Blood Lactate Concentration Research Articles

Shuttle Running Within a Small-Sided Game: Effects on Internal and External Workloads, in Young Elite Soccer Players.

To compare the effects of 2 small-sided games (SSGs), shuttle running within the bout (SSG-S) versus possession play only (SSG-P) on acute physiological and metabolic responses, perception of effort, and performance. Ten young elite male soccer players (age 18.6 [1.9]y) performed two 5vs5 SSG formats (SSG-S and SSG-P) consisting of 4 × 4minutes with 1minute of passive recovery between bouts, 2 times each, once a week, and in a randomized order. Heart rate, blood lactate concentration, and rating of perceived exertion were assessed as indices of internal workload. Total and relative distances, distance at moderate and high speed, distances traveled in accelerations (≥2m·s-2) and decelerations (≤-2m·s-2; DDEC), and average metabolic power were chosen as indices of external workload and collected with a 10-Hz portable global positioning system device. Total distance, distances traveled in acceleration, distances traveled in deceleration, average metabolic power (always P < .01 and g > 1.62-large effect), and distance at moderate speed (P = .03 and g = 0.84-large effect) were significantly higher in SSG-S than in SSG-P. Moreover, the SSG-S showed higher blood lactate concentration (P = .0001, g = 12.58-large effect) and rating of perceived exertion (P = .03, g = 1.14-large effect) values than SSG-P. No significant differences in peak heart rate, relative distance, and distance at high speed were found. Our study showed, in young competitive male soccer players, the effectiveness of an SSG format that includes shuttle running within each bout in the development of more relevant internal and external workloads. These experimental data should encourage coaches to use this new SSG regimen within the traditional weekly training program.

Accuracy of the 20-m shuttle run test for individualizing exercise intensity of high-intensity interval training

The aim of the study was to investigate the accuracy of the 20 m shuttle run test (20mSRT) for the prescription of high-intensity interval training (HIIT) and to examine the appropriate intensity, prescribed by the 20mSRT end-test speed, for the execution of HIIT. Twenty physical education students (age: 22.4 ± 0.8 years, body height: 175.7 ± 8.9 cm, body weight: 73.8 ± 13.4 kg) participated in the study. On two separate occasions the participants were first tested with a maximal incremental exercise test and the 20mSRT. On another two occasions they were required to perform a 10-minute HIIT session comprised of 15-s runs interspersed with 15-s passive recovery. The intensities of the HIIT sessions were either 100% (T100%) or 110% (T110%) of the end-test speed reached in the 20mSRT. Mean oxygen uptake (VO2) (84.4 ± 5.5% vs 77.8 ± 6.9% of VO2max), mean heart rate (HR) (93 ± 2.8% vs 87.6 ± 4.6% of HRmax), blood lactate concentration (12.6 ± 2.1 vs 5.4 ± 2.6 mmol/l), and ratings of perceived exertion (9.5 ± 0.5 vs 6.7 ± 1) were all significantly (p&amp;lt;.01) higher during T110% vs T100%. The percentage of the total exercise time spent ≥ 90% VO2max (37.6 ± 25.3 vs 18.6 ± 18.0%, p&amp;lt;.05) and ≥ 90% HRmax (73.9 ± 17.7% vs 37.5 ± 33.3, p&amp;lt;.001) were also significantly higher during T110%. The mean VO2 and HR coefficient of variation during T110% were 6.5 and 3%, respectively. The cardiorespiratory, metabolic, and perceptual responses to T110% were reflective of the responses typical for HIIT, while T100% induced insufficient physiological stress to enable optimal cardiorespiratory adaptation. Therefore, the intensity of 110% 20mSRT is preferable for inducing the appropriate acute physiological responses and the 20mSRT can be used to accurately prescribe HIIT.

Changes in Lactate-related Fecal Microbiome in Hyperlactatemia Diabetic Dogs.

The correlation between the intestinal microbiome and endocrine disorders has recently been drawing attention as an important key for determining their pathology and clinical assessment. In this study, we evaluated the microbiome of dogs with insulin-dependent diabetes mellitus (IDDM) with respect to blood lactate. Fecal samples were obtained from 17 subjects and real-time quantitative polymerase chain reaction determinations were performed to quantify the gene expression levels of lactate-producing and dysbiosis index-related bacteria. Expression levels of the lactate-producing bacteria Lactobacillus spp., Enterococcus spp., and Bifidobacterium spp., were confirmed in patients with high concentrations of lactate in the blood. The abundance of Enterococcus and Bifidobacterium was higher in diabetic dogs compared to that of non-diabetic dogs. When blood lactate concentrations were high, the abundance of Bifidobacterium also increased. Blood lactate levels influence the gut microbiome in dogs with IDDM. This study will help understand the gut microbiota in the context of diabetes in human and veterinary medicine.

