Search Results
Results 801 - 850 of 1394
< 12 13 14 15 16 17 18 19 20 21 22 >
Oosthuyse T - - 1999
PURPOSE: An athlete's ability to repeatedly perform at high intensities during intermittent exercise could be related to an accelerated plasma lactate removal ability during recovery periods. METHODS: We determined the decline in plasma lactate levels during passive recovery after an incremental exercise test to exhaustion on a bicycle ergometer in ...
Branco L G - - 1999
Hypoxia induces a regulated decrease in body temperature (Tb; anapyrexia) in organisms ranging from protozoans to mammals, but very little is known about the mechanisms involved. Several candidates have been suggested to mediate hypoxia-induced anapyrexia, among them lactate, which is a classical compansion of hypoxic stress in vertebrates. The present ...
Baum K - - 1999
PURPOSE: Roller skiing is frequently used in Nordic disciplines during the off-season periods. Recently, in-line skating has become a potential alternative. In the present study, the responses of heart rate, oxygen uptake, respiratory exchange ratio, and lactic acid concentration to roller skiing and in-line skating were compared in competitive biathletes. ...
Sladen R N - - 1999
Physiologic hyperlactatemia must be distinguished from lactate acidosis (lactate > 5 mM/L, pH < 7.32). Sustained lactic acidosis, or changes in lactate in response to inotropic support, are useful predictors of mortality in severe sepsis and trauma, and superior to hemodynamic markers such as DO2 and VO2. Base deficit is ...
Kinugawa T - - 1999
Plasma levels of ammonia and hypoxanthine (HX) can be indices of purine nucleotide degradation. The present study determined if patients with heart failure (HF) have altered exercise plasma ammonia and HX levels relative to the peak work rate performed. Blood lactate, plasma ammonia, and plasma HX levels were measured in ...
Fukuba Y - - 1999
The aim of this study was to measure serial changes in the rate of blood lactate clearance (gamma2) in response to sequential periods of training and detraining in four male triathletes aged 22-44 years. There were two major phases of training and taper, each lasting 4-5 weeks (training 1 = ...
Weston A R - - 1999
Nine African and eight Caucasian 10-km runners resident at sea level volunteered. Maximal O2 consumption and peak treadmill velocity (PTV) were measured by using a progressive test, and fatigue resistance [time to fatigue (TTF)] was measured by using a newly developed high-intensity running test: 5 min at 72, 80, and ...
Beaufort-Krol G C - - 1999
In a previous study [G. C. M. Beaufort-Krol, J. Takens, M. C. Molenkamp, G. B. Smid, J. J. Meuzelaar, W. G. Zijlstra, and J. R. G. Kuipers. Am. J. Physiol. 275 (Heart Circ. Physiol. 44): H1503-H1512, 1998], a lower systemic O2 supply was found in lambs with aortopulmonary left-to-right shunts. ...
Ament W - - 1999
The aim of this study was to investigate whether the increase of ammonia concentration and lactate concentration in blood was accompanied by an increased expiration of ammonia during graded exercise. Eleven healthy subjects performed an incremental cycle ergometer test. Blood ammonia, blood lactate and the amount of expired ammonia were ...
Guével A - - 1999
The rules of competitive boardsailing events were changed before the Atlanta Olympic Games. Pumping the sail (pulling repeatedly on the rig) is now allowed and the duration of races has been shortened. Eight members of the French national team (mean age 23+/-2.7 years) participated in this study. Their cardiac and ...
Bernard SF - - 1999
Continuous infusions of 2-[3H]glycerol and 1-[14C]palmitate were performed in vivo in rainbow trout to measure the effects of prolonged swimming on (1) the rate of appearance of glycerol (Ra glycerol or lipolytic rate), (2) the rate of appearance of non-esterified fatty acids (Ra NEFA) and (3) the rate of triacylglycerol:fatty ...
Petrides J S - - 1999
The role that metabolic products play in regulating the hypothalamic-pituitary-adrenal (HPA) axis during strenuous exercise is speculative. This investigation examined the extent to which lactic acid, a major metabolite of anaerobic exercise, directly affects hypothalamic-pituitary function. Specifically, beta-endorphin secretion was measured from AtT-20 (D-16) mouse corticotroph tumor cells treated either ...
