Measurement Of Lactate Concentration Research Articles

Acute Effects of Overload Running on Physiological and Biomechanical Variables in Trained Trail Runners

Background: The biomechanical and physiological adaptations to resisted running have been well documented in sprinting; however, their impact at submaximal speeds, such as those typical of long-distance running, remains unclear. This study aimed to evaluate the impact of running with a weighted vest, loaded with 5% and 10% of body mass, on the physiological and mechanical variables of trained trail runners. Methods: Fifteen male trail runners completed an incremental protocol to exhaustion on a treadmill with 0%, 5%, and 10% of their body mass (BM), in random order, with one week of separation between the tests. The maximality of the test was confirmed by measuring lactate concentrations at the end of the test. Oxygen consumption (V˙O2) and respiratory exchange ratio (RER) were recorded using a portable gas analyzer (Cosmed K5), and ventilatory thresholds 1 and 2 (VT1, VT2) were calculated individually. Running power was averaged for each speed stage using the Stryd device. Finally, the peak values and those associated with VT1 and VT2 for speed, power (absolute and normalized by body mass), V˙O2, RER, and the cost of transport (CoT) were included in the analysis. Results: One-way repeated-measures ANOVA revealed a detrimental effect of the extra load on maximum speed and speed at ventilatory thresholds (p ≤ 0.003), with large effect sizes (0.34–0.62) and a nonlinear trend detected in post hoc analysis. Conclusions: Using running power to control the intensity of effort while carrying extra weight provides a more stable metric than speed, particularly at aerobic intensities. Future research in trail running should investigate the effects of weighted vests across various terrains and slopes.

Arterial to jugular-bulb lactate difference in patients undergoing elective brain tumor craniotomy.

Hyperlactatemia is common during tumor craniotomy, but the underlying pathophysiology is unclear. This study measured simultaneous arterial and jugular-bulb lactate concentrations in patients undergoing brain tumor craniotomy to investigate the hypothesis that hyperlactatemia was associated with a net cerebrovascular lactate input. In 20 patients, arterial and jugular-bulb blood was collected hourly from the start of surgery to 6 h postoperatively for measurement of lactate, glucose, and oxygen concentration. For each marker, data were analyzed using a linear mixed-effects model with jugular-bulb concentration as dependent variable, arterial concentration as fixed effect, and patient as random effect. Furthermore, we generated regression lines between arterial and jugular-bulb concentrations. The slope of the regression line between arterial and jugular-bulb lactate was 0.95 (95% CI 0.93-0.97, R2 = 0.98), indicating that increasing arterial lactate levels were associated with an increasingly positive net cerebrovascular balance (net input). The line crossed the identity line at 2.86 (95% CI 0.57-5.16) mmol/L, indicating that lower levels of lactate were associated with a negative net cerebrovascular balance (net output). This suggests a switch from net lactate output during normolactatemia towards net input during hyperlactatemia. Hyperlactatemia in tumor-craniotomy patients probably does not originate from the brain.

Optimization and adaptation of amperometric biosensor based on lactate oxidase for measuring lactate concentration in blood serum samples

Optimization and adaptation of amperometric biosensor based on lactate oxidase for measuring lactate concentration in blood serum samples

The Influence of Pedaling Frequency on Blood Lactate Accumulation in Cycling Sprints.

Anaerobic performance diagnostics in athletes relies on accurate measurements of blood lactate concentration and the calculation of blood lactate accumulation resulting from glycolytic processes. In this study, we investigated the impact of pedaling frequency on blood lactate accumulation during 10-second maximal isokinetic cycling sprints. Thirteen trained males completed five 10-second maximal isokinetic cycling sprints on a bicycle ergometer at different pedaling frequencies (90 rpm, 110 rpm, 130 rpm, 150 rpm, 170 rpm) with continuous power and frequency measurement. Capillary blood samples were taken pre-exercise and up to 30 minutes post-exercise to determine the maximum blood lactate concentration.Blood lactate accumulation was calculated as the difference between maximal post-exercise and pre-start blood lactate concentration. Repeated measurement ANOVA with Bonferroni-adjusted post hoc t-tests revealed significant progressive increases in maximal blood lactate concentration and accumulation with higher pedaling frequencies (p<0.001; η2+>+0.782).The findings demonstrate a significant influence of pedaling frequency on lactate accumulation, emphasizing its relevance in anaerobic diagnostics. Optimal assessment of maximal lactate formation rate is suggested to require a pedaling frequency of at least 130 rpm or higher, while determining metabolic thresholds using the maximal lactate formation rate may benefit from a slightly lower pedaling frequency.

