Previous studies showed that erythropoietin not only increases erythrocyte production but is also essential in both the synthesis and the good functioning of several erythrocyte membrane proteins, including band 3. It is still unknown whether anion and/or H(+) fluxes are modified by erythropoietin. This study aimed to evaluate the effect ...

The aims of this study were: (1) to identify the exercise intensity that corresponds to the maximal lactate steady state in adolescent endurance-trained runners; (2) to identify any differences between the sexes; and (3) to compare the maximal lactate steady state with commonly cited fixed blood lactate reference parameters. Sixteen ...

OBJECTIVES: To compare the predictive value of pH, base deficit and lactate for the occurrence of moderate-to-severe hypoxic ischaemic encephalopathy (HIE) and systemic complications of asphyxia in term infants with intrapartum asphyxia. STUDY DESIGN: We retrospectively reviewed the records of 61 full-term neonates (> or =37 weeks gestation) suspected of ...

The purpose of this study was to investigate the validity of non-invasive lactate threshold estimation using ventilatory and pulmonary gas exchange indices under condition of acute hypoxia. Seven untrained males (21.4+/-1.2 years) performed two incremental exercise tests using an electromagnetically braked cycle ergometer: one breathing room air and other breathing ...

Endurance training aiming at eliciting further increase of physical performance of competitive athletes demands serious time and intensity constraints. In addition, very high intensity training could lead to "over-loading" frequently associated with increased concentration of plasma lactate after maximum intensity exercise and proteinuria. We hypothesized that a newly available complex ...

Evaluations of biochemical changes associated with spring-style sled dog racing indicate that differences in cortisol, lactate, and serum glucose levels suggest exercise of moderate duration (but high intensity) has metabolic demands that dif-fer from those for typical endurance sled dog racing. Additionally, hematocrit, albumin, sodium, chloride, and blood urea nitrogen ...

No previous exercise studies in women have assessed the effects of the normal menstrual cycle on the lactate threshold (LT) measured during a graded, maximal exercise test. This is relevant to our understanding of exercise training and metabolism in eumenorrheic women. The present study, therefore, examined the effect of menstrual ...

PURPOSE: To test the hypothesis that prior heavy exercise increases the time to exhaustion during subsequent perimaximal exercise. METHODS: Seven healthy males (mean +/- SD 27 +/- 3 yr; 78.4 +/- 0.7 kg) completed square-wave transitions from unloaded cycling to work rates equivalent to 100, 110, and 120% of the ...

During the last two decades the concept of the MLSS (maximal lactate steady state) has been established. The MLSS detects the highest level of the BLC (blood lactate concentration) and the corresponding workload (MLSS workload) that can be maintained over time without continual BLC accumulation. In spite of a lack ...

AIM: The objective of this study was to verify the effects of active (AR) and passive recovery (PR) after a judo match on blood lactate removal and on performance in an anaerobic intermittent task (4 bouts of upper body Wingate tests with 3-min interval between bouts; 4WT). METHODS: The sample ...

The aim of this study was to evaluate the usefulness of a modification of the bicycle ergometer test, the subanaerobic threshold exercise test (SATET), as a screening test for patients with mitochondrial myopathies. Since the original SATET is frequently found to be strenuous for weak patients, a new variable (relative ...

During maximal exercise lactate taken up by the human brain contributes to reduce the cerebral metabolic ratio, O(2)/(glucose + 1/2 lactate), but it is not known whether the lactate is metabolized or if it accumulates in a distribution volume. In one experiment the cerebral arterio-venous differences (AV) for O(2), glucose ...

Sweat lactate indirectly reflects eccrine gland metabolism. However the potential influence of aerobic fitness on sweat lactate is not well-understood. Six males with high aerobic fitness [peak oxygen consumption ( VO(2)peak): 61.6 (2.5) ml.kg(-1).min(-1)] and seven males with low aerobic fitness [ VO(2)peak: 41.8 (6.4) ml.kg(-1).min(-1)] completed a maximal exertion ...

OBJECTIVE: Handbiking and wheelchair racing have gained increased popularity in Germany. This is important because of the inability of wheelchair-dependent people to maintain cardiovascular health and fitness through daily activities. The purpose of this study was to evaluate the energy expenditure (EE; kcal/h) of wheelchair-dependent individuals. METHODS: Ten wheelchair racers ...

Transitions between rest and work, in either direction, and heavy exercise loads are characterized by changes of muscle pH depending on the buffer power and capacity of the tissues and on the metabolic processes involved. Among the latter, in chronological sequence: (1). aerobic glycolysis generates sizeable amounts of lactate and ...

AIM: Lactate minimum test (LMT) has become popular in running evaluation. This study analysed the influence of different stage lengths and determination methods on lactate minimum swimming speed (LMS) and its validity for maximal lactate steady-state speed (MLSS-S) assessment. METHODS: Twelve male swimmers (19.7+/-1.6 years, 70.3+/-8.7 kg, 181.4+/-7.9 cm) randomly ...

