Peak Lactate Concentration Research Articles

3-min All-out Test to Evaluate Aerobic and Anaerobic Indexes in Court Team Sports.

This study aimed to test the reproducibility of the 3-min all-out effort applied using shuttle running and compare its values to aerobic parameters. On the first day, 14 futsal players underwent an exhaustive test to determine the maximal incremental speed (MIS) and anaerobic threshold (AnT). On the second day, the participants performed the 3-min all-out effort (n=14), which was repeated after 48 h (third day) to test its reproducibility (n=11). Peak oxygen consumption (V̇ O2PEAK) and peak blood lactate concentrations ([La-]) were determined from 3-min all-out efforts performed through a 20-m shuttle run on the official court. The distance covered, mean speed, and critical speed (CS) during the 3-min all-out presented direct relationships with aerobic parameters determined through the incremental test (r>0.62). The distance covered above CS (D') presented a direct relationship with peak lactate concentrations induced by a 3-min all-out effort (r=0.81). Despite the acceptable levels of reproducibility observed for most of the 3-min all-out variables, the minimal detectable change for D' was high (72%). Our results demonstrated the potential use of mean speed to evaluate aerobic fitness. However, the applicability of the 3-min all-out shuttle run test to monitor training adaptations should be avoided, at least in nonexperienced athletes.

Reliability of the Maximal Lactate Accumulation Rate in Rowers.

The maximal lactate accumulation rate (VLamax) has been linked to lactic anaerobic performance. Hence, accurate and reliable assessment is crucial in sport-specific performance testing. Thus, between-day reliability data of rowing-specific VLamax assessment was examined. Seventeen trained rowers (eight females and nine males; 19.5±5.2 yrs; 1.76±0.08 m; 70.2±8.9 kg; V̇O2max: 54±13 ml/min/kg) performed 20-s sprint tests on two separate days (one week apart) on a rowing ergometer. VLamax, peak lactate concentration, time to peak lactate, and mean rowing power were measured. Good to excellent intraclass correlation coefficients (ICCs), low standard error of measurement (SEM), and acceptable levels of agreement (LoAs; 90% confidence interval) for VLamax (ICC=0.85; SEM=0.02 mmol/L/s; LoA±0.09 mmol/L/s), peak lactate (ICC=0.88; SEM=0.3 mmol/L; LoA±1.4 mmol/l), time to peak lactate (ICC=0.92; SEM=0.1 min; LoA±0.5 min), and mean rowing power (ICC=0.98; SEM=3 W; LoA±39 W) were observed. In addition, VLamax was highly correlated (r=0.96; p≤0.001) to rowing power. Thus, VLamax and sprint performance parameters can be measured highly reliably using this sport-specific sprint test in rowing.

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.

Association between dynamic upper airway obstructions and fitness parameters in Standardbred racehorses during high-speed treadmill exercise.

To evaluate the association between the severity of dynamic upper airway obstruction (DUAO) and selected fitness parameters in Standardbred racehorses measured by treadmill test. 191 Standardbred racehorses that underwent a standardized diagnostic protocol for poor performance evaluation between 2002 and 2021 at the Veterinary Teaching Hospital, University of Milan. Horses underwent a diagnostic protocol including clinical examination, lameness evaluation, laboratory analyses, ECG, resting upper airway endoscopy, metabolic incremental treadmill test, high-speed treadmill endoscopy, postexercise tracheobronchoscopy, and bronchoalveolar lavage fluid cytology. On the basis of findings of the high-speed treadmill endoscopy, horses were divided into the following groups: no DUAO, mild DUAO (medial deviation of the aryepiglottic folds or epiglottic entrapment), severe DUAO (dorsal displacement of the soft palate, nasopharyngeal collapse, dynamic laryngeal collapse, or epiglottic retroversion), and multiple DUAOs (different forms of DUAO occurring concomitantly). Fitness parameters, measured by incremental treadmill test, included speed at a heart rate of 200 bpm (V200), speed and heart rate at a lactate concentration of 4 mmol/L (VLa4, HRLa4), peak lactate, maximum speed, maximum hematocrit, and minimum pH. Data were compared between groups by use of descriptive and statistical analyses. Horses affected by severe or multiple DUAOs showed lower V200 and VLa4, compared to the no-DUAO group; horses with multiple DUAOs also had higher peak lactate concentrations compared to horses without DUAOs. While mild forms of DUAO do not affect athletic capacity, severe forms of DUAO and multiple DUAOs may lead to reduced fitness in Standardbred racehorses by impairing aerobic capacity.