MnFe@N-CNTs Based Lactate Biomicrochips for Nonintrusive and Onsite Periodontitis Diagnosis.

In clinical settings, saliva has been established as a straightforward, noninvasive medium for diagnosing periodontitis. However, the precise diagnosis is often hampered by the absence of a specialized analyzer capable of detecting low concentrations of biomarkers typically found in saliva. In this study, we present a noninvasive, on-site screen-printed biomicrochip specifically engineered for the precise and sensitive quantification of lactate concentrations in saliva, a critical biomarker in the diagnosis of periodontitis. The microchip is constructed using a nanostructured ink formulation that includes MnFe@N-doped carbon nanotubes (MnFe@N-CNTs). These MnFe@N-CNTs exhibit a high degree of graphitization and low electrical resistance, significantly augmenting the electrocatalytic efficiency of the enzymatic reaction of lactate. This results in doubled sensitivity and a detection limit that surpasses those of the current advanced salivary assay methods. Remarkably, within just 30 s, the biomicrochip can quantitatively and precisely measure lactate concentrations in the saliva of 10 patients, which provides valuable insights into the severity of their periodontitis. This biosensor holds excellent potential for large-scale production and could broaden the scope of biomarker recognition, paving the way for the analysis of a wider range of oral diseases.

Correlation of detrended fluctuation analysis alpha 1 with blood lactate concentration in field standardised exercise tests in sport horses

Abstract Methods to determine exercise intensity thresholds, such as the aerobic and anaerobic threshold, that separate different exercise intensities in exercising horses in the field setting or on the treadmill often require equipment, standardised conditions and/or blood sampling. Detrended fluctuation analysis (DFA) is a heart rate variability variable proposed as a non-invasive tool for exercise intensity monitoring and with a potential association with exercise intensity thresholds and fatigue. The objectives of this study were to (1) describe the first component of DFA (DFA-α1) during standardised field incremental exercise tests in sport horses in active Eventing competition and in sport horses ridden without the goal of participating in competitions, and (2) to determine if DFA-α1 is associated with blood lactate concentration. Null hypotheses of the study were that (1) DFA-α1 is not correlated with blood lactate concentration measurements and (2) the correlation between DFA-α1 and blood lactate concentration is not stronger than the one between blood lactate concentration and heart rate or blood lactate concentration and speed. An in vivo observational study was performed analysing exercising electrocardiograms obtained in 59 standardised exercise tests in the field. DFA-α1 was significantly and moderately correlated with blood lactate concentration (, ). A strong correlation was observed between blood lactate concentration and speed (, ), as well as between blood lactate concentration and heart rate (, ). DFA-α1 correlation with blood lactate concentration was moderate but weaker than the correlation of blood lactate concentration and heart rate or blood lactate concentration and speed. DFA-α1 was not a useful surrogate of blood lactate concentration in field incremental standardised tests used for sport horses in this setting.

Reduced graphene oxide-functionalized polymer microneedle for continuous and wide-range monitoring of lactate in interstitial fluid

Despite substantial developments in minimally invasive lactate monitoring microneedle electrodes, most such electrode developments have focused on either sensitivity or invasiveness while ignoring a wide range of detection, which is the most important factor in measuring the normal range of lactate in interstitial fluid (ISF). Herein, we present a polymer-based planar microneedle electrode fabrication using microelectromechanical and femtosecond laser technology for the continuous monitoring of lactate in ISF. The microneedle is functionalized with two-dimensional reduced graphene oxide (rGO) and electrochemically synthesized platinum nanoparticles (PtNPs). A particular quantity of Nafion (1.25 wt%) is applied on top of the lactate enzyme to create a diffusion-controlled membrane. Due to the combined effects of the planar structure of the microneedle, rGO, and membrane, the biosensor exhibited excellent linearity up to 10 mM lactate with a limit of detection of 2.04 μM, high sensitivity of 43.96 μA mM−1cm−2, a reaction time of 8 s and outstanding stability, selectivity, and repeatability. The feasibility of the microneedle is evaluated by using it to measure lactate concentrations in artificial ISF and human serum. The results demonstrate that the microneedle described here has great potential for use in real-time lactate monitoring for use in sports medicine and treatment.