Held T - - 1999
Capillary blood lactate assessment is increasingly used by well-trained runners to monitor the intensity of endurance exercise. In order to examine the known association of exercise intensity with blood lactate accumulation also in less trained subjects, we analysed data from a standardized incremental maximal test on the treadmill of 319 ...
Beaufort-Krol G C - - 1998
Free fatty acids are the major fuels for the myocardium, but during a higher load carbohydrates are preferred. Previously, we demonstrated that myocardial net lactate uptake was higher in lambs with aortopulmonary shunts than in control lambs. To determine whether this was caused by an increased lactate uptake and oxidation ...
Ellmerer M - - 1998
The present study was carried out to investigate in vivo in healthy humans the method of open-flow microperfusion for monitoring of the subcutaneous (s.c.) lactate concentration during rest and cycle ergometer exercise. Using open-flow microperfusion, a perforated double lumen catheter with an inflow and an outflow connection is inserted into ...
Brooks G A - - 1998
We evaluated the hypotheses that on acute exposure to hypobaric hypoxia, sympathetic stimulation leads to augmented muscle lactate production and circulating [lactate] through a beta-adrenergic mechanism and that beta-adrenergic adaptation to chronic hypoxia is responsible for the blunted exercise lactate response after acclimatization to altitude. Five control and 6 beta-blocked ...
Vanuxem D - - 1998
This study, intended to evaluate the role of ammonia (NH3) as a ventilatory stimulus, was conducted in three groups of subjects: 14 sedentary individuals, 12 triathletes, 5 patients with a glycolytic deficiency (Mc Ardle disease). All subjects performed maximal exercise tests on a cycle ergometer. Ventilation measured at maximal oxygen ...
Corbett R - - 1998
Numerous studies using adult animal models suggest that dichloroacetate (DCA) may have neuroprotective properties by virtue of its ability to increase rates of metabolism and, therefore, clearance of brain lactic acidosis, which may accumulate during cerebral ischemia. We tested the hypothesis that postischemic DCA administration affects lactate and acid clearance ...
Schuler P B - - 1998
BACKGROUND: The purpose of this study was to measure the amount of lactate produced, as an indication of fatigue, in response to maximal and submaximal stairstepper (SM) and treadmill (TM) exercise. METHODS: Thirty volunteers (15 males, mean age 23 yrs; 15 females, mean age 22 yrs) completed maximal and submaximal ...
ChwalbiƄska-Moneta J - - 1998
The aim of this study was to follow up the electromyographic activity (EMG) of dynamically working muscles with simultaneous determinations of blood lactate and plasma catecholamine concentrations during progressive exercise. Twenty eight male soccer players aged 20.6 +/- 0.8 yrs performed incremental bicycle ergometer exercise test. The test consisted of ...
Mechau D - - 1998
This study was designed to measure the electroencephalogram (EEG) after exercise with increasing intensity. In a field test with increments in running velocity a 2-min EEG was recorded, together with blood lactate concentration and heart rate, after each stage. An individual protocol was used, with up to six stages of ...
Fly A D - - 1998
Fourteen healthy, lactating women (aged 25-38 y and between 2 and 8 mo postpartum) participated in both a maximal graded exercise test and a 30-min rest period to determine the influence of exercise on the concentration of selected milk minerals and electrolytes. Treatment order was randomized and treatments were conducted ...
Schmid A - - 1998
The deflection point (DP) of the heart rate in relation to the work rate (WR) of 8 male endurance-trained paraplegics and 11 male physically active sports students was investigated during nonsteady-state incremental arm cranking ergometry (IT) and compared to the 4 mmol x l(-1) blood lactate concentration threshold and to ...
Martinsen E W - - 1998
We wanted to test the tolerance of intensive exercise and corresponding high levels of lactate in patients with panic disorder. Thirty-five consecutive patients with DSM-III-R panic disorder completed submaximal tests, and 24 completed additional supramaximal exercise tests. All experienced high values of lactate during the supramaximal test (M = 10.7 ...
Chicharro J L - - 1998
Little attention has been directed toward identifying the changes which occur in salivary composition in response to exercise. To address this, our article first refers to the main aspects of salivary gland physiology. A knowledge of the neural control of salivary secretion is especially important for the understanding of the ...