Physiological Profiling and Energy System Contributions During Simulated Epée Matches in Elite Fencers.

The aim of this study was to investigate physiological responses and energetic contributions during simulated epée matches in elite fencers. Ten elite male fencers participated in simulated epée (direct elimination) matches. Simulated epée matches included 3 bouts of 3minutes each with 1-minute rests between bouts. During these sessions, physiological variables such as mean and peak heart rate, peak and mean oxygen uptake (VO2peak and VO2mean), metabolic equivalents of task in VO2peak and VO2mean, and blood lactate concentrations (peak lactate concentration and delta blood lactate concentration) were measured. Furthermore, energetic contributions (oxidative [WOxi], glycolytic, and phosphagen) and time-motion variables were estimated. Values of peak heart rate, mean heart rate, and WOxi (in percentages) were significantly higher in the second and third bouts compared with the first. VO2peak and metabolic equivalents of task in VO2peak were significantly higher in the first bout compared with the third bout. Values of delta blood lactate concentration and glycolytic contribution (in kilojoules and percentages) were significantly lower in the second and third bouts compared with the first. VO2mean and metabolic equivalents of task in VO2mean were significantly higher in the second bout compared with the third bout. Furthermore, WOxi (in kilojoules and percentage) was significantly higher in all bouts compared with phosphagen and glycolytic contributions. Low positive and negative correlations were seen between WOxi, VO2mean, sum of attacks and defense times, and the sum of time without attacks and defenses. Direct-elimination epée matches consist of high-intensity intermittent exercise, and the oxidative contribution is 80% to 90%. Improving aerobic conditioning may support high-intensity intermittent actions during entire epée matches in elite fencers.

28 Blood Lactate Response of Yearling Horses on a Progressive Workload

Abstract Blood lactate measurements following exercise provide valuable insight into the metabolic response to different workloads, but minimal research has been published involving yearling horses. Therefore, the objective of the current study was to determine blood lactate response to increasing exercise intensity in yearling horses, hypothesizing that blood lactate levels would peak immediately following exercise, and gradually decrease over a 3 h post-exercise period. To test this, 32 Quarter horses of similar background (480-520 d of age; 16 geldings and 16 fillies) were randomly assigned to one of four groups (n = 8/group) and exercised using an 8-panel free-stall walker. Exercise bouts were 30 min each, divided equally in clockwise and counterclockwise directions. Test 1 consisted of walking at 1.75m/s, and test 2 consisted of horses alternating between the walk and trot at 1.75 and 4.0m/s, respectively. Blood samples were obtained at the onset (PRE) and immediately (H0), half (H0.5), one (H1), and three (H3) h post-exercise. Mean blood lactate was determined using two portable lactate analyzers previously validated for use in horses. Data were analyzed using PROC MIXED in SAS with PRE values used as a covariate. There was a group × test × time interaction (P < 0.01), where group 3 reached peak lactate concentration at H0 during test 2 (1.37 ± 0.08 mmol/L), while all other groups increased blood lactate concentrations over time to H3 post. Mean lactate post-exercise indicates that horses were able to clear lactate without a sufficient increase in systemic distribution. Values remained below the anaerobic threshold, similar to mature horses, which suggests that sub-maximal exercise in young horses does not elicit an anaerobic response and lactate accumulation.

Novel track field test to determine Vpeak, relationship with treadmill test and 10-km running performance in trained endurance runners.