Estimation of physiological exercise thresholds based on dynamical correlation properties of heart rate variability.

Aerobic and anaerobic thresholds of the three-zone exercise model are often used to evaluate the exercise intensity and optimize the training load. Conventionally, these thresholds are derived from the respiratory gas exchange or blood lactate concentration measurements. Here, we introduce and validate a computational method based on the RR interval (RRI) dynamics of the heart rate (HR) measurement, which enables a simple, yet reasonably accurate estimation of both metabolic thresholds. The method utilizes a newly developed dynamical detrended fluctuation analysis (DDFA) to assess the real-time changes in the dynamical correlations of the RR intervals during exercise. The training intensity is shown to be in direct correspondence with the time- and scale-dependent changes in the DDFA scaling exponent. These changes are further used in the definition of an individual measure to estimate the aerobic and anaerobic threshold. The results for 15 volunteers who participated in a cyclo-ergometer test are compared to the benchmark lactate thresholds, as well as to the ventilatory threshods and alternative HR-based estimates based on the maximal HR and the conventional detrended fluctuation analysis (DFA). Our method provides the best overall agreement with the lactate thresholds and provides a promising, cost-effective alternative to conventional protocols, which could be easily integrated in wearable devices. However, detailed statistical analysis reveals the particular strengths and weaknessess of each method with respect to the agreement and consistency with the thresholds-thus underlining the need for further studies with more data.

Advancements in wearable technology for monitoring lactate levels using lactate oxidase enzyme and free enzyme as analytical approaches: A review

Lactate is a metabolite that holds significant importance in human healthcare, biotechnology, and the food industry. The need for lactate monitoring has led to the development of various devices for measuring lactate concentration. Traditional laboratory methods, which involve extracting blood samples through invasive techniques such as needles, are costly, time-consuming, and require in-person sampling. To overcome these limitations, new technologies for lactate monitoring have emerged. Wearable biosensors are a promising approach that offers non-invasiveness, low cost, and short response times. They can be easily attached to the skin and provide continuous monitoring. In this review, we evaluate different types of wearable biosensors for lactate monitoring using lactate oxidase enzyme as biological recognition element and free enzyme systems.

Measurement of sweat lactate levels in exercise and non-exercise activities using capillary electrophoresis system with contactless conductivity detection and cyclodextrin-modified buffer

This study presents the analysis of lactate in sweat using capillary electrophoresis with contactless conductivity detection. Two cyclodextrin (CD) compounds, carboxymethyl-β-cyclodextrin sodium salt (CM-β-CD) and heptakis (2,3,6-tri-O-benzoyl)-β-cyclodextrin (TRIME-β-CD), were evaluated as buffer modifiers for the separation of chloride, nitrate, sulfate, oxalate, maleate, acetate, lactate, and phosphate anions. The concentrations of these modifiers were tested at 0.05, 0.1, and 0.5 mM for eight anions separation. The buffer was 40.0 mM MES/L-His (pH 6.0) with 0.05 mM CTAB, resulting in anodic separation. Due to separation efficiency in resolving lactate and phosphate peaks, TRIME-β-CD at a concentration of 0.1 mM was selected as the suitable buffer additive for sweat lactate analysis. The calibration of the developed method, using maleate as an internal standard, resulted in the linear ranges of 0.1–5.0 mM, r2 of 0.9999, and an instrumental LOD of 0.042 mM. The intra-day and inter-day precisions of the relative migration time (RMT) were 0.3–0.4% and 3–4% RSD, respectively. Lactate levels in sweat samples from the same group of volunteers were measured after two distinct activities: exercise (after running) and non-exercise (after sauna). For non-exercise activities, lactate concentrations ranged from 15 ± 1 mM to 36 ± 2 mM. While, after exercise, the concentrations were between 26 ± 1 mM and 136 ± 1 mM. Further evaluation of the stability of sweat storage for monitoring lactate contents, it was found that the changes in lactate levels were insignificant when stored for up to 24 weeks at 4 °C. This was confirmed by paired t-tests (t-stat ragnes from -0.59 to 2.49; t-critical = 2.57, P = 0.05). The measured lactate concentrations from volunteers were significantly higher, approximately 2–6 times, in exercise activities compared to non-exercise activities. This substantial difference in lactate secretion indicates a clear distinction in the factors that stimulate sweat lactate production. To evaluate the intensity of exercise based on lactate levels in sweat, a proposed cut-off level of 36.0 mM, with a decision limit of 40.0 mM, can be proposed.