200m breaststroke post-competition blood lactate removal characteristics

The goal of this study was to define the individual model characteristics of lactic acid removal after 200m breaststroke competitive load in a female swimmer in relation to different pool lengths (25m vs. 50m). The second goal was methodological and referred to the presentation of newly applied metrological procedures for the Individual Lactate Recovery Profile modeling. Six races from the competitive season 2021/22 were selected, in which the athlete achieved the most valuable results in relation to the FINA score. To establish the metabolic response of the organism to the competition effort, the method of determining the level of lactate concentration in capillary blood (La in mmol/L) was used. Differences between the mean values of variables were established using ANOVA. The polynomial curve equation function was used to create a blood lactate concentration in a function of recovery time model (La-trecovery). The ANOVA showed that there was no statistically significant difference between the monitored variables and the pool length function (p=.097). The maximum achieved blood lactate concentration in the acute race recovery phase was 13.17 ± 2.81 and 12.08 ± 1.80 mmol/L and the given concentration initially occurred in the time of 240.0 ± 85.6 s and 169.3 ± 79.9 s in the 25 and 50m pool, respectively. In relation to the time of complete passive recovery required to establish acidosis at the level of 2 mmol/L (25 and 50m pool) occurred in 1191.7 ± 481.3 s and 1326.7 ± 405.1 s, while the full index of intensity of blood lactate clearance was 135.7 ± 60.7 s/mmol/L and 124.0 ± 60.7 s/mmol/L for 25m and 50m pool, respectively. Although no statistically significant difference was found between the parameters of recovery in relation to pool length, the offered mathematical models enabled a practical individual approach to controlling the specific adaptation to training for achieving a higher competitive level performance.

A fresh look at sports PSM-systems

Abstract The aim of the proposed study is to reveal the correlations between the dynamics of Respiratory Rate (RR) and Heart Rate (HR) during intermittent physical work at maximum power on a cycle ergometer. The stage of investigating the General functional athlete readiness (GFAR) was conducted using the sports standard “R-Engine” and the cycle ergometer in 16 volunteers (10 men, 6 women) whose average age was 21±1.17 years. To determine the athletic potential of the volunteers in this study, we used our own Coefficient of Anaerobic Capacity (CANAC Q, beats). Continuous registration of the heart rate and respiratory rate of volunteers in the maximum power sports test was performed by the “RheoCardioMonitor” system with a module of the athlete functional readiness based on the method of Transthoracic electrical impedance rheography (TEIRG). The degree of correlation of functional indicators (M, HRM, GFAR) with CANAC Q in all experimental series of the study group as a whole (n=80) was at a very high level, which confirmed the effectiveness of using the Coefficient of Anaerobic Capacity (CANAC Q) in assessing the general functional athlete readiness of the volunteers. CANAC Q is measured in “beats” of the heart and is recorded very accurately using the method of transthoracic electrical impedance rheography (TEIRG). For this reason, as a promising sports PSM-system, CANAC Q can replace the methods for determining the functional athlete readiness by blood lactate concentration and maximum oxygen consumption.

ANÁLISE DE ESTRATÉGIAS ALTERNATIVAS PARA RECUPERAÇÃO FÍSICA E FORÇA MUSCULAR APÓS O TREINO DE BASQUETEBOL

ABSTRACT Introduction: The need to increase muscle strength and optimize physical recovery is essential for athletes’ maximum performance in basketball competitions. However, alternative interventions are still little explored for the physical recovery process. Objective: Explore the effect of muscle strength training in basketball and alternative strategies for physical recovery. Methods: After basketball strength training, the control group adopted the traditional stretching method, while the experimental group combined yoga and music for a gradual warm-up and body relaxation. In this process, we measured changes in blood lactate content during exercise. Within 5 minutes, 15 minutes, and 30 minutes after exercise was used to analyze the effect of muscle recovery between the groups. Results: Muscle strength training can comprehensively improve performance indicators of all aspects of basketball. Still, many biochemical parameters of muscle strength, especially of the shoulder and back, showed no significant effect in the control group. The relative total work (TWP), average power (AP), and relative average power (APP) indicators showed a significant impact after the alternative intervention in the experimental group. Conclusion: Muscle strength training can effectively improve multiple qualities in athletes, providing gains in strength development and motor skills with an acceleration in the physical recovery stage. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

A functional evaluation of anti-fatigue and exercise performance improvement following vitamin B complex supplementation in healthy humans, a randomized double-blind trial.