ObjectivesThe aim of this study was to determine the peak running velocity on the track field (Vpeak_TF) based on the laboratory treadmill test (Vpeak_T), and relate the Vpeak values as well as their correlation with the 10-km running performance in trained endurance runners.MethodTwenty male trained endurance runners (age: 29.5 ± 5.3 years; V̇O2max: 67.5±17.6 ml · kg-1·min-1) performed three maximum incremental tests to determine the Vpeak: one for Vpeak_T determination and two to obtain Vpeak_TF on the official track field (400 m), and a 10-km running performance. During the incremental tests, maximum heart rate (HRmax), maximal rating of perceived exertion (RPEmax), and peak lactate concentration (LApeak) were determined.ResultsThe results showed significant difference between the Vpeak_TF and Vpeak_T (18.1 ± 1.2 vs. 19.2 ± 1.5 km·h-1, respectively), as well as the total time of the tests, the distance traveled and the RPEmax determined during the tests. A high correlation was observed between the Vpeak values (r = 0.94), and between Vpeak_TF and Vpeak_T with 10-km running performance (r = -0.95 vs. r = -0.89, respectively).ConclusionsThe good agreement and association with Vpeak_T and high correlation with 10-km running performance demonstrate that the novel track field test is efficient for Vpeak_TF determination.

Physiological Responses and Bout Analysis in Elite Kickboxers During International K1 Competitions.

Background: Kickboxing is a combat sport with various forms of competition. Kickboxing according to the K1 rules is one of the most interesting and quickly developing forms of kickboxing. According to the K1 rules, it is possible to use a variety of techniques with great force. The aim of this study was to investigate the physiological responses during a real sports fight and to perform a technical and tactical analysis of the kickboxing bout according to the K1 rules.Methods: This study was conducted during two cycles of the international kickboxing league according to the K1 rules in a group of 15 elite athletes. The indicators of technical and tactical training were evaluated in real sports bout. Blood lactate (LA) levels and heart rate (HR) were measured during and after the bout.Results: The efficiency of the attack was on average 59.3 ± 2.7, its effectiveness was 50.3 ± 10.01, and its activeness was 112.3 ± 29. The peak LA concentration was 14.6 ± 1.9 mmol/L. LA concentration did not decrease to baseline after 20 min of recovery.Conclusion: A kickboxing bout was found to induce strong physiological stress for the participants. Reported HR and LA concentration show that the intensity of the fight was close to maximal, and anaerobic metabolism played an important role during a fight.

Fatigue Induced by Repeated Changes of Direction in Élite Female Football (Soccer) Players: Impact on Lower Limb Biomechanics and Implications for ACL Injury Prevention.

BackgroundThe etiology of Anterior Cruciate Ligament (ACL) injury in women football results from the interaction of several extrinsic and intrinsic risk factors. Extrinsic factors change dynamically, also due to fatigue. However, existing biomechanical findings concerning the impact of fatigue on the risk of ACL injuries remains inconsistent. We hypothesized that fatigue induced by acute workload in short and intense game periods, might in either of two ways: by pushing lower limbs mechanics toward a pattern close to injury mechanism, or alternatively by inducing opposed protective compensatory adjustments.AimIn this study, we aimed at assessing the extent to which fatigue impact on joints kinematics and kinetics while performing repeated changes of direction (CoDs) in the light of the ACL risk factors.MethodsThis was an observational, cross-sectional associative study. Twenty female players (age: 20–31 years, 1st–2nd Italian division) performed a continuous shuttle run test (5-m) involving repeated 180°-CoDs until exhaustion. During the whole test, 3D kinematics and ground reaction forces were used to compute lower limb joints angles and internal moments. Measures of exercise internal load were: peak post-exercise blood lactate concentration, heart rate (HR) and perceived exertion. Continuous linear correlations between kinematics/kinetics waveforms (during the ground contact phase of the pivoting limb) and the number of consecutive CoD were computed during the exercise using a Statistical Parametric Mapping (SPM) approach.ResultsThe test lasted 153 ± 72 s, with a rate of 14 ± 2 CoDs/min. Participants reached 95% of maximum HR and a peak lactate concentration of 11.2 ± 2.8 mmol/L. Exercise duration was inversely related to lactate concentration (r = −0.517, p < 0.01), while neither%HRmax nor [La–]b nor RPE were correlated with test duration before exhaustion (p > 0.05). Alterations in lower limb kinematics were found in 100%, and in lower limb kinetics in 85% of the players. The most common kinematic pattern was a concurrent progressive reduction in hip and knee flexion angle at initial contact (10 players); 5 of them also showed a significantly more adducted hip. Knee extension moment decreased in 8, knee valgus moment increased in 5 players. A subset of participants showed a drift of pivoting limb kinematics that matches the known ACL injury mechanism; other players displayed less definite or even opposed behaviors.DiscussionPlayers exhibited different strategies to cope with repeated CoDs, ranging from protective to potentially dangerous behaviors. While the latter was not a univocal effect, it reinforces the importance of individual biomechanical assessment when coping with fatigue.

