonged exercise in humans. The effects of normal C (NC) were compared with metyrapone-induced low C (LC) on plasma substrate availability and the respiratory exchange ratio during 2 h of exercise at approximately 60% peak O2 consumption in ...

The effect of chronic voluntary exercise on the plasma level of nitrate, a major stable metabolite of nitric oxide (NO) was studied in spontaneously hypertensive rats (SHR). Exercise consisted of spontaneous running in wheels for 3-35 days. Blood samples were collected after 3, 7, 14, 21 and 35 days of ...

Muscle glycogen and glucose have been suggested to be carbon-chain precursors for glutamine synthesis in skeletal muscle. Therefore, the aim of the present study is to investigate whether carbohydrate supplementation affects plasma glutamine and other amino acids during exercise and 7 h of recovery. Eight well-trained subjects cycled at an ...

The administration of 41 of an isotonic, plasma-like oral rehydration solution (ORS) with an osmotic skeleton and 41 of water (water; no osmotic skeleton), were evaluated in five thoroughbred horses. Solutions were administered by nasogastric tube 4 h after feeding. Uptake of deuterium, concentrations of plasma sodium, potassium, chloride, glucose, ...

Cardiovascular and neuroendocrine responses to exercise in a physically fit and an untrained group of young healthy subjects were compared to study the significance of physical fitness for performance in a discipline for which the athletes were not trained. Ten wrestlers of national rank prepared for an international competition (age ...

The cardiovascular and humoral responses to sustained muscle metaboreflex activation were examined in eight male volunteers while they performed two 24-min exercise protocols. Each of these consisted of six 1-min bouts of isometric handgrip exercise (the left and right hands being used alternately) at 50% of maximal voluntary contraction; after ...

We evaluated the hypothesis that impaired sarcolemmal function associated with exaggerated potassium release, impaired potassium uptake, or both may contribute to exertional fatigue and abnormal circulatory responses to exercise in McArdle disease (MD). The cellular mechanism of exertional fatigue and muscle injury in MD is unknown but likely involves impaired ...

To investigate the effects of chronic exercise and deconditioning on platelet function in women, 16 healthy sedentary women were divided into control and exercise groups. The exercise group cycled on an ergometer at 50% maximal oxygen consumption for 30 min/day, 5 days/wk, for two consecutive menstrual cycles and then were ...

BACKGROUND: Exercise increases plasma arginine-vasopressin (PAVP), plasma atrial natriuretic peptide (PANP), plasma renin activity (PRA), and plasma aldosterone (PALDO) in an intensity-dependent manner. With acute exercise, urine osmolality (UOSM) is often decreased despite increased PAVP. The hyperbaric environment lowers PAVP and UOSM, and increases urine flow. HYPOTHESIS: If work produced ...

To identify whether muscular exercise increases the plasma concentration of uridine and of purine bases, the effect of rigorous muscular exercise was determined in five healthy men with a bicycle ergometer. Twenty-five-minute muscular exercise at 65% maximum O2 consumption increased the concentration of uridine, purine bases, and inorganicphosphate in plasma ...

BACKGROUND: A laboratory-based model which links regional and central fatigue during physical exercise has not yet developed. Today we can assay the oxypurines, a specific and sensible marker of muscle cell-energy exhaustion during strenuous physical exercise, thus allowing us to insight in peripheral fatigue mechanisms. Prolonged physical exercise modifies plasma ...

This study employed Stewart's physicochemical approach to quantify the effects of pregnancy and strenuous exercise on the independent determinants of plasma H+ concentration ([H+]). Subjects were nine physically active pregnant women [mean gestational age = 33 +/- 1 (SE) wk] and 14 age-matched nonpregnant controls. Venous blood samples and respiratory ...

Loperamide, a peripherally acting opiate receptor agonist with antidiarrheal action, inhibits ileal and colonic motor function. It was determined whether loperamide also affects gallbladder emptying and pancreatic enzyme secretion in humans. Plasma cholecystokinin (radioimmunoassay), gallbladder volume (ultrasonography), and intraduodenal bilirubin and amylase output (spot sampling) were measured at regular intervals ...

Although transdermal nicotine patches have been studied extensively under recommended conditions, the present studies were designed to assess the nicotine plasma levels and the safety of transdermal nicotine patches in smokers undergoing situations suspected to result in increased nicotine plasma levels. The first study examined the effects of increasing nicotine ...