To study the role of muscle mass and muscle activity on lactate and energy kinetics during exercise, whole body and limb lactate, glucose, and fatty acid fluxes were determined in six elite cross-country skiers during roller-skiing for 40 min with the diagonal stride (Continuous Arm + Leg) followed by 10 ...

The lactate transport activity of red blood cells (RBC) varies widely among different species; in equine RBC, the activity of the main lactate carrier, H+-monocarboxylate co-transporter (MCT), is distributed bimodally. The influence of lactate transport activity is measurable in vivo; after maximal exercise, the RBC lactate concentration in horses with ...

The aim of this study was to investigate the heart rate and blood lactate responses to exercise in event horses in normal training, and to compare them to those encountered in eventing competition. It was hypothesised that the responses during exercise in the course of training for CCI*** events would ...

The general objective of this study was to evaluate a crude Ostertagia ostertagi antigen enzyme-linked immunosorbent assay (ELISA) for monitoring gastrointestinal parasites in lactating dairy cattle. A longitudinal study of gastrointestinal parasites in lactating dairy cows was carried out in 38 herds in four provinces of Canada (Prince Edward Island, ...

The aim of the present study was to investigate the relationships between lactate exchange and removal abilities and the capacity to prolong exercise, as assessed by the time to exhaustion (Tlim) at a work rate corresponding to VO(2)max (Pa max ). The individual blood lactate recovery curves obtained for 13 ...

To investigate the effect of L-arginine supplementation (L-ARG) on physiological and metabolic changes during exercise, we determined in a double-blind study the cardiorespiratory (heart rate, oxygen consumption (VO(2)) and carbon dioxide production (VCO(2)) and the metabolic (lactate and ammonia) responses to maximal exercise after either an intravenous L-ARG hydrochloride salt ...

Ischemic forearm exercise invariably causes muscle cramps and pain in patients with glycolytic defects. We investigated an alternative diagnostic exercise test that may be better tolerated. Nine patients with McArdle disease, one with the partial glycolytic defect phosphoglycerate mutase deficiency, and nine matched, healthy subjects performed the classic ischemic forearm ...

We hypothesized that reliance on lactate as a means of energy distribution is higher after a prolonged period of acclimatization (9 wk) than it is at sea level due to a higher lactate Ra and disposal from active skeletal muscle. To evaluate this hypothesis, six Danish lowlanders (25 +/- 2 ...

BACKGROUND: Although the pathogenic mechanisms of selective loss of motor neurons in amyotrophic lateral sclerosis (ALS) are unknown, there is increasing evidence for the hypothesis of an oxidative stress-related mitochondrial involvement as key determinant of motor neuron degeneration OBJECTIVE: The aim of our study has been to assess blood levels ...

This study evaluated the reliability and validity of the lactate minimum test (LMT), an incremental test given after lactic acidosis was induced by sprint exercise. This test is purported to accurately estimate the intensity of exercise at which the transport of lactate into and out of the blood is in ...

PURPOSE: The purpose of this study was to examine the upper-body contribution via handgrip to power profiles and blood lactate concentrations during high-intensity cycle ergometry. METHODS: Nine trained male subjects each completed a 20-s high-intensity cycle ergometer test twice, in a random manner, using two protocols, with a handgrip (WG), ...

OBJECTIVE: The anaerobic threshold (AT) is a submaximal index related to endurance exercise performance, which is usually determined by the measurement of blood lactate concentration during an incremental exercise test (lactate threshold [LT]). The LT, and thus the AT, can also be detected noninvasively in normal subjects by means of ...

OBJECTIVE: To investigate the skeletal muscle mitochondrial function in HIV-infected patients with lipodystrophy or elevated p-lactate levels. DESIGN: Eight HIV patients treated with highly active antiretroviral therapy, with lipodystrophy or elevated p-lactate, and eight healthy controls were exposed to incremental exercise until exhaustion. METHODS: Blood samples and gas analysis were ...

This study evaluated lactate disposal via gluconeogenesis as well as effects of FFA availability on gluconeogenesis via pyruvate (GNG(PYR)) in patients with mitochondrial myopathy due to complex I deficiency (CID). The rates of GNG(PYR) were measured in three CID patients and six healthy controls at rest and during 90 min ...

The aim of this study was to investigate the reproducibility of blood lactate measurements, heart rate (HR) and ratings of perceived exertion (RPE) during treadmill exercise at speeds corresponding to the lactate threshold ( v(Th,la)-) and a fixed blood lactate concentration of 4 mmol.l(-1)( v(la)-(,4)). Possible differences in reproducibility related ...

During and after maximal exercise there is a 15-30 % decrease in the metabolic uptake ratio (O(2)/[glucose + 1/2 lactate]) and a net lactate uptake by the human brain. This study evaluated if this cerebral metabolic uptake ratio is influenced by the intent to exercise, and whether a change could ...

The aim of this study was to determine the effects of frequency of verbal encouragement during maximal exercise testing. Twenty-eight participants (12 males, 16 females) aged 20.9 +/- 1.5 years (mean +/- s) performed a maximal exercise test (VO2max) on a treadmill without any verbal encouragement. The participants were matched ...