Renin Kinetics Are Superior to Lactate Kinetics for Predicting In-Hospital Mortality in Hypotensive Critically Ill Patients.

Whole blood lactate concentration is widely used in shock states to assess perfusion. We aimed to determine if the change in plasma renin concentration over time would be superior to the change in lactate concentration for predicting in-hospital mortality in hypotensive patients on vasopressors. Prospective, observational cohort study. Tertiary academic ICU. Adult patients on vasopressors for greater than 6 hours to maintain a mean arterial pressure greater than or equal to 65 mm Hg during January 2020. Plasma renin concentrations were measured at enrollment and at 24, 48, and 72 hours. Whole blood lactate measurements were performed according to normal standard of care. Logistic regression was performed to evaluate whether the change in renin or lactate concentration could predict in-hospital mortality. Generalized estimating equations were used to analyze the association between renin and lactate concentration and in-hospital mortality. The area under the receiver operating characteristics curve was performed to measure the discriminative ability of initial and peak renin and lactate concentration to predict mortality. The association between renin and lactate concentration above the upper limit of normal at each timepoint with in-hospital mortality was also examined. The study included 197 renin and 148 lactate samples obtained from 53 patients. The slope of the natural log (ln) of renin concentration was independently associated with mortality (adjusted odds ratio, 10.35; 95% CI, 1.40-76.34; p = 0.022), but the slope of ln-lactate concentration was not (adjusted odds ratio, 4.78; 95% CI, 0.03-772.64; p = 0.55). The generalized estimating equation models found that both ln-renin (adjusted odds ratio, 1.18; 95% CI, 1.02-1.37; p = 0.025) and ln-lactate (adjusted odds ratio, 2.38; 95% CI, 1.05-5.37; p = 0.037) were associated with mortality. Area under the receiver operating characteristics curve analysis demonstrated that initial renin could predict in-hospital mortality with fair discrimination (area under the receiver operating characteristics curve, 0.682; 95% CI, 0.503-0.836; p = 0.05), but initial lactate could not (area under the receiver operating characteristics curve, 0.615; 95% CI, 0.413-0.803; p = 0.27). Peak renin (area under the receiver operating characteristics curve, 0.728; 95% CI, 0.547-0.888; p = 0.01) and peak lactate (area under the receiver operating characteristics curve, 0.746; 95% CI, 0.584-0.876; p = 0.01) demonstrated moderate discrimination. There was no significant difference in discriminative ability between initial or peak renin and lactate concentration. At each study time point, a higher proportion of renin values exceeded the threshold of normal (40 pg/mL) in nonsurvivors than in survivors, but this association was not significant for lactate. Although there was no significant difference in the performance of renin and lactate when examining the absolute values of each laboratory, a positive rate of change in renin concentration, but not lactate concentration, over 72 hours was associated with in-hospital mortality. For each one-unit increase in the slope of ln-renin, the odds of mortality increased 10-fold. Renin levels greater than 40 pg/mL, but not lactate levels greater than 2 mmol/L, were associated with in-hospital mortality. These findings suggest that plasma renin kinetics may be superior to lactate kinetics in predicting mortality of hypotensive, critically ill patients.

A Comparison of Different Prerace Warm-Up Strategies on 1-km Cycling Time-Trial Performance.

