The relationship between sire predicted transmitting ability (PTA) for somatic cell score (SCS) and occurrence of mastitis in daughters was characterized with 304 Holsteins first freshening since 1991 in the Virginia Tech dairy herd. No direct sire selection for PTA SCS was practiced in the herd. Linear regressions of first ...

The physiological profiles of 17 open grade (OG) and 13 reserve grade (RG) male surfboat rowers (SBR) aged 19-44 years were determined and compared. Parameters investigated included anthropometry, agility, isometric strength, flexibility, rowing ergometer performance (MT), peak VO2 and arterialised blood pH, lactate and bicarbonate. Means were compared using t-tests. ...

Crustacean discards experience stress during commercial fishing operations, due to increased exercise while in the trawl and aerial exposure during sorting of the catch. Physiological stress and recovery were assessed following trawling of two ecologically important decapod species, regularly discarded in the Clyde Nephrops fishery. Haemolymph samples taken from trawled ...

In a double-blinded, placebo-controlled, crossover study in seven mitochondrial myopathy patients (MM), we investigated whether lowering of lactate with dichloroacetate (DCA) can improve exercise tolerance and oxidative capacity in MM. DCA lowered plasma lactate at rest and during exercise (from 10.5 +/- 2.0 to 5.0 +/- 1.6 mM; p = ...

The effects of 4 weeks of endurance training in conditions of normoxia or hypoxia on muscle characteristics and blood lactate responses after a 5-min constant-load exercise (CLE) at 90% of the power corresponding to the maximal oxygen uptake were examined at sea-level in 13 sedentary subjects. Five subjects trained in ...

The superficial supramammary lymph nodes of 54 lactating dairy cows were examined ultrasonographically with a 7.5 MHz linear transducer; each node was measured in two planes within 24 hours of recording the milk somatic cell count. In most cows, the nodes were well demarcated from the surrounding tissue. The parenchyma ...

The effects of endurance training (running 40 m/min grade for 60 min, 5 days/wk for 8 wk) on skeletal muscle lactate removal was studied in rats by utilizing the isolated hindlimb perfusion technique. Hindlimbs were perfused (single-pass) with Krebs-Henseleit bicarbonate buffer, fresh bovine erythrocytes (hematocrit approximately 30%), 10 mM lactate, ...

Whole body oxygen consumption and some hemolymph parameters such as pH, partial pressure of gases, level of ions and lactate were measured in the estuarine crab Chasmagnathus granulata after both acute (96 h) and chronic (2 weeks) exposure to cadmium at concentrations ranging from 0.4 to 6.3 mg/l. In all ...

Clough et al. (1997) reported that 95% of lactate values obtained using an Accusport analyser may be up to 2.6 mM below or 2.1 mM above YSI 2300 analyser values over the range 0-16 mM. This variability is substantial and unsuitable for research purposes, The objectives of this study were ...

A field trial was conducted to examine the effect of extended calving interval (CI) on production and profitability of high yielding cows (n = 937). First insemination was performed at 154 and 93 d postpartum (pp), for treatment and control primiparous cows, respectively, and at 124 and 71 d pp ...

PURPOSE: To determine whether lactate profiling could detect changes in discrete aspects of endurance fitness in world-ranked swimmers during a season. METHODS: Eight male and four female Australian National Team swimmers aged 20--27 yr undertook a 7 x 200-m incremental swimming step test on four occasions over an 8-month period ...

OBJECTIVE: This study investigated the blood lactate accumulation during two wheelchair-racing protocols. During exercise, energy is required, which causes metabolism to increase and blood lactate to accumulate. Proper training can reduce the amount of blood lactate accumulation and increase tolerance to blood lactate accumulation during aerobic exercise. METHODS: Eleven male ...

OBJECTIVE: To study the effects of human pregnancy on metabolic and respiratory responses to maximal cycle ergometer testing and to test the hypothesis that the respiratory exchange ratio at maximal exercise and peak postexercise lactate concentration are lower in the pregnant compared with the nonpregnant state and that these effects ...

Tai Chi Chuan (TCC) is a popular Chinese conditioning exercise, however, its exercise intensity remains controversial. The objective of this study was to determine the exercise intensity of Yang TCC by measuring heart rate (HR) responses and oxygen consumption (VO2) during practice. Fifteen men aged 39.9 +/- 9.5 yrs (range ...

BACKGROUND AND PURPOSE: Decreases in N-acetyl aspartate (NAA) as seen by proton MR spectroscopy are found in hippocampal sclerosis, and elevated levels of lipids/lactate have been observed after electroconvulsive therapy. Our purpose was to determine whether increased levels of lipids/lactate are found in patients with acute seizures of hippocampal origin. ...

At the Third Pan-American Congress of Sport Physicians in Chicago in 1959 we reported the physiological and clinical significance of the spiroergometric determination of the aerobic-anaerobic turnover point for judging the performance of sick and healthy persons for the first time. In this context a distinction was made between a ...