Continuous Measurement of Lactate Concentration in Human Subjects through Direct Electron Transfer from Enzymes to Microneedle Electrodes.

Microneedle lactate sensors may be used to continuously measure lactate concentration in the interstitial fluid in a minimally invasive and pain-free manner. First- and second-generation enzymatic sensors produce a redox-active product that is electrochemically sensed at the electrode surface. Direct electron transfer enzymes produce electrons directly as the product of enzymatic action; in this study, a direct electron transfer enzyme specific to lactate has been immobilized onto a microneedle surface to create lactate-sensing devices that function at low applied voltages (0.2 V). These devices have been validated in a small study of human volunteers; lactate concentrations were raised and lowered through physical exercise and subsequent rest. Lactazyme microneedle devices show good agreement with concurrently obtained and analyzed serum lactate levels.

Metabolomic profiling of cardiac allografts after controlled circulatory death

Assessment of myocardial viability during ex situ heart perfusion (ESHP) is based on the measurement of lactate concentrations. As this provides with limited information, we sought to investigate the metabolic signature associated with donation after circulatory death (DCD) and the impact of ESHP on the myocardial metabolome. Porcine hearts were retrieved either after warm ischemia (DCD group, N=6); after brain-stem death (BSD group, N=6); or without DCD nor BSD (Control group, N=6). Hearts were perfused using normothermic oxygenated blood for 240 minutes. Plasma and myocardial samples were collected respectively every 30 and 60 minutes, and analyzed by an untargeted metabolomic approach using liquid chromatography coupled to high-resolution mass spectrometry. Median duration of warm ischemia was 23 minutes [19-29] in DCD animals. Lactate level within myocardial biopsies was not significantly different between groups at T0 (p=0.281), and remained stable over the 4-hour period of ESHP. More than 300 metabolites were detected in plasma and heart biopsy samples. Compared to BSD animals, metabolomics changes involving energy and nucleotide metabolisms were observed in plasma samples of DCD animals before initiation of ESHP, whereas 2 metabolites (inosine monophosphate and methylbutyrate) exhibited concentration changes in biopsy samples. Normalization of DCD metabolic profile was remarkable after 4 hours of ESHP. A specific metabolic profile was observed in DCD hearts, mainly characterized by an increased nucleotide catabolism. DCD and BSD metabolomes proved normalized during ESHP. Complementary investigations are needed to correlate these findings to cardiac performances.

Admission lactate concentration has predictive value for death or severe complications within 30 days after admission in cattle with long-bone fractures.

To determine the prognostic value of lactate concentration measurements at admission in cattle with long-bone fractures. 43 cattle with long-bone fractures between July 2016 and Dec 2018. In this prospective cohort study, lactate concentration was measured in systemic venous blood and locally in capillary blood sampled from the fractured and contralateral limbs of cattle and assessed for outcome prediction. The cutoff value was determined by maximizing the Youden index from receiver-operating characteristic curves. Multivariable logistic regression was employed to verify whether higher lactate concentrations compared with the cutoff value were an independent risk factor for poor outcomes at 30 days or 3 years after admission. Poor outcome was associated with higher capillary lactate concentration in the fractured limb (P < .001) and greater difference with systemic blood (P = .005). A cutoff value of lactate difference ≥ 2.4 mmol/L (sensitivity = 0.80; specificity = 0.965) between capillary lactate in the fractured limb and systemic blood was the best predictor of death ≤ 30 days after admission (P < .001). Multivariable analysis revealed that this cutoff value was an independent risk factor for 30-day and 3-year outcomes (P < .001). Admission blood lactate concentration difference ≥ 2.4 mmol/L between the fractured limb and systemic blood was a robust and independent predictor of outcome for cattle of the present report. Lactate metabolism is locally impaired in fractured limbs of nonsurviving or at higher complication risk cattle, which may help identify patients at high risk for poor outcomes.