Spangenburg E E - - 1998
Numerous studies suggest that the accumulation of lactate during exercise contributes to the fatigue process. This notion is based on close negative correlations between force and intracellular muscle lactate concentrations during fatigue and recovery. In this investigation, we attempted to determine if lactate directly affects muscle force output. This was ...
Stallknecht B - - 1998
Lactate accumulates if pyruvate formation exceeds pyruvate oxidation. Accelerated glycogenolysis is essential for lactate production. Glycogen and epinephrine enhance glycogen phosphorylase activity and this is higher in type II b than in type I fibers. Pyruvate oxidation is enhanced by exercise-induced increase in pyruvate dehydrogenase activity and is relatively impaired ...
Jenkins B G - - 1998
Huntington's disease (HD) is the result of an expanded (CAG) repeat in a gene on chromosome 4. A consequence of the gene defect may be progressive impairment of energy metabolism. We previously showed increased occipital cortex lactate in HD using localized 1H spectroscopy. We have now extended these studies to ...
Ye J M - - 1998
Skeletal muscle can release or take up lactate depending on the lactate concentration gradient across the cell membrane. In the perfused rat hindlimb without arterial lactate, both noradrenaline (NA) infusion and increased flow promote lactate release and oxygen consumption (VO2). However, it is unclear whether NA or increased flow rate ...
Brooks G A - - 1998
The 'crossover' and 'lactate shuttle' concepts of substrate utilization in humans during exercise are extended to describe metabolic responses on other mammalian species. The 'crossover concept' is that lipid plays a predominant role in sustaining efforts requiring half or less aerobic capacity (VO2max); however, greater relative efforts depend increasingly on ...
Mendelowitsch A - - 1998
OBJECTIVES: Critical vascular surgery of the brain or the heart occasionally requires total cessation of the circulatory system. Profound hypothermia is used to protect the brain from ischaemic injury. This study explores the use of microdialysis to measure metabolic indices of ischaemia: glutamate, lactate, and pH, and cerebral temperature during ...
Konstantaki M - - 1998
The aim of this study was to explore the relationship between physiological responses to dry-land testing and to water polo playing. Eight female water polo players (mean+/-s: age 26.7+/-5.7 years, height 169+/-6 cm, body mass 65.3+/-7.0 kg) participated in two assessments. The first involved a discontinuous incremental arm test to ...
Osterode W - - 1998
To assess whether hormone and metabolic responses in an upright bicycle exercise test are equivalent for subjects with different physical characteristics if test duration for reaching individual maximal work capacity (PWCmax) is standardized we investigated plasma catecholamines, human atrial natriuretic peptide (hANP) and blood lactate responses in twenty healthy sedentary ...
Dassonville J - - 1998
BACKGROUND: The purpose of the study was to compare blood lactate concentrations determined in blood sampled from three sites (finger capillary, ear-lobe capillary, and forearm vein) during exercise on three different ergometers (a cycle ergometer, a treadmill and an arm-crank ergometer). METHODS: A total of 312 well-trained subjects performed either ...
Nikolaizik W H - - 1998
Physical exercise can improve sputum clearance in patients with cystic fibrosis (CF). To set up individual training protocols it is desirable to know the anaerobic threshold (AT). Established methods such as blood lactate measurements and ergometry can only be performed in specialized centers. Conconi showed that the heart rate threshold ...
Lane R J - - 1998
OBJECTIVES: To examine the proportions of type 1 and type 2 muscle fibres and the degree of muscle fibre atrophy and hypertrophy in patients with chronic fatigue syndrome in relation to lactate responses to exercise, and to determine to what extent any abnormalities found might be due to inactivity. METHODS: ...
Baker S K - - 1998
We investigated the effects of 3 wk of moderate- (21 m/min, 8% grade) and highintensity treadmill training (31 m/min, 15% grade) on 1) monocarboxylate transporter 1 (MCT-1) content in rat hindlimb muscles and the heart and 2) lactate uptake in isolated soleus (Sol) muscles and perfused hearts. In the moderately ...