B vitamins play a crucial role in maintaining fundamental cellular functions and various essential metabolic pathways in the body. Although they do not directly provide energy, each B vitamin acts as a cofactor in energy metabolism processes. Based on the evidence presented above, we hypothesized that a 28-day supplementation of vitamin B would enhance physical performance and reduce physical fatigue. The objective of this study was to evaluate the anti-fatigue effect of vitamin B supplementation, specifically vitamin B1, B2, B6, and B12, and its potential to improve exercise performance. We employed a randomized double-blind crossover design with a 28-day supplementation period. Sixteen male and sixteen female subjects, aged 20-30 years, were divided into two groups: the placebo group (n=16, equal gender distribution) and the Ex PLUS® group (n=16, equal gender distribution). The participants received either placebo or Ex PLUS® (one tablet per day) for 28 consecutive days. Following the intervention, there was a 14-day wash-out period during which the subjects did not receive any further interventions. After supplementation with Ex PLUS®, we found a significant increase in the running time by 1.26-fold (p < 0.05) to exhaustion compared to that before supplementation and that in the placebo group. In addition, the Ex PLUS® supplementation group presented significantly reduced blood lactate and blood ammonia concentrations during exercise and at rest after exercise compared with placebo (p < 0.05). In conclusion, 28 consecutive days of vitamin B complex (Ex PLUS®) supplementation significantly improved exercise endurance performance and reduced exercise fatigue biochemical metabolites in not athletes. In addition, it does not cause adverse effects in humans when taken at appropriate doses.

A total closed chest swine model of acute myocardial infarction-related cardiogenic shock: A critical double coronary sub-occlusion approach

The management of acute myocardial infarction-related cardiogenic shock (AMICS) represents a significant challenge, with mortality rates remaining high (40–60%), despite recent advances. Current animal models of myocardial infarction are either associated with a very high rate of per-procedure malignant arrhythmia, or with very low impairment of hemodynamic parameters, or with the inability to have complete coronary reperfusion. We sought to develop a closed chest and clinically relevant large animal model of severe AMICS, with high survival rate. Adult pigs were anaesthetized and mechanically ventilated. Percutaneous cardiac catheterization was performed under fluoroscopy. Advanced left ventricular dysfunction was induced by 120 minutes of critical sub-occlusion of the proximal left anterior descending coronary artery and the mid circumflex artery. A thorough hemodynamic assessment was obtained by invasive and non-invasive monitoring devices. Repeated blood samples were obtained to determine blood gas parameters, lactate, and haemoglobin concentration. After death, the heart was retrieved for further histological analyses. All animals (n = 12) developed significant circulatory failure associated with AMICS upon reperfusion and beyond. No animal died during the ischemia process. However, all animals that did not benefited from vasopressor support (“sham” group, n = 4) spontaneously died within 30 minutes of reperfusion, confirming the severity of the model. Cardiogenic shock was characterized by a drop in mean arterial pressure below 60 mmHg (58 ± 5 mmHg at 120 min of ischemia), a significant decrease in mean cardiac output (−44% from 5.7 ± 0.4 at baseline to 3.2 ± 0.4 at 120 minutes of ischemia) and SvO2 (−32% from 57 ± 8 at baseline to 39 ± 6 at 120 minutes of ischemia) and a significant increase in left ventricle end-diastolic pressure (LVEDP) (+110% from 10 ± 3 at baseline to 21 ± 3 at 120 minutes of ischemia). CO2 gap and coronary sinus venous oxygen saturation increased significantly upon ischemia and reperfusion and remained elevated throughout (P ≤ 0.001 for all comparisons). Myocardial samples corroborated extensive cellular necrosis and inflammatory infiltrates. We present, for the first time, a stable and clinically relevant model of severe AMICS obtained by critical double coronary sub-occlusion. The greater severity of the model did not lead to an increase in the frequency of malignant arrythmias and per-procedure mortality.