Ischemic preconditioning (IPC) and postactivation potentiation (PAP) are warm-up strategies proposed to improve high-intensity sporting performance. However, only few studies have investigated the benefits of these strategies compared with an appropriate control (CON) or an athlete-selected (SELF) warm-up protocol. Therefore, this study examined the effects of 4 different warm-up routines on 1-km time-trial (TT) performance with competitive cyclists. In a randomized crossover study, 12 well-trained cyclists (age 32 [10] y, mass 77.7 [4.6] kg, peak power output 1141 [61] W) performed 4 different warm-up strategies-(CON) 17 minutes CON only, (SELF) a self-determined warm-up, (IPC) IPC + CON, or (PAP) CON + PAP-prior to completing a maximal-effort 1-km TT. Performance time and power, quadriceps electromyograms, muscle oxygen saturation (SmO2), and blood lactate were measured to determine differences between trials. There were no significant differences (P > .05) in 1-km performance time between CON (76.9 [5.2] s), SELF (77.3 [6.0] s), IPC (77.0 [5.5] s), or PAP (77.3 [5.9] s) protocols. Furthermore, there were no significant differences in mean or peak power output between trials. Finally, electromyogram activity, SmO2, and recovery blood lactate concentration were not different between conditions. Adding IPC or PAP protocols to a short CON warm-up appears to provide no additional benefit to 1-km TT performance with well-trained cyclists and is therefore not recommended. Furthermore, additional IPC and PAP protocols had no effect on electromyograms and SmO2 values during the TT or peak lactate concentration during recovery.

Combined Analysis of Blood Ammonia and Lactate Levels as a Practical Tool to Assess the Metabolic Response to Training Sessions in Male and Female Sprinters.

Kantanista, A, Kusy, K, Pospieszna, B, Korman, P, Wieliński, D, and Zieliński, J. Combined analysis of blood ammonia and lactate levels as a practical tool to assess the metabolic response to training sessions in male and female sprinters. J Strength Cond Res 35(9): 2591-2598, 2021-Previous research has mainly focused on blood ammonia and lactate concentration changes in response to exercise in laboratory settings. The aim of this study was to present a combined analysis of blood ammonia and lactate levels obtained during various training sessions performed under real training conditions. Differences between the sexes were also analyzed. The study subjects included 9 male and 8 female sprinters competing at the international level. The two-way analyses of variance, with repeated measures (time × sex), for lactate and blood ammonia concentrations during strength, speed (only lactate), speed with baton exchange, and speed endurance training sessions were significant. Blood ammonia and lactate levels obtained during repeated sprints were higher in male than female athletes. Peak lactate concentrations obtained from different training sessions were different in the female (F(3, 18) = 49.82, p ≤ 0.001, η2 = 0.893) and male (F(3, 21) = 312.26, p ≤ 0.001, η2 = 0.978) athletes; post hoc analyses of the men and women showed differences in maximum lactate concentration between training sessions, except in the speed and strength sessions. Peak ammonia concentrations obtained in the different training sessions were also different in the female (F(3, 18) = 121.06, p ≤ 0.001, η2 = 0.953) and male (F(3, 21) = 196.04, p ≤ 0.001, η2 = 0.965) athletes; in both the men and women, significant differences in maximum blood ammonia concentrations were found between the training sessions, except for the speed and speed with baton exchange training sessions. The results of this study indicate that the combined analysis of lactate and blood ammonia concentration provides the coach with valuable additional information about the level of adenosine triphosphate breakdown, the energy system contribution involved in muscle energy coverage during very short, repeated maximal sprints, and, most importantly, allows the coach to check whether preworkout goals were actually met.

Low Frequency Electrically Induced Muscle Exercise Modulates Glucose Tolerance and Uric Acid Levels in People with SCI

Regular exercise is an important strategy to prevent the development of several chronic non‐communicable diseases (NCDs), including metabolic inflexibility and diabetes. Skeletal muscle increases glucose uptake through two distinct pathways: the insulin receptor sensitivity pathway and the exercise induced AMPK pathway. Because people with paralysis are unable to move, they never reap the benefits of muscle exercise/activity following a meal. In addition, there is a knowledge gap regarding the influence of electrically induced exercise on nitrogen metabolism.PurposeTo determine if electrically induced exercise using electrical muscle stimulation regulates the glycemic response after an oral glucose load in people with and without a SCI. We also determined if uric acid and lactate are increased in people with SCI after electrically induced exercise.Methods10 and 9 people with and without a SCI participated in this study. Participants completed 2 sessions of a 2‐hour oral glucose tolerance test at least 7 days apart. 15 minutes after ingesting a 75g glucose beverage, participants sat passively (control) or were given a dose of electrically induced muscle stimulation delivered at a 3Hz frequency for 1‐hour, then rested for the next hour. Glucose, insulin, uric lactate, and uric acid were measured from venous blood draws at baseline, 60 minutes, and 120 minutes. Capillary glucose measurements were performed at baseline, 30, 60, 90, and 120 minutes. A mixed design analysis of variance was used for all comparisons with pairwise comparisons where appropriate. All participants provided written consent approved by the University of Iowa Institutional Review Board in compliance with the Declaration of Helsinki.ResultsAt baseline, there was no significant difference in glucose (89.6±3.2 and 88.8±3.4 mg/dL, p=0.88) and lactate (1.4±0.2 and 1.4±0.2 mmol/L, p=0.96) concentrations between people with and without SCI. We found significant differences between baseline insulin (14.4±1.7 and 5.6±1.8 μUI/mL, p=0.003) and uric acid (5.9±0.6 and 3.9±0.6 mg/dL, p=0.036) concentrations between people with and without SCI. Exercise increased the peak lactate (6.0±0.3 and 1.7±0.3 mmol/L, p&lt;0.001) and uric acid (6.9±0.1 and 5.6±0.2 mg/dL, p=0.005) levels during the oral glucose tolerance test in people with SCI. However, exercise only increased peak lactate (2.0±0.06 and 1.5±0.06 mmol/L, p=0.002) concentrations during the oral glucose tolerance test for people without SCI.ConclusionsA dose of low frequency electrically induced muscle exercise attenuated the severe glycemic response in people with SCI after a meal. Additionally, electrically induced exercise increased uric acid and lactate levels suggesting a potential increase stress to the renal system. These findings offer a unique strategy for people who are paralyzed to improve their glucose tolerance after a meal. However, attention to nitrogen metabolism balance will be an important area for future research.Support or Funding Information Research Support: This study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development: R01HD084645, R01HD082109This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Serum Lactate As Reliable Biomarker of Acute Kidney Injury in Low-risk Cardiac Surgery Patients.

SummaryBackgroundCardiac surgery-associated acute kidney injury (CSA-AKI) frequently occurs in patients assessed as low-risk for developing CSA-AKI. Neutrophil Gelatinase-Associated Lipocalin (NGAL), Kidney Injury Molecule-1 (KIM-1) and lactate are promising biomarkers of CSA-AKI but have not yet been explored in low-risk patients.AimTo evaluate urinary NGAL (uNGAL), KIM-1 and lactate as biomarkers of CSA-AKI in patients with low-risk for developing CSA-AKI.MethodsThis prospective, observational study included 100 adult elective cardiac surgery patients assessed as low-risk for developing CSA-AKI. UNGAL, KIM-1 and lactate were measured preoperatively, at the end of cardiopulmonary bypass (CPB) and 3, 12, 24 and 48 h later.ResultsFifteen patients developed CSA-AKI. Patients with CSA-AKI had significantly higher lactate but similar uNGAL and KIM-1 levels compared to patients without CSA-AKI. Unlike uNGAL and KIM-1, postoperative lactate was good biomarker of CSA-AKI with the highest odds ratio (OR) 2.7 [1.4–4.9] 24 h after CPB. Peak lactate concentration ≥ 4 mmol/L carried dramatically higher risk for developing CSA-AKI (OR 6.3 [1.9–20.5]).ConclusionsUnlike uNGAL and KIM-1, postoperative lactate was significant independent predictor of CSA-AKI with the highest odds ratio 24 h after CPB.

Blood lactate concentrations following maximal incremental test in male runners with different ages

The aim of this study was to investigate the effect of age on peak blood lactate concentration following a maximal incremental treadmill test in male recreational runners. Seventy runners from four age groups, ≤25 years; 26-35 years; 36-45 years; &gt;45 years, performed an incremental treadmill test starting at 8 km·h-1, and increasing by 1 km·h-1 every three minutes until volitional exhaustion. Blood samples were collected at baseline and at the zero, third, fifth and seventh minutes after test to determine lactate concentrations. Peak lactate concentration (LApeak) was defined for each participant as the highest value among the four samples. The lactate concentrations were influenced by the participants’ age (r = -0.47), with LApeak of the younger runners (10.8 ± 2.6 mmol·L) being higher than the values for the older age categories (8.1 ± 3.1, 7.0 ± 1.1 and 6.9 ± 2.8 mmol·L for those 26-35, 36-45 and &gt;45 years, respectively). The LApeak occurred more frequently at the third and fifth minute after the initiation of the test. In conclusion, the lactate concentrations were higher in the younger group (&lt; 25) and reached peak more frequently at the third and fifth minute after the incremental test.

Physiological Correlates of Cycling Performance in Amateur Mountain Bikers

Research background and hypothesis. Aerobic fitness of high-performance mountain bikers explains about 40% of variance in performance. This suggests that other factors such as anaerobic power and capacity as well as technical abilities need to be considered in the physiological assessment (Impellizzeri et al., 2005 a). We found a lot studies investigating track and road cyclists, but there are no studies concerning the relationship between physiological tests and cycling performance in Lithuanian mountain bikers. The aim of this study was to investigate the physiological correlates of cycling performance in amateur mountain bikers. Research methods. Fifteen Lithuanian mountain bikers participated in the study. The 10-second test was performed to estimate special alactic anaerobic power output, whereas ae 30-second Wingate test was performed to estimate composite alactic anaerobic glycolytic power output. For the evaluation of the aerobic capacity, a progressive incremental laboratory cycling test to exhaustion was performed. Research results. We found a significant negative correlation between cycling performance and alactic anaerobic relative peak power output (r = –0.534, p &lt; 0.05) and lactate concentration after the progressive incremental cycling test to exhaustion (r = –0.625, p &lt; 0.05). However, we did not find a significant correlation between cycling performance and VO 2 max (r = –0.024, p &gt; 0.05) and composite alactic anaerobic glycolytic power output (r = –0.269, p &gt; 0.05). Discussion and conclusions. Our findings suggest that alactic anaerobic power output and active glycolysis play a very important role in off-road cycling performance. This is essential because of the fast starting phase of the race and steep climbs.Keywords: mountain bike, cycling, performance, power output, maximal oxygen uptake.

Stepwise Reperfusion After Zone 1 REBOA: Is Repositioning to Zone 3 a Useful Maneuver?

Background: One limitation of resuscitative endovascular balloon occlusion of the aorta (REBOA) is hemodynamic instability upon balloon deflation due to distal hyperemia and washout of ischemic metabolites. We sought to determine whether stepwise reperfusion after supraceliac (Zone 1) REBOA by transitioning to infrarenal (Zone 3) occlusion would mitigate the physiologic consequences of balloon deflation and decrease hemodynamic instability. Methods: Twelve anesthetized swine underwent controlled hemorrhage of 25% blood volume, 45 minutes of Zone 1 REBOA, then resuscitation with shed blood. Standardized critical care began with deflation of the Zone 1 balloon in all animals, and continued for six hours. Half of the animals were randomly assigned to Zone 3 REBOA for an additional 55 minutes following Zone 1 balloon deflation. Results: There were no differences in physiology at baseline, during the initial 30 minutes of hypotension, or during the 45 minutes of Zone 1 occlusion. After Zone 1 balloon deflation, there was no difference in proximal mean arterial pressure (pMAP) with or without Zone 3 occlusion or percentage of critical care time spent within the target pMAP range between 65 and 75 mm Hg. There were also no significant differences in peak lactate concentration or resuscitation requirements. Conclusions: In an animal model of hemorrhagic shock and Zone 1 REBOA, subsequent Zone 3 aortic occlusion did not add a significant ischemic burden, but it also did not provide significant hemodynamic support. The effect of this strategy on functional outcomes warrants further study. Continued investigation is necessary to determine optimal resuscitative support strategies during reperfusion following Zone 1 REBOA

Influence of Sustained Beta-Alanine Supplementation on Body Composition and Physical Performance in College-aged Males Seeking Military Commission

The present study was designed to investigate the effects of chronic ingestion of a proprietary beta-alanine supplement on body composition, indices of strength and power performance, and markers of cardiovascular endurance in physically active, college-aged males commissioning within the armed services. Subjects (n = 30) participated in four separate testing sessions, both pre and post assessment consuming either 6.0 g/day beta-alanine or Placebo supplementation for 6 weeks. Parameters evaluated included body fat percentage (BF%), fat free mass (FFM), vertical jump (VJ), 1 repetition maximum back squat (SQ) and bench press (BP), and a repetition maximum bench press (RMBP) at 75% of the attained maximum, maximal oxygen consumption (VO2peak), respiratory exchange ratio (RER), lactate threshold (LT), and peak lactate concentration. For all variables, no significant interactions existed across condition and time (p > .05). In addition, for all variables, no significant differences existed between conditions (p > .05). Beta-alanine did not show any benefit for improving body composition or physical performance parameters in this group of individuals.

Blood lactate and oxygen consumption in soccer players: comparison between different positions on the field

OBJECTIVE: We hypothesize that in players with better aerobic fitness, lactate production was not inhibited after high-intensity exercise, regardless of the footballer's position on the field. METHOD: Sixty professional male soccer players performed cardiopulmonary exercise tests on an ergometric treadmill; respiratory gas exchanges were monitored throughout and blood lactate levels at peak effort was measured, using a portable device. The heart rate response was determined by computerized EKG. Training sessions took place over an average of ten hours per week, and the players had 6.8 years of experience in competitive soccer; they were tested a third of way into the season. The positions tested were (centerback, fullback, midfielder and striker). RESULTS: The following results (mean ± std. dev.) were obtained: (1) peak oxygen consumption of 58.8 ± 4.5 ml.kg-1.min.-1; (2), blood peak lactate of 12.3 ± 1.6 mmol.L-1; (3) maximum heart rate of 193 ± 3.3 beats. min-1; (4); oxygen consumption at the second ventilatory threshold of 49.6 ± 5.0 mL. kg-1.min-1; (5); running speed at the second ventilatory threshold of 13.3 ± 0.8 km.h-1; (6) percentage of oxygen consumption in the second ventilatory threshold of 84 ± 6%. There was no correlation between maximum aerobic level vs. peak lactate concentration (r = -0,031; p = 0.812), nor between submaximal aerobic level vs. peak lactate concentration (r = -0.146; p = 0.335) in the positions tested. CONCLUSION: Better or worse aerobic profiles according to game positions in soccer players do not influence peak lactate levels following high-intensity exercise, and confirms the study hypothesis.

Continuous Monitoring of Lactate Using Intravascular Microdialysis in High-Risk Cardiac Surgery: A Prospective Observational Study.

To assess the accuracy and applicability of a novel system, not requiring calibration, for continuous lactate monitoring with intravascular microdialysis in high-risk cardiac surgery. Single-center prospective observational study. City Hospital #1 of Arkhangelsk, Russian Federation. Twenty-one adult patients undergoing elective complex repair or replacement of two or more valves or combined valve and coronary artery cardiac surgery. After induction of anesthesia, in all patients a dedicated triple-lumen catheter functioning as a regular central venous catheter with integrated microdialysis function was inserted via the right jugular vein for continuous lactate monitoring using the intravascular microdialysis system. Lactate values displayed by the microdialysis system were compared with the reference arterial blood gas (ABG) values. In total, 432 paired microdialysis-ABG lactate samples were obtained. After