Short-Term Storage of Mobilized Peripheral Blood Stem Cells in a Closed System Changes the Microenvironment and May Affect the Quantity of CD34+ and CD34+CD38-CD45RA-CD90+ Cells

Hypoxic conditions preserve the multipotency and self-renewing capacity of murine bone marrow and human cord blood stem cells. Blood samples stored in sealed blood gas tubes become hypoxic as leukocytes metabolize and consume oxygen. Taken together, these observations suggest that peripheral blood stem cell (PBSC) samples stored under airtight conditions become hypoxic, and that the stem cells contained may undergo qualitative or quantitative changes. This study aimed to determine the effect of storage for 8 hours in a sealed system on PBSC samples. Granulocyte colony-stimulating factor-mobilized PBSC samples were collected prospectively from 9 patients with myeloma or amyloidosis prior to apheresis, followed by measurement of CO2, O2, hydrogen ion (pH), lactate, and glucose concentrations in the blood and immunophenotyping of stem cell and multipotent progenitor cell populations before and after 8 hours of storage in sealed blood collection tubes. Blood concentrations of O2 and glucose and pH measurements were significantly decreased, whereas concentrations of CO2 and lactate were significantly increased after storage. Significantly higher concentrations of CD34+ cells (552 ± 84 cells/106total nucleated cells [TNCs] versus 985 ± 143 cells/106TNCs; P=.03), CD34+CD38- cells (98 ± 32 cells/106TNCs versus 158 ± 52 cells/106TNCs; P=.03), CD34+CD38+ cells (444 ± 92 cells/106TNCs versus 789 ± 153 cells/106TNCs; P=.03), and CD34+CD38-CD45RA-CD90+ cells (55 ± 17 cells/106TNCs versus 89 ± 25 cells/106TNCs; P=.02) were detected after 8 hours of storage. The changes in concentrations of CD34+CD38+ cells and CD34+ cells were inversely associated with the change in glucose concentration (P=.003 and P < .001, respectively) and positively associated with the change in lactate concentration (P=.01 and P <.001, respectively) after 8 hours of airtight storage. Storage of PBSC samples in a sealed, airtight environment is associated with microenvironmental changes consistent with hypoxia and increased concentrations of immunophenotypically defined stem cells. These results may have clinical implications with regard to the collection and processing of stem cell products and warrant confirmation with functional and mechanistic studies.

Non-Invasive Lactate Monitoring System Using Wearable Chipless Microwave Sensors With Enhanced Sensitivity and Zero Power Consumption.

Monitoring lactate levels is an established method for determining hyperlactatemia in critically ill patients and assessing aerobic fitness. It is a widely used gold-standard technique in both professional and serious amateur sports. Non-invasive real-time lactate monitoring offers significant advantages over the current technology of finger-prick blood sampling. Possible candidate technology for developing non-invasive real-time lactate monitoring should be highly sensitive, flexible, and capable of real-time monitoring of lactate levels in interstitial fluid or within specific working muscle groups depending on the type of sport. Herein we describe a planar, flexible, passive, chipless tag resonator that is electromagnetically coupled to a reader placed in proximity to the lactate sensor tag. The tag resonator is a thin metallic tracing that can be taped on the skin. The resonance frequency of the tag fluctuates proportionately with changing lactate concentrations in a solution mimicking human interstitial fluid with very high sensitivity. The spectrum of the tag is reflected in the spectrum of the reader, which is a planar microwave resonator designed at a different frequency. The reader could be embedded in a cellphone or an application-specific wearable device for data communication and processing. The tag can accurately and reproducibly measure lactate concentrations in the range of 1 to 10 mM, which is in the physiological range of lactate observed at rest and during intense physical activity. Furthermore, the chrematistics of this technology will allow monitoring of lactate in specific working muscle groups.