Urhausen A - - 1998
In the present prospective longitudinal study 17 male endurance trained athletes (cyclists and triathletes; age 23.4+/-6.7 years, VO2max 61.2+/-7.5 ml x min(-1) x kg(-1); means+/-SD) were investigated both during a state of overtraining syndrome (OT: N=15), mainly induced by an increase of exercise intensity, as well as several times in ...
Hardarson T - - 1998
The purpose of this study was to examine the effects of raising the arterial La- and K+ levels on minute ventilation (VE) in rats. Either La- or KCl solutions were infused in anesthetized spontaneously breathing Wistar rats to raise the respective ion arterial concentration ([La-] and [K+]) gradually to levels ...
Chmura J - - 1998
Previous investigations from this laboratory have demonstrated that during graded exercise with exercise intensities increasing every 3 min until exhaustion the multiple choice reaction time (RT) decreased until the intensity exceeded the lactate threshold (LT) by approximately 25%, and then rapidly increased. The aim of this study was to follow ...
Martin N A - - 1998
OBJECTIVE: To determine the comparative effect of sports massage, active recovery, and rest on promoting blood lactate clearance after maximal anaerobic (supramaximal) leg exercise. DESIGN AND SETTING: A counterbalanced experimental design with repeated measures was used. The repeated measures were the three treatment conditions. The order of the conditions was ...
Söderholm J D - - 1998
The Ussing chamber is increasingly being used for in vitro studies of human intestinal mucosa, but little attention has been paid to the viability of specimens over time. Ninety-one mucosal specimens from the ileum in 19 patients operated on for colonic cancer were studied in regard to intestinal barrier function, ...
McKeever K H - - 1998
The purpose of this experiment was to test the hypothesis that chronic (89 days) administration of recombinant equine somatotropin (eST) would increase aerobic capacity and improve exercise performance in old mares. Fifteen, healthy, unfit, aged (20-26 year old) mares were randomly assigned to a treatment (eST, 12.5 mg day-1 in ...
Szmedra L - - 1998
We examined the effects of listening to headphone music in ten well trained men (25.1 +/- 6 years) during treadmill running. Maximal oxygen consumption, determined by open circuit spirometry, was followed by two submaximal work bouts 72 hours apart. The work bouts consisted of a supine rest, a 15 minute ...
Bonen A - - 1998
We examined the effects of increasing a known lactate transporter protein, monocarboxylate transporter 1 (MCT1), on lactate extrusion from human skeletal muscle during exercise. Before and after short-term bicycle ergometry training [2 h/day, 7 days at 65% maximal oxygen consumption (VO2max)], subjects (n = 7) completed a continuous bicycle ergometer ...
Desagher S - - 1997
Hydrogen peroxide (H2O2) is suspected to be involved in numerous brain pathologies such as neurodegenerative diseases or in acute injury such as ischemia or trauma. In this study, we examined the ability of pyruvate to improve the survival of cultured striatal neurons exposed for 30 min to H2O2, as estimated ...
Vukovich M D - - 1997
The purpose of this study was to determine if amino acid supplementation influences blood and muscle lactate response to exercise and the time course of the metabolic adaptations to training. Two groups of untrained males (n = 7 each) were given (double-blind) a daily supplement (2.9 g.day-1) containing a mixture ...
Bangsbo J - - 1997
1. Transport of lactate, H+ and fluid across muscle sarcolemma was studied in contracting muscles under varying blood acid-base conditions. 2. Subjects performed two-legged submaximal knee-extensor exercise for 29-35 min consisting of warming up for 5 min followed by 10 min of leg exercise (L1), leg and arm exercise for ...
Mognoni P - - 1997
The average maximal peak torques of the knee extensor and knee flexor muscles were measured during one, two or three series of 20 maximal contractions at an angular velocity of pi rad s(-1). Each series lasted about 20 s. After the first series, a 10 min rest was allowed before ...
Monzani F - - 1997
Alterations in muscle structure and function have been reported in overt hypothyroidism, with decreased activity of enzymes involved in anaerobic and oxidative glucose metabolism. To test whether similar changes in muscle energy metabolism are present in subclinical hypothyroidism (sHT), we studied 12 patients with sHT who complained of mild neuromuscular ...
< 12 13 14 15 16 17 18 19 20 21 22 >