Ruminal microbiome and blood parameters in beef cattle fed with high-grain diets buffered with Lithothamnium calcareum

Context and aims DNA metabarcoding strategy was used to sequence the 16S rRNA region of ruminal fluid samples from Nellore cattle fed with concentrate-rich diets in response to modulatory effect of buffering additives calcarea seaweed (Lithothamnium calcareum) and sodium bicarbonate. Methods Besides characterising the richness and diversity indices of rumen bacterial community, the impact of potentially acidogenic diets on rumen pH, blood parameters, and short-chain fatty acid profile (SCFA) was investigated for which four male Nellore cattle were used, distributed in a 4 × 4 Latin square (treatments × periods). Treatments comprised the same highly concentrated basal diet, and were as follows: T1, without additive (CON); T2, inclusion of 90 g of sodium bicarbonate (BIC); T3, inclusion of 90 g of L. calcareum (L90); and T4, inclusion of 45 g of L. calcareum (L45). Data were analysed in R, in which diversity and abundance at gender level were analysed using Friedman’s test, with means being adjusted by False Discovery Rate (FDR) correction. The analyses of pH, biochemical parameters and SCFA were analysed using Scott–Knott test and means were evaluated with a significance level of 10% (P &lt; 0.10). Key results We identified 1474 operational taxonomic units (OTUs) belonging to 52 genera and 16 phyla of bacteria domain. The results showed that bacterial microbiota were dominated by Firmicutes (44.12%), Bacteroidetes (28.29%), and Proteobacteria (5.88%). Animals fed with L90 demonstrated greater abundance and ruminal diversity for the Prevotella genus (P &lt; 0.07% and P &lt; 0.09% respectively), whereas cattle supplemented with L45 demonstrated greater diversity of the Fibrobacter genus (P &lt; 0.05). There were differences in molar proportion for acetic (P &lt; 0.07%) and valeric (P &lt; 0.03%) acids in the period before feeding. Higher blood lactate concentrations were observed in animals supplemented with L45 (P &lt; 0.06%), while animals that received treatments L90 and BIC presented lower levels of blood lactate. This metabolite was lower in animals fed with 90 g of sodium bicarbonate and L. calcareum daily. These treatments also reduced the concentration of acetic acid and increased that of valeric acid, and improved ruminal diversity. Conclusions and implications Our results supported this choice to improve ruminal function, with a great prospective of better weight-gain performance in Nellore cattle.

Predictive value of Pv-aCO2/Ca-vO2 combined blood lactate concentration for primary peritonitis-related septic shock in children

To investigate the prognostic value of the ratio of veno-arterial carbon dioxide partial pressure difference to arterio-venous oxygen content difference (Pv-aCO2/Ca-vO2) in children with primary peritonitis-related septic shock. A retrospective study was conducted. Sixty-three children with primary peritonitis-related septic shock admitted to department of intensive care unit of the Children's Hospital Affiliated to Xi'an Jiaotong University from December 2016 to December 2021 were enrolled. The 28-day all-cause mortality was the primary endpoint event. The children were divided into survival group and death group according to the prognosis. The baseline data, blood gas analysis, blood routine, coagulation, inflammatory status, critical score and other related clinical data of the two groups were statistics. The factors affecting the prognosis were analyzed by binary Logistic regression, and the predictability of risk factors were tested by the receiver operator characteristic curve (ROC curve). The risk factors were stratified according to the cut-off, Kaplan-Meier survival curve analysis compared the prognostic differences between the groups. A total of 63 children were enrolled, including 30 males and 33 females, the average age (5.6±4.0) years old, 16 cases died in 28 days, with mortality was 25.4%. There were no significant differences in gender, age, body weight and pathogen distribution between the two groups. The proportion of mechanical ventilation, surgical intervention, vasoactive drug application, and procalcitonin, C-reactive protein, activated partial thromboplastin time, serum lactate (Lac), Pv-aCO2/Ca-vO2, pediatric sequential organ failure assessment, pediatric risk of mortality III in the death group were higher than those in the survival group. Platelet count, fibrinogen, mean arterial pressure were lower than those in the survival group, and the differences were statistically significant. Binary Logistic regression analysis showed that Lac and Pv-aCO2/Ca-vO2 were independent risk factors affecting the prognosis of children [odds ratio (OR) and 95% confidence interval (95%CI) were 2.01 (1.15-3.21), 2.37 (1.41-3.22), respectively, both P < 0.01]. ROC curve analysis showed that the area under curve (AUC) of Lac, Pv-aCO2/Ca-vO2 and their combination were 0.745, 0.876 and 0.923, the sensitivity were 75%, 85% and 88%, and the specificity were 71%, 87% and 91%, respectively. Risk factors were stratified according to cut-off, and Kaplan-Meier survival curve analysis showed that the 28-day cumulative probability of survival of Lac ≥ 4 mmol/L group was lower than that in Lac < 4 mmol/L group [64.29% (18/28) vs. 82.86% (29/35), P < 0.05]. Pv-aCO2/Ca-vO2 ≥ 1.6 group 28-day cumulative probability of survival was less than Pv-aCO2/Ca-vO2 < 1.6 group [62.07% (18/29) vs. 85.29% (29/34), P < 0.01]. After a hierarchical combination of the two sets of indicator variables, the 28-day cumulative probability of survival of Pv-aCO2/Ca-vO2 ≥ 1.6 and Lac ≥ 4 mmol/L group significantly lower than that of the other three groups (Log-rank test, χ2 = 7.910, P = 0.017). Pv-aCO2/Ca-vO2 combined with Lac has a good predictive value for the prognosis of children with peritonitis-related septic shock.