Development, validation and application of a GC-MS method for quantification of glucose and lactate in vitreous humor

Develop and apply a GC-MS method for quantifying glucose and lactate in vitreous humor. In routine forensic toxicological screening, glucose and lactate are measured in vitreous humor to evaluate the ante-mortem glycaemic status and to identify possible lactate acidosis. Concentrations for both endogenous compounds are required in the assessment of hypo-, normo- or hyperglycaemic status before death. In our laboratory, no in-house chromatographic method was available and diluted vitreous humor samples had to be analysed by an external laboratory, using a spectrophotometric method validated for serum. Starting from a GC-MS method available for GHB and BHB, we investigated the simultaneous measurement of glucose and lactate to increase sample throughput. An analytical method was developed for analysis of glucose and lactate, based on an available GC-MS method used in-house for other analytes and on literature (Shojaee-Moradie et al., Journal of Mass Spectrometry 1996;31:961–966), employing a combination of two derivatisation reactions. Glucose required both oxime and trimethylsilyl derivatisation to achieve compatibility with GC-MS. For lactate, only the silylation step was necessary. Method validation was carried out using in-house prepared quality control samples. Authentic vitreous humor samples ( n = 100) were analysed in parallel between October 2021 and April 2022, comparing the results of the newly developed method to those from the external laboratory. The derivatisation time and calibration model were optimised. The method was validated according to the guideline on bioanalytical method validation provided by the European Medicines Agency. Linear calibration curves showed R 2 > 0.99 for glucose and lactate and the lower limit of quantification (LLOQ) was 12.5 mg/dL for both compounds. Spearman's ρ showed a strong, statistically significant correlation between the results obtained by the two labs ( P < 0.001; 0.836 for lactate, 0.963 for glucose). Bland–Altman plots were used to assess agreement between the measurements. For glucose, 11% of the analysed samples fell out of the 95% confidence interval; for lactate, only 9%. Deviant samples were re-analysed with the new method, yielding the same results, suggesting the possibility of deviant results by the spectrophotometric method. For lactate, the results of the developed method tended to show a small positive bias compared to those of the clinical lab. The established LLOQ was well below the postmortem cut-off values for determining hypoglycaemia and the measured glucose and lactate concentrations in most authentic samples. Results for the authentic samples showed good agreement between both methods and for both analytes. The developed and validated GC-MS based method has shown to be suitable for accurate measurement of glucose and lactate concentrations in vitreous humor.

FORMATION OF FUNCTIONAL ORIENTATION OF THE PREPARATION OF HIGH-CLASS ROWERS FOR MAJOR COMPETITIONS

Introduction. The reserve for increasing the functional support of the special working capacity of rowers is the search for new opportunities for the regulation and stimulation of functions that ensure the speed of deployment and the achievement of reaction limits, the stable development of functions in the process of increasing and compensating fatigue. Matherial and methods: gas analysis, measurement of blood lactate concentration, ergometry (Concept «ErgRowing»). Factor and correlational statistical analysis. Results: Three factors are singled out, which together form a specialized focus of special physical training. The share of the first factor in the total variance was 34.8%, the second – 18.0%, the third – 14.1%. The first factor includes the characteristics of the power of aerobic energy supply and the reaction of the cardiorespiratory system to the development of acidosis at the beginning of the distance and during the steady state period. The second factor is based on the assessment of the stimulation-influenced degree of lactic acidosis, at which the athlete reached the maximum consumption of O2. The third factor is based on the assessment of the anaerobic reserve in the second half of the distance, its role in the formation of excess (buffer) CO2, its compensation (EqVCO2) in the conditions of fatigue development. Conclusions. The necessity of using modes of training loads aimed at stimulation of neurodynamic functions of the body, implementation of "acute" hypoxia, simulation of physiological states associated with varying degrees of influence of hypoxia, hypercapnia, lactic acidosis is substantiated. Special modes can be used during warm-up, additional (to the main classes) training sessions during the daily training cycle.

SPECIFIC CHARACTERISTICS OF FUNCTIONAL ENSURING OF FOOTBALL PLAYERS’ SPECIAL WORKING CAPACITY AT THE STAGE OF SPECIALIZED BASIC TRAINING