Objectives were to develop a system to administer exercise training to dairy cows, to measure potential physiological indicators of fitness, and to assess physical fitness. Nonlactating, nonpregnant multiparous Holstein cows (n = 19) were in one of three exercise training treatments: no exercise; 1-h exercise; or 2-h exercise by walking ...

Increasing evidence indicates that mitochondrial dysfunction occurs in the central nervous system as well as in the peripheral tissues from Alzheimer's disease (AD) patients. We have recently shown that mitochondrial cytochrome c oxidase (COX) activity is significantly reduced in brain and platelets from AD patients compared to controls. In the ...

BACKGROUND: The chronic intake of alcohol affects the function of skeletal muscles. To elucidate the influence of acute alcoholic load on muscular metabolism during exercise, we analyzed expired gases to measure the volume of consumed oxygen and the volume of exhaled CO2. METHODS: Healthy volunteers were enrolled for the study. ...

OBJECTIVE: We have investigated the role of cardiopulmonary bypass on lactate metabolism in patients undergoing uncomplicated surgery for elective coronary artery bypass grafting (CABG). DESIGN: Prospective non-randomized observational study. SETTINGS: National Cardiovascular Center. PATIENTS. Three independent groups were studied: preoperative ( n=20), postoperative with bypass (CPB, n=20) and postoperative without ...

BACKGROUND: Adenosine A2a receptor stimulation can increase coronary perfusion and also reduce leukocyte-mediated inflammatory responses in some conditions. Hextend is a novel colloid solution that may have antioxidant properties. All these actions might be beneficial after severe chest trauma, but have never been investigated. To fill these gaps, this study ...

This study examined the effects of an amino acid mixture supplement on physiological response and ratings of perceived exertion during submaximal cycle-ergometer exercise in 15 healthy, untrained male students. Subjects performed submaximal sustained exercise (oxygen uptake at anaerobic threshold: 54.6 +/- 12.5% of maximum oxygen uptake capacity) with a cycle-ergometer ...

The effect of oral creatine supplementation on aerobic and anaerobic performance was investigated in 16 elite male rowers during 7-day endurance training. Before and after the daily ingestion of 20 g creatine monohydrate for 5 days (Cr-Group, n=8) or placebo (Pl-Group, n=8), subjects performed two exercise tests on a rowing ...

OBJECTIVE: To evaluate the effect of high-volume hemofiltration (HVHF) with lactate-buffered replacement fluids on acid-base balance. DESIGN: Randomized crossover study. SETTING: Intensive Care Unit of Tertiary Medical Center PARTICIPANTS: Ten patients with septic shock and acute renal failure. INTERVENTIONS: Random allocation to 8 h of isovolemic high-volume hemofiltration (ultrafiltration rate: ...

The cardio-pulmonary and biochemical changes observed in a case of McArdle's disease, exercising with increasing work rates to exhaustion in the "second-wind" phase of exercise are reported for the first time. A work rate of 275-325 watts was achieved. Venous blood lactate remained unchanged throughout. The plasma ammonium level reached ...

OBJECTIVE: The purpose of the study was to measure the effects of increased inspired oxygen on patients suffering severe head injury and consequent influences on the correlations between CPP and brain tissue oxygen (PtiO2) and the effects on brain microdialysate glucose and lactate. METHODS: In a prospective, observational study 20 ...

Prepartum intramammary antibiotic infusion of heifer mammary glands at 7 or 14 d before expected parturition is an effective procedure for eliminating many infections in heifers during late gestation and for reducing the prevalence of mastitis in heifers during early lactation and throughout lactation. Mastitis pathogens were isolated from 76% ...

The anaerobic threshold (AnT) is defined as the highest sustained intensity of exercise for which measurement of oxygen uptake can account for the entire energy requirement. At the AnT, the rate at which lactate appears in the blood will be equal to the rate of its disappearance. Although inadequate oxygen ...

With the expanding use of portable heart rate (HR) monitors in endurance sports, HR is increasingly used as a marker for exercise intensity. Hereby, HR at the so-called individual anaerobic threshold (IAT) is one possible reference point. However, once determined, it is often attempted to apply HR recommendations from one ...

Lower limb muscle chronic hyperactivity in hereditary spastic paraplegia (HSP) is the consequence of motor corticospinal tract involvement, which in turn has been hypothesized to be of mitochondrial origin. In order to assess skeletal muscle aerobic metabolism and sympathetic response during exercise in 10 HSP patients, we evaluated their blood ...

Characteristically, children recover faster than adults from various types of exercise. The purpose of the present study was to explain the children's faster recovery, in part, by addressing lactate (La) removal and comparing La disappearance dynamics in the two age groups following exercise of both similar and dissimilar peak blood-lactate ...

BACKGROUND: This paper presents a further analysis of biochemical data collected during a 1 year prospective study of 106 cases of heat exhaustion at a deep underground metalliferous mine. RESULTS: Multiple regression analysis results indicate that the haemoglobin, serum creatinine and plasma lactate concentrations are statistically significant predictors of the ...

Maximal exercise reduces the cerebral metabolic ratio (O2/(glucose + 1/2 lactate)) to < 4 from a resting value close to 6, and only part of this decrease is explained by the 'intent' to exercise. This study evaluated whether sensory stimulation of brain by muscle ischaemia would reduce the cerebral metabolic ...