OCE-205 in rats and non-human primates: Pharmacokinetic and pharmacodynamic analysis

Treatment for complications associated with the hemodynamic consequences of decompensated cirrhosis remains suboptimal. Terlipressin, the latest pharmacological management of hepatorenal syndrome–acute kidney injury (HRS-AKI), targets the vasopressin system but has serious side effects. OCE-205 is a novel peptide designed to target the vasopressin receptor system as a mixed V1a agonist/antagonist, resulting in effective partial agonism without V2 agonism. We examined the in vivo pharmacokinetic/pharmacodynamic properties of OCE-205 in healthy rats and cynomolgus monkeys. OCE-205 was administered by IV or SC bolus injection; arginine vasopressin (AVP) or terlipressin were comparators. After IV OCE-205 administration in rats, mean plasma concentration decreased in a mostly linear manner to 2 mg/mL after 120 min, and for SC administration, slowly decreased to ∼50 ng/mL after 300 min. Compared with pre-test values, arterial blood pressure values significantly increased after all OCE-205 doses tested. For monkeys, the concentration after IV OCE-205 administration was mostly linear to 5 ng/mL after 180 min, and for SC administration, ∼3 ng/mL after 480 min. Subcutaneous OCE-205 administration increased mean arterial pressure (MAP) versus baseline, with ΔMAP in OCE-205–treated animals marked and long-lasting while terlipressin induced an increase from baseline in MAP, with negligible ΔMAP, on average, by 150 min after administration in all groups. AVP, but not OCE-205, significantly increased blood lactate concentrations. OCE-205 was well tolerated in adult male rats and cynomolgus monkeys following single-dose bolus administration. The preclinical results of OCE-205, with its demonstrated V1a selective partial agonist activity and potentially tolerable safety profile, suggest its potential utility for treatment of the cardiovascular complications of cirrhosis. Institutional protocol numberProcedures were approved by the Ferring Research Institute (FRI) Institutional Animal Care and Use Committee (IACUC) on November 27, 2006 under protocol FRI 06-011, and by the Sinclair Research Center IACUC under protocol S11177.

The short-term recovery of sprint cycling performance

Short-term sprint cycling performance recovery was investigated, with consideration to the Match Sprint. Fifteen strength-trained men (age: 24 ± 6 years; height: 1.81 ± 0.08 m; body mass: 83.4 ± 8.4 kg) were first familiarised with an 18 s sprint. During the baseline trial, blood lactate concentration, tissue saturation index, and oxygen uptake were monitored following a single sprint. In the remaining trials, the recovery duration (45, 90, 135, 180, 360, and 720 s) between two sprints was varied. Peak (PPO) and mean (MPO) power output were computed for each sprint. The recovery percentage of MPO and the recovery time-course of the physiological variables were modelled using one- and two-phase exponential functions. Statistical significance was set a priori at p &lt; 0.05. Effects of sprint number, recovery time, and a sprint number × recovery time interaction were found for both PPO and MPO. Post hoc tests revealed significant differences between sprints at all time-points for both variables. The time constant (τ), 130.6 ± 95.6 s, of the one-phase exponential function (asymptotic amplitude [A0] = 97.4 ± 2.5%), suggested that performance recovery had stabilised within 12 minutes. However, the parameters of the two-phase function indicated that recovery was incomplete (A0 = 87.7 ± 6.4%, A1 = 11.9 ± 5.2%, τ0 = 56.3 ± 33.3 s, τ1 = 458.2 ± 283.3 s). The τ for MPO recovery was not significantly correlated with any of the physiological variables. The reduction in sprint cycling performance throughout the tested time-period could be meaningful for athletes competing in the Match Sprint.

Frequency of blood lactate elevation following esophagectomy and its association to postoperative complications.

Esophagectomy is a major surgical intervention and a cornerstone in the treatment of esophageal cancer. There is clinical experience that blood lactate concentration often is elevated in the period following esophagectomy, but the incidence and clinical consequences are sparsely studied. We extracted data from all patients undergoing esophagectomy at Karolinska University Hospital 2016-2018, n= 153. Most were performed with minimally invasive technique, n= 130. Blood lactate values directly after surgery, highest value during the first night, and morning level on postoperative day one were recorded. Primary outcome was hospital length of stay and secondary outcome was a composite of postoperative infection, additional surgery, or intensive care during the hospital stay. Development of anastomotic leak was analyzed separately. Postoperative hyperlactatemia was common as 93% of patients had peak lactate concentration >1.6 mmol/L and 27% >3.5 mmol/L in the first night following operation. Median hospital length of stay was 14 days. Blood lactate showed a weak correlation to hospital stay and intensive care the morning following surgery, but not at arrival to postoperative ward. There were no statistical differences between those with and without anastomotic leak at any of the time points. Elevated lactate in the first 12-16 h postoperatively was related to surgical factors (open technique, surgery time, and perioperative bleeding) but not to patient related factors (ASA-class, Charlson comorbidity index, sex, age) or cumulative fluid balance. In conclusion, elevated blood lactate in the immediate time following esophagectomy showed a weak association to intensive care and length of stay but not anastomotic leak.

Post-stress physioprophylaxis test in soccer players: effects of blood lactate concentrations

Objective: To determine the effects of physioprophylaxis (PP) on blood lactate (BL) concentrations after maximal incremental stress test, considering that this is the application of techniques in sports physiotherapy to reduce signs of muscle fatigue that can trigger injuries due to overload. Materials and Methods: Quantitative study, experimental type, longitudinal section in 12 university players. The group is divided into one control group (CG) with recovery at rest without PP and another experimental group (EG) to which PP is applied at the end of the test. Blood lactate is recorded with Accutrend Plus at the beginning of the test, (1) five minutes after finishing the test (2) and after the PP (3) at two different moments for intra-subject analysis. Results: The following data were obtained regarding blood lactate clearance, Moment 1: Without Plan (WoP) 4.86±1.4 and With Plan (WP) 8.85±1.25 (p&lt;0.05), moment 2: (WoP) 5.6±1.76 and (WP) 7.8±1.3 (p&lt;0.05) in mmol/L, and intra-subject: (WoP): 5.25±1.58; (WP): 8.35±1.33 (p&lt;0.05). Conclusions: The clearance of lactate in the blood at 30 minutes post stress test in the EG is bigger than the CG, because they recovered with the physioprophylactic plan.

Closed Bipolar Electrode-Enabled Electrochromic Sensing of Multiple Metabolites in Whole Blood.

We report a closed bipolar electrode (CBE)-based sensing platform for the detection of diagnostic metabolites in undiluted whole human blood. The sensor is enabled by electrode chemistry based on: (1) a mixed layer of blood-compatible adsorption-resistant phosphorylcholine (PPC) and phenylbutyric acid (PBA), (2) ferrocene (Fc) redox mediators, and (3) immobilized redox-active enzymes. This scheme is designed to overcome nonspecific protein adsorption and amplify sensing currents in whole human fluids. The scheme also incorporates a diffusing mediator to increase electronic communication between the immobilized redox enzyme and the working electrode. The use of both bound and freely diffusing mediators is synergistic in producing the electrochemical response. The sensor is realized by linking the analyte cell, containing the specific electrode surface architecture, through a CBE to a reporter cell containing the electrochromic reporter, methyl viologen (MV). The colorless-to-purple color change accompanying the 1e- reduction of MV2+ is captured using a smartphone camera. Subsequent red-green-blue analysis is performed on the acquired images to determine cholesterol, glucose, and lactate concentrations in whole blood. The CBE blood metabolite sensor produces a linear color change at clinically relevant concentration ranges for all metabolites with good reproducibility (∼5% or better) and with limits of detection of 79 μM for cholesterol, 59 μM for glucose, and 86 μM for lactate. Finally, metabolite concentration measurements from the CBE blood metabolite sensor are compared with results from commercially available FDA-approved blood cholesterol, glucose, and lactate meters, with an average difference of ∼3.5% across all three metabolites in the ranges studied.

Cardiorespiratory, Metabolic, and Performance Changes from the Effects of Creatine and Caffeine Supplementations in Glucose-Electrolyte-Based Sports Drinks: A Double-Blind, Placebo-Controlled Study.

The purpose of this study is to investigate the additive effects of creatine and caffeine on changes in the cardiorespiratory system, metabolism, and performance of soccer players. Seventeen male soccer players randomly ingested three sports drinks comprising the following: glucose−electrolyte-based (Drink 1, control; D1), glucose−electrolyte-based drink + 5 g creatine (Drink 2; D2), and glucose−electrolyte-based drink + 5 g creatine + 35 mg caffeine (Drink 3; D3) during a 15 min recovery period after the modified Loughborough Intermittent Shuttle Test (LIST) on a standard outdoor soccer field. Then, a 20-m repeated intermittent sprinting activity was performed. The results showed no significant differences in cardiorespiratory and gas exchange variables. The non-significant levels of blood glucose concentrations among drinks with higher blood lactate concentrations were detected in parallel with increased heart rate during intermittent sprinting as a result of exercise intensities. Significantly longer sprinting time was found in D3 than D1 (p < 0.05), with no significant differences between D2 and D3. From this study, we conclude that the additive effect of caffeine−creatine supplements in a glucose−electrolyte drink during the 15 min recovery period enhances repeated 20-m high-intensity running in soccer players with no negative effect on cardiorespiratory functions.

The Influence of Nutrition and Physical Activity on Exercise Performance after Mild COVID-19 Infection in Endurance Athletes-CESAR Study.

COVID-19 and imposed restrictions are linked with numerous health consequences, especially among endurance athletes (EA). Unfavorable changes in physical activity and nutrition may affect later sports and competition performance. The aims of this study were: (1) to assess the impact of COVID-19 infection and pandemic restrictions on the nutrition and physical activity of EAs and (2) to compare them with the results of cardiopulmonary exercise testing (CPET). In total, 49 EAs (nmale = 43, nfemale = 6, mean age = 39.9 ± 7.8 year., height = 178.4 ± 6.8 cm, weight = 76.3 ± 10.4 kg; BMI = 24.0 ± 2.6 kg·m-2) underwent pre- and post-COVID-19 CPET and fulfilled the dietary and physical activity survey. COVID-19 infection significantly deteriorated CPET performance. There was a reduction in oxygen uptake and in heart rate post-COVID-19 (both p &lt; 0.001). Consuming processed meat and replacing meat with plant-based protein affected blood lactate concentration (p = 0.035). Fat-free mass was linked with consuming unsaturated fatty acids (p = 0.031). Adding salt to meals influenced maximal speed/power (p = 0.024) and breathing frequency (p = 0.033). Dietary and Fitness Practitioners and Medical Professionals should be aware of possible COVID-19 infection and pandemic consequences among EA. The results of this study are a helpful guideline to properly adjust the treatment, nutrition, and training of EA.

COVID-19 and athletes: Endurance sport and activity resilience study-CAESAR study.

Background: The COVID-19 pandemic and imposed restrictions influenced athletic societies, although current knowledge about mild COVID-19 consequences on cardiopulmonary and physiologic parameters remains inconclusive. This study aimed to assess the impact of mild COVID-19 inflection on cardiopulmonary exercise test (CPET) performance among endurance athletes (EA) with varied fitness level. Materials and Methods: 49 EA (nmale = 43, nfemale = 6, mean age = 39.94 ± 7.80yr, height = 178.45cm, weight = 76.62kg; BMI = 24.03kgm-2) underwent double treadmill or cycle ergometer CPET and body analysis (BA) pre- and post-mild COVID-19 infection. Mild infection was defined as: (1) without hospitalization and (2) without prolonged health complications lasting for >14days. Speed, power, heart rate (HR), oxygen uptake (VO2), pulmonary ventilation, blood lactate concentration (at the anaerobic threshold (AT)), respiratory compensation point (RCP), and maximum exertion were measured before and after COVID-19 infection. Pearson's and Spearman's r correlation coefficients and Student t-test were applied to assess relationship between physiologic or exercise variables and time. Results: The anthropometric measurements did not differ significantly before and after COVID-19. There was a significant reduction in VO2 at the AT and RCP (both p < 0.001). Pre-COVID-19 VO2 was 34.97 ± 6.43mlkg·min-1, 43.88 ± 7.31mlkg·min-1 and 47.81 ± 7.81mlkg·min-1 respectively for AT, RCP and maximal and post-COVID-19 VO2 was 32.35 ± 5.93mlkg·min-1, 40.49 ± 6.63mlkg·min-1 and 44.97 ± 7.00mlkg·min-1 respectively for AT, RCP and maximal. Differences of HR at AT (p < 0.001) and RCP (p < 0.001) was observed. The HR before infection was 145.08 ± 10.82bpm for AT and 168.78 ± 9.01bpm for RCP and HR after infection was 141.12 ± 9.99bpm for AT and 165.14 ± 9.74bpm for RCP. Time-adjusted measures showed significance for body fat (r = 0.46, p < 0.001), fat mass (r = 0.33, p = 0.020), cycling power at the AT (r = -0.29, p = 0.045), and HR at RCP (r = -0.30, p = 0.036). Conclusion: A mild COVID-19 infection resulted in a decrease in EA's CPET performance. The most significant changes were observed for VO2 and HR. Medical Professionals and Training Specialists should be aware of the consequences of a mild COVID-19 infection in order to recommend optimal therapeutic methods and properly adjust the intensity of training.

Constant Load Pedaling Exercise Combined with Electrical Muscle Stimulation Leads to an Early Increase in Sweat Lactate Levels.

A novel exercise modality combined with electrical muscle stimulation (EMS) has been reported to increase cardiovascular and metabolic responses, such as blood lactate concentration. We aimed to examine the effect of constant load pedaling exercise, combined with EMS, by non-invasively and continuously measuring sweat lactate levels. A total of 22 healthy young men (20.7 ± 0.8 years) performed a constant load pedaling exercise for 20 min at 125% of the pre-measured ventilatory work threshold with (EMS condition) and without (control condition) EMS stimulation. Blood lactate concentration was measured by blood samples obtained from the earlobe every minute. Sweat lactate was monitored in real time using a sensor placed on the forearm. The sweat lactate threshold (sLT) was defined as the point of increase in sweat lactate. sLT occurred significantly earlier in the EMS condition than in the control condition. In the single regression analysis, the difference in sLT between the two conditions, as the independent variable, was a significant predictor of the difference in blood lactate concentrations at the end of the exercise (p < 0.05, r = −0.52). Sweat lactate measurement may be a noninvasive and simple alternative to blood lactate measurement to determine the effectiveness of exercise combined with EMS.

Stiffness and thickness of the upper trapezius muscle increase after repeated climbing bouts in male climbers.

Indoor climbing involves overloading the shoulder girdle, including the rotator cuff and upper trapezius muscles. This on the field study aimed to investigate the effects of repeated climbing bouts on morphological and mechanical measures of the upper trapezius muscle. Fifteen experienced male climbers participated in the study. Rate of perceived exertion (RPE), blood lactate concentration ([La-]b), and stiffness and thickness over four points of the upper trapezius were assessed before and after a repeated climbing exercise. The procedure for the climbing exercise consisted of five climbs for a total time of 5-minutes per climb, followed by a 5-minute rest. The analysis showed an increase from baseline to after the 3rd climb (p≤0.01) for RPE and after the 5th climb for [La-]b (p≤0.001). Muscle stiffness and thickness increased at all points (1-2-3-4) after the 5th climb (p≤0.01). We found spatial heterogeneity in muscle stiffness and thickness; muscle stiffness was the highest at Point 4 (p≤0.01), while muscle thickness reached the highest values at points 1-2 (both p≤0.01). Moreover, the analysis between the dominant and non-dominant shoulder showed greater stiffness after the 1st climb at Point 1 (p=0.004) and after the 5th climb at Point 4 (p≤0.001). For muscle thickness, the analysis showed significant changes in time and location between the dominant and the non-dominant shoulder. Bilateral increases in upper trapezius muscle stiffness and thickness, with simultaneous increases in RPE and blood lactate in response to consecutive climbs eliciting fatigue.