PURPOSE: This study examined ratings of perceived exertion (RPE) during resistance exercise in women. In addition, changes in blood lactic acid and biceps muscle activity assessed using electromyography (EMG) were investigated as potential mediators of RPE during resistance exercise. METHODS: Twenty female volunteers (age, 25 +/- 4 yr) performed one ...

Painful impulses from tender pericranial muscles may play a major role in the pathophysiology of chronic tension-type headache. Firm evidence for peripheral muscle pathology as a cause of muscle pain and chronic headache is still lacking. Using a microdialysis technique, we aimed to estimate in vivo blood flow and interstitial ...

This study aimed to compare the performance of a new portable lactate analyser against other standard laboratory methods in three conditions, normal (20 +/- 1.3 degrees C; 40 +/- 5 % RH), hot (40 +/- 2.5 degrees C; 40 +/- 5 % RH), and humid (20 +/- 1.1 degrees C; ...

The aim of this study was to investigate the acid-base balance during repeated cycling sprints in children and adults. Eleven boys (9.6 +/- 0.7 yr) and ten men (20.4 +/- 0.8 yr) performed ten 10-s sprints on a cycle ergometer separated by 30-s passive recovery intervals. To measure the time ...

The purpose of this investigation was to compare the blood lactate concentration ([La]), stroke distance (D(s)), and swim index (SI) during an incremental swim test (IST) in elite swimmers who had a loss in mobility (LM) (n = 6) or who had full mobility (FM) (n = 5) of the ...

Hyperlactatemia associated with use of nucleoside analogue reverse transcriptase inhibitors (NRTIs) is not a single entity but a spectrum of abnormalities. The spectrum reflects varying degrees of derangement in systemic homeostasis in the face of primary drug effects on lactate load. Lactic acidosis, characterized by metabolic acidosis, blood lactate above ...

The purpose of this investigation was to observe the effect of hypohydration (-4% body mass) on lactate threshold (LAT) in 14 collegiate athletes (8 men and 6 women; age, 20.9 +/- 0.5 years; height, 171.1 +/- 2.4 cm; weight, 64.8 +/- 2.3 kg; V(O)2 max, 62.8 +/- 1.9 ml x ...

In three separate studies, we have observed that the rise in blood lactate during exercise is correlated to blood viscosity and red cell aggregation. Whether these results were related to an effect of blood rheology on lactate production by muscles or on lactate disappearance remains unknown. The modelling of postexercise ...

OBJECTIVE: Temporary Internal Carotid Artery (ICA) clipping necessary during aneurysm surgery was used as a model to investigate metabolic changes in the human brain during defined episodes of ischaemia. DESIGN: An observational study using intracerebral monitors: PBO2 (Neurotrend) and microdialysis (CMA, Sweden). SUBJECTS: 16 patients monitored during complex aneurysm surgery. ...

To investigate the effects of a single session of prolonged cycle exercise [60% peak O2 uptake (VO2 peak) for 5-6 h] on metabolic adaptations in working vastus lateralis muscle, nine untrained males (peak O2 uptake = 47.2 +/- 1.1 ml x kg(-1) x min(-1), means +/- SE) were examined before ...

Twenty subjects with healthy skin were treated with the following formulations for two weeks: drug-free W/O vehicle, 5% ammonium lactate (CAS 52003-58-4) in W/O vehicle, 5% urea (CAS 57-13-6) in W/O vehicle, 3% ammonium lactate + 3% urea in W/O vehicle, 5% ammonium lactate + 5% urea in W/O vehicle. ...

Lactate is known as the end product of anaerobic glycolysis, a pathway that is of key importance during high intensity exercise. Instead of being a waste product lactate is now regarded as a valuable substrate that significantly contributes to the energy production of heart, non-contracting muscles and even brain. The ...

1. In McArdle's disease, muscle glycogenolysis is blocked, which results in absent lactate and enhanced ammonia production in working muscle. Using McArdle patients as an experimental model, we studied whether lactate and ammonia could be mediators of the exercise pressor reflex. 2. Changes in muscle interstitial ammonia and lactate were ...

Experiments were conducted to determine the physiological responses to exercise of Atlantic sturgeon (Acipenser oxyrhynchus) and shortnose sturgeon (A. brevirostrum). We measured the rates of oxygen consumption and ammonia excretion in both species and a variety of physiological parameters in both muscle (e.g. lactate, glycogen, pyruvate, glucose and phosphocreatine concentrations) ...

The aim of the present study was to test a constant blood withdrawal method (CBWM) to collect blood samples from horses during treadmill exercise. CBWM was performed in 4 Standardbreds and 5 Haflinger horses. A peristaltic pump was used to control blood aspiration from an i.v. catheter via an extension ...

Previous studies have found that administration of dichloroacetate (DCA), an agent that reduces lactic acid generation, increases limb muscle endurance. The purpose of the present study was to determine if this agent also improves respiratory muscle performance. To examine this issue, we determined the effect of DCA administration on the ...