We studied the role of lactate in gluconeogenesis (GNG) during exercise in untrained fasting humans. During the final hour of a 4-h cycle exercise at 33-34% maximal O(2) uptake, seven subjects received, in random order, either a sodium lactate infusion (60 micromol x kg(-1) x min(-1)) or an isomolar sodium ...

The purpose of this study was to investigate whether track running specialisation could be associated with differences in the ability to exchange and remove lactate. Thirty-four male high-level runners were divided into two groups according to their specialty (100 - 400 m/800 - 1500 m). All performed a 1-min 25.2 ...

Metabolic interventions improve performance during demand-induced ischemia by reducing myocardial lactate production and improving regional systolic function. We tested the hypotheses that 1) stimulation of glycolysis would increase lactate production and improve ventricular wall motion, and 2) the addition of fatty acid oxidation inhibition would reduce lactate production and further ...

Using triploidy as an experimental model, we examined whether cell size limits the post-exercise recovery process in fish. Because triploids generally possess larger cells, which could affect many physiological and biochemical processes, we hypothesized that triploids would take longer to recover from exhaustive exercise compared to diploids. To test this, ...

The maximal lactate steady state (MLSS) is defined as the highest blood lactate concentration (MLSSc) and work load (MLSSw) that can be maintained over time without a continual blood lactate accumulation. A close relationship between endurance sport performance and MLSSw has been reported and the average velocity over a marathon ...

To test whether the oral contraceptive pill cycle affects endocrine and metabolic responses to hypoxic (fraction of inspired oxygen = 13%, P(IO2): 95 mmHg; H) versus normoxic (P(IO2):153 mmHg; N) exercise, we examined eight women (28 +/- 1.2 yr) during the third (PILL) and placebo (PLA) weeks of their monthly ...

During standard graded exercise, blood lactate and blood ammonia levels increase in parallel and the two thresholds appear at the same relative intensity. The first part of this study aimed at comparing ammonia threshold to lactate threshold with five different graded exercise protocols. A significant difference between the two thresholds ...

BACKGROUND: The importance of lactate threshold (LT) as a determinant of performance in endurance sports has been established. In addition, it has been shown that during running and selected other endurance competitions, athletes perform at a velocity and VO2 slightly above LT for the duration of the event. Prior work ...

PURPOSE: This study investigated whether active warm-up (AW) would increase muscle acetylcarnitine concentration before exercise, thereby reducing the reliance on nonoxidative ATP production during subsequent high-intensity exercise. METHODS: Six female subjects performed a 30-s sprint at 120% of their maximal power output on an electronically braked cycle ergometer 5 min ...

To test the hypothesis that lactate plays a central role in the distribution of carbohydrate (CHO) potential energy for oxidation and glucose production (GP), we performed a lactate clamp (LC) procedure during rest and moderate intensity exercise. Blood [lactate] was clamped at approximately 4 mM by exogenous lactate infusion. Subjects ...

The break point of the curve of blood lactate vs exercise load has been called anaerobic threshold (AT) and is considered to be an important indicator of endurance exercise capacity in human subjects. There are few studies of AT determination in animals. We describe a protocol for AT determination by ...

PURPOSE: The aim of the study was to examine the effects of different lactate elevation protocols on the determination of the lactate minimum (Lac(min)) point. METHODS: Eight highly trained racing cyclists each completed four continuous ramp lactate minimum tests using the following blood lactate elevation protocols: 1) continuous ramp maximal ...

OBJECTIVE: To test the possible antipanic effects of acute exercise in healthy volunteers exposed to an inhalation of 35% CO2 challenge. METHOD: Twenty healthy subjects in a randomized separate group design, performed exercise in a bicycle ergometer reaching >6 mm of blood lactate and a control condition of minimal activity ...

It is assumed that the maximal lactate steady state (MLSS) can be used to establish the highest workload that can be maintained over time without continual blood lactate accumulation. In untrained subjects, and in both elite and junior athletes, MLSS occurs at different blood lactate concentrations (BLC) for different exercise ...

Calcitonin gene-related peptide (CGRP) and adrenomedullin (AM) are potent vasorelaxant peptides. This study examined exercise-induced changes in CGRP and AM levels in 12 healthy sea level natives at sea level (SL) and subsequently after 24 h (HA1) and 5 days (HA5) in high altitude hypoxia (4559 m). Plasma values of ...

The purpose of this study was to examine the effects of respiratory alkalosis on human skeletal muscle metabolism at rest and during submaximal exercise. Subjects exercised on two occasions for 15 min at 55 % of their maximal oxygen uptake while either hyperventilating (R-Alk) or breathing normally (Con). Muscle biopsies ...

Consecutive 60-min microdialysis samples were taken from the tibial anterior muscle in 11 healthy subjects and 4 patients with mitochondrial myopathy before (2-3 samples) and after (3-4 samples, 2 controls and 1 patient excluded) sustained isometric foot dorsiflexions. Before exercise, mean concentrations of lactate, pyruvate, hypoxanthine, urate, aspartate, and glutamate ...