Introduction. The improvement of the special training of U19 football players is based on the implementation of the conversion of general functional training into special structures for the functional support of the players' special working capacity. The general principles are based on the simulation of test modes and corresponding training loads. which correspond to the tempo-rhythmic structure of the athletes' competitive activity. Goal. To determine the characteristics of the functional training of football players of the age category U19 (18-19 years old). Methods. Gas analysis, measurement of blood lactate concentration, CRS &amp; IE test. 18 players aged 18-19 took part in the study. The results. The characteristics of the functional support of the special working capacity of the players of the main team had the corresponding characteristics – x ̅, quartile 75%, the maximum value: in the first series, EqPaCO2 – 2,03, 2,15, 2,26; VO2 – 49,4, 51,6, 54,1 (ml·min-1·kg-1); La – 9,4, 10,8, 11,0 (mmol·l-1); in the second series – EqVCO2 – 34,4, 36,9, 37,3, EqVO2 – 33,1, 35,2, 36,2;, VO2 – 56,1, 58,9, 60,1 (ml·min-1·kg-1), La– 16,8, 17,5, 18,9 (mmol·l-1). Conclusions. The characteristics of EqPaCO2, VO2, La registered as a result of the first series had differences between athletes of group "A" (players of the main team) and group "B" (players of the backup team), respectively - 3.4%, 5.3%, 4.3%. Characteristics EqVCO2, EqVO2, VO2, La registered as a result of the second series – 9,9%, 2,1%, 11,9%, 22,0% (p&lt;0,05). The indicators of the "training impulse" of the players of group "A", respectively, of the players of group "B" are significantly higher in the first series by 10,5%, in the second - by 16,7%. This indicates a reduced level of physiological stress of the main team players.

Comprehensive Evaluation and Determinant of Second Lactate Threshold in Homozygous Sickle Cell Disease

Following respiratory, cardiac and peripheral vascular impairments, Sickle Cell Disease (SCD) patients can experience early second lactate threshold (S2) during low intensity exercise. Through a comprehensive evaluation of exercise parameters we want to assess and find factors associated with an early reached of S2. Homozygous SCD patients were prospectively included in this study. They performed physical exercise with a standardized protocol. Gaz exchange, capillary lactate concentration measurements and echocardiography were performed at baseline and throughout the exercise until S2 was reached. Baseline and exercise data of the bottom and top half of patients in terms of %predicted VO2 at S2 were compared to investigate the determinant of an early S2, adjusted over age, sex and body mass index (BMI). Thirty patients were included (42 ± 12 years old, 50% of female). Bottom half group reached 34,5% ± 5,2 predicted VO2 at S2 (mean %predicted Watt = 32% ± 5,9) while top half group reached 46,2% ± 6,8 predicted VO2 at S2 (mean %predicted Watt = 42,8% ± 9,6) ( Fig. 1 ). Plasmatic hemoglobin concentration was the only baseline parameter associated with a lower %predicted VO2 at S2 (8.1 ± 1 vs. 9.2 ± 1 g/dl, P = 0.007). None of the baseline echocardiographic parameters were associated with a lower %predicted VO2 at S2. Diastolic adaptation through exercise was associated with a better power and VO2 at S2 (ratio S2/baseline of E’lateral wave and E/E’, respectively 1,39 vs. 1,63, P = 0,039 and 1,2 vs. 0,99, P = 0,004) SCD patients with lower hemoglobin and impaired diastolic adaptation through exercise displayed earlier S2, independently of age, sex and BMI. This highlights the great vulnerability of these patients to low metabolic stress. They should benefit from low intensity physical therapy programs.

Measurement of Myocardial Lactate Production for Diagnosis of Coronary Microvascular Spasm.

In about a quarter of patients with angina and non-obstructive coronary arteries, no epicardial spasm is noted on coronary arteriography during an angina attack. Since the pressure-rate product is almost identical at rest and the onset of attack in those patients, the decrease in coronary blood flow rather than increased myocardial oxygen consumption is likely to explain myocardial ischemia, indicating a substantial involvement with coronary microvascular spasm (MVS). Myocardial lactate production, which could be defined as a negative myocardial lactate extraction ratio (ratio of the coronary arterial-venous difference in lactate concentration to arterial concentration), is considered indicative of objective evidence to support the emerging myocardial ischemia. Thus, monitoring of the myocardial lactate production and the emergence of chest pain and ischemic electrocardiographic changes during acetylcholine (ACh) provocation testing is of significant value for detecting the entity of MVS. Practically, 1 min after incremental doses of ACh (20, 50, and 100 μg) are administered into the left coronary artery (LCA), paired samples of 1 mL of blood are collected from the LCA ostium and coronary sinus for measurement of lactate concentration by a calibrated automatic lactate analyzer. Then, the development of MVS could be confirmed by negative myocardial lactate extraction ratio despite the absence of angiographically demonstrable epicardial coronary spasm or before its occurrence throughout ACh provocation testing. In conclusion, assessment of myocardial lactate production is essential and valuable for the diagnosis of MVS.