The pathogenic mechanism of selective loss of motor neurones in amyotrophic lateral sclerosis (ALS) is still poorly understood. Recently, research evidence has suggested that mitochondrial dysfunction occurs in central nervous system as well as in peripheral tissues from ALS patients. The aim of our study was to indirectly investigate in ...

The training intensity may affect the monocarboxylate transporters MCT1 and MCT4 in skeletal muscle. Therefore, 20 elite cross-country skiers (11 men and nine women) trained hard for 5 months at either moderate (MIG, 60-70% of VO2max) or high intensity (HIG, 80-90%). The lactate threshold, several performance parameters, and the blood ...

We examined the effects of dynamic one-legged knee extension exercise on mean blood velocity (MBV) and muscle interstitial metabolite concentrations in healthy young subjects (n = 7). Femoral MBV (Doppler), mean arterial pressure (MAP) and muscle interstitial metabolite (adenosine, lactate, phosphate, K(+), pH, and H(+); by microdialysis) concentrations were measured ...

It has been suggested that lactate concentrations may provide a guide to an optimal training intensity. However, lactate concentrations established during incremental exercise in the laboratory are not always indicative of what is occurring during constant-load exercise at the same intensity. Ideally, lactate concentrations should be measured during a training ...

The simultaneous release and uptake of lactate by the heart has been observed both in vivo and ex vivo; however, the pathways underlying these observations have not been satisfactorily explained. Consequently, the purpose of this study was to test the hypothesis that hearts release lactate from glycolysis while simultaneously taking ...

A number of training adaptations in skeletal muscle might be expected to enhance lactate extraction during hyperlactataemia. The aim of the present study was to determine whether resting endurance-trained forearms exhibit an increased net lactate removal during hyperlactataemia. Six racquet-sport players attended the laboratory for two experiments, separated by 2 ...

This study investigated the reproducibility of blood lactate-anchored ratings of perceived exertion (RPE) in seven women of average, and seven of above average cardiorespiratory fitness, [moderate and high maximal oxygen uptake (Mod VO2max and High VO2max, respectively)]. The subjects completed a series of four exercise tests, comprising a VO2max assessment ...

Usually, the lactate stress test is carried under a constant, low workload maintained for 15 min, although there are indications that the lactate response to exercise is a function of the relative workload, and that a workload for only 5 min does not decrease its sensitivity. Thus, this study compared ...

Anecdotal observations suggest that the reduction in peak lactate accumulation in blood ([La]b peak) after exhausting exercise, in chronic hypoxia vs. normoxia, may be related to the duration of the exercise protocol, being less pronounced after short supramaximal exercise than after incremental exercise (IE) lasting several minutes. To test this ...

In cycle exercise, it has been suggested that critical power, maximal lactate steady state, and lactate turnpoint all demarcate the transition between the heavy exercise domain (in which blood lactate is elevated above resting values but remains stable over time) and the very heavy exercise domain (in which blood lactate ...

In red blood cells (RBC) of horses, both lactate-transport activity and lactate accumulation during races vary interindividually. To study whether similar variation in lactate transport is apparent also in RBCs of other racing species, blood samples were collected from 21 reindeer, 40 horses, 31 humans, and 38 dogs. Total lactate-transport ...

Genetic analysis for mastitis resistance was studied from two data sets. Firstly, risk factors for different mastitis traits, i.e. culling due to clinical or chronic mastitis and subclinical mastitis predicted from somatic cell count (SCC), were explored using data from 957 first lactation Lacaune ewes of an experimental INRA flock ...

BACKGROUND: The forearm exercise test is a common investigation that allows detection of some metabolic myopathies. It is not completely standardized and, when performed in ischemic conditions, may induce rhabdomyolysis in patients with glycogenosis. OBJECTIVE: To develop a standardized non-ischemic exercise test for a safe screening of patients with exercise ...

Relationships between perceived exertion and blood lactate have usually been studied in laboratory or training contexts but not in competition, the most important setting in which sports performance is evaluated. The purpose of this study was to examine the relationships between psychological and physiological indices of the physical effort in ...

PURPOSE: Maximal lactate steady state (MLSS) is the highest exercise intensity at which blood lactate concentration (HLa) remains stable. In this study, we examined the validity of simulated 5-km and 40-km time trials (TT) as methods for estimating average speed at MLSS in cyclists. METHODS: Nine trained cyclists reported to ...

BACKGROUND: Blood lactate concentration (BLC) can be used to monitor relative exercise intensity. The highest BLC representing an equilibrium between lactate production and elimination is termed maximal lactate steady state (MLSS). MLSS is used to discriminate qualitatively between continuous exercise, which is limited by stored energy, from other types of ...

Purine degradation occurs during strenuous muscle exercise and plasma levels of hypoxanthine (HX), purine degradation intermediate, increase. Purine nucleotide degradation has not been investigated in patients with essential hypertension (HTN). The present study determined whether purine nucleotide degradation is altered in patients with HTN. Cardiopulmonary exercise test was performed with ...