The present study was designed in order to examine the objectivity and reliability of the individual anaerobic threshold (IAT) as well as its resistance against several interfering factors: missing exhaustion, preliminary exercise, longer step duration, and lower speed increment. 87 male and 24 female runners and triathletes were examined. They ...

A strong relationship between aerobic fitness and the aerobic response to repeated bouts of high intensity exercise has been established, suggesting that aerobic fitness is important in determining the magnitude of the oxidative response. The elevation of exercise oxygen consumption (VO2) is at least partially responsible for the larger fast ...

Many physiological markers vary similarly during training and overtraining. This is the case for the blood lactate concentration ([La-]b), since a right shift of the lactate curve is to be expected in both conditions. We examined the possibility of separating the changes in training from those of overtraining by dividing ...

To assess the eventual effects of acute oral salbutamol intake on performance and metabolism during submaximal exercise, nine healthy volunteers completed two cycling trials at a power corresponding to 80-85% VO2max, after either placebo (Pla) or salbutamol (Sal, 6 mg) treatment, according to a double-blind randomized protocol. Blood samples were ...

The purpose of this study was to measure O2 consumption of nonexercising skeletal muscles (VO2nonex) at rest and after aerobic exercise and to investigate the stimulant factors of O2 consumption. In experiment 1, we measured the resting metabolic rate of the finger flexor muscles in seven healthy males by 31P-magnetic ...

During the onset of exercise in hypoxia, the increased lactate accumulation is associated with a delayed activation of pyruvate dehydrogenase (PDH; Parolin ML, Spreit LL, Hultman E, Hollidge-Horvat MG, Jones NL, and Heigenhauser GJF. Am J Physiol Endocrinol Metab 278: E522-E534, 2000). The present study investigated whether activation of PDH ...

BACKGROUND: The individual anaerobic threshold (IAT) is defined (18) as the highest metabolic rate where blood lactate (La) concentrations are maintained at a steady-state during prolonged exercise. Stegmann et al.'s (18) method to detect IAT, using La-performance relationship during incremental graded exercise, is based on the assumption that La is ...

The purpose of this study was to investigate the distribution of lactate in plasma and red blood cells (RBC) in capillary blood during and after incremental exercise. We measured capillary plasma lactate and whole blood lactate of 10 subjects during incremental treadmill running and the first 20 min of recovery. ...

PURPOSE: This study examined the effect of training status and relative exercise intensity on physiological responses to endurance exercise in humans. METHODS: Seven endurance trained (TR: peak oxygen uptake [VO2peak] = 65.8 +/- 2.4 mL x kg(-1) min(-1)) and six untrained (UT: VO2peak = 46.2 +/- 1.9 mL x kg(-1) ...

BACKGROUND: Endurance sports require a variety of physiological adaptations. OBJECTIVE: To examine the structural and functional heart adaptations and their hemodynamic implications in triathletes. PATIENTS AND METHODS: A group of 52 male triathletes was compared with a control group of 22 healthy male nonathletes. All of the subjects were given ...

Nicotinic acid (niacin) has been shown to decrease myocyte injury. Because interventions that lower the cytosolic NADH/NAD(+) ratio improve glycolysis and limit infarct size, we hypothesized that 1) niacin, as a precursor of NAD(+), would lower the NADH/NAD(+) ratio, increase glycolysis, and limit ischemic injury and 2) these cardioprotective benefits ...

OBJECTIVE: To compare the efficacy in runners of two relaxation techniques with regard to exercise reactivity and recovery after exercise. METHODS: Thirty one adult male runners were studied prospectively for six months in three groups practising either meditation (n = 11) or autogenic training (n = 11) or serving as ...

Changes in physiological variables during a 60-min continuous test at maximal lactate steady state (MLSS) were studied using highly conditioned cyclists (1 female and 9 males, aged 28.3 +/- 8.1 years). To determine power at MLSS, we tested at 8-min increments and interpolated the power corresponding to a blood lactate ...

1. We evaluated the plasma ammonia response to constant exercise at different intensities. Ten healthy male volunteers were asked to perform constant exercise for 15 min at five different intensities: 80, 90, 100, 110 and 120% of their ventilatory threshold (VT). Blood concentrations of lactate, ammonia and hypoxanthine were measured ...

We investigated the effects of a single bout of non-exhaustive exercise (25 m x min(-1), 10% grade, for 30 min) on the initial rates of lactate uptake in rat skeletal muscle sarcolemmal vesicles and the monocarboxylate transporter 1 (MCT1) content in isolated hindlimb muscles in relation to the exercise-induced oxidative ...

The so-called excess-CO2 in physical exertion results stoichiometrically directly from the quantity of protons bound in bicarbonate buffering. This situation is used in determining the ventilatory threshold (VT). However, the extent to which the degree and increase characteristics of excess-CO2 can be used as an equivalent to blood lactate concentrations ...

The purpose of this study was to determine whether the critical swimming velocity (Vcrit) corresponds to the velocity at lactate threshold (V-LT) in elite triathletes. Eight elite triathletes (5 male, 3 female; age 26 +/- 4 years; height 1.7 +/- 0.1 m and body mass 75 +/- 4 kg) participated ...

The aim of this longitudinal study was to analyze the changes in several metabolic and neuromuscular variables in response to endurance training during three defined periods of a full sports season (rest, precompetition and competition). The study population was formed by thirteen professional cyclists (age +/- SEM: 24+/-1 years; mean ...

The effects of endurance training on lactate transport capacity remain controversial. This study examined whether endurance training 1) alters lactate transport capacity, 2) can protect against exhaustive exercise-induced lactate transport alteration, and 3) can modify heart and oxidative muscle monocarboxylate transporter 1 (MCT1) content. Forty male Wistar rats were divided ...

This article summarizes previous studies on blood ammonia levels in relation to exercise. The dynamics of blood ammonia were reviewed with consideration to its production, removal, and distribution in various tissue compartments. During intense exercise, the primary source of ammonia is adenosine monophosphate deamination. Catabolism of branched-chain amino acids becomes ...

PURPOSE: In a previous study, we showed that when six different plasma lactate parameters (LPs) were compared, the LP determined by the Dmax method was the best predictor of 1-h cycling performance in women. The present study extended these findings to determine whether or not the relationship between the following ...

PURPOSE: The maximal lactate steady state (MLSS) corresponds to the highest workload that can be maintained over time without a continual blood lactate accumulation. MLSS and MLSS intensity have been speculated to depend on performance. Experimental proof of this hypothesis is missing. METHODS: 33 male subjects (age: 23.7 +/- 5.5 ...

Promotion of uptake of essential metabolites is a possible reason for the general stimulation of gonococcal metabolism which is caused by lactate (1 mM) in a defined medium containing glucose (5 mM). However, although uptake of(14)C adenine by gonococci [strain BS4(agar)] held for 4 or 7 min at 37 degrees ...

The associations between velocity during a standardized, submaximal 800-m exercise test and blood lactate concentration after exercise were investigated in Thoroughbred racehorses on sand and grass racetracks. Predicted lactate concentrations for each horse's exercise test velocity were calculated from the line of best fit derived from results at each racetrack. ...

PURPOSE: Relative to healthy control individuals with normal hemoglobin (Hb), patients carrying the double heterozygous form of sickle cell disease (HbSC) display an impaired oxygen transport capacity. The present study was undertaken to determine the influence of the decreased oxygen availability associated with the presence of HbSC on the cardiorespiratory ...

The "lactate shuttle hypothesis" holds that lactate plays a key role in the distribution of carbohydrate potential energy that occurs among various tissue and cellular compartments such as between: cytosol and mitochondria, muscle and blood, blood and muscle, active and inactive muscles, white and red muscles, blood and heart, arterial ...

PURPOSE: This paper examines the production of lactate in human skeletal muscle over a range of power outputs (35-250% VO2max) from an enzymatic flux point of view. The conversion of pyruvate and NADH to lactate and NAD in the cytoplasm of muscle cells is catalyzed by the near-equilibrium enzyme lactate ...

To evaluate the effects of endurance training on the expression of monocarboxylate transporters (MCT) in human vastus lateralis muscle, we compared the amounts of MCT1 and MCT4 in total muscle preparations (MU) and sarcolemma-enriched (SL) and mitochondria-enriched (MI) fractions before and after training. To determine if changes in muscle lactate ...

The hyperoxia-improved tolerance to maximal aerobic performance was studied in relation to exercising muscle metabolic state. Five students were submitted to four different tests on a cycle ergometer, each being conducted under normoxia and hyperoxia (60% FiO2) on separate days: Test 1, a progressive exercise until exhaustion to determine the ...

The aim of this study was to assess the responses of blood lactate and pyruvate during the lactate minimum speed test. Ten participants (5 males, 5 females; mean +/- s: age 27.1+/-6.7 years, VO2max 52.0+/-7.9 ml x kg(-1) x min(-1)) completed: (1) the lactate minimum speed test, which involved supramaximal ...

This study evaluated the effects of hyperoxia (inspired oxygen fraction = 40%) on performance during a simulated firefighting work circuit (SFWC) consisting of five events. On separate days, 17 subjects completed at least three orientation trials followed by two experimental trials while breathing either normoxic (NOX) and hyperoxic (HOX) gas ...

OBJECTIVE: To determine lactate breakpoint of horses and test for effects of training and dietary supplementation with corn oil on that breakpoint. ANIMALS: 7 healthy Arabian horses. PROCEDURES: Horses received a control diet (n = 4) or a diet supplemented with 10% corn oil (4). A training program, which comprised ...

OBJECTIVE: To examine the validity of using blood taken from the toe for the assessment of plasma lactate concentration in rowers. To achieve this, values were compared with those taken from the fingertip and earlobe. METHODS: Nine subjects exercised at two separate submaximum workloads on the Concept II rowing ergometer. ...

After intense exercise muscle may give off hydrogen ions independently of lactate, perhaps by a mechanism involving sodium ions. To examine this possibility further five healthy young men cycled for 2 min to exhaustion. Blood was drawn from catheters in the femoral artery and vein during exercise and at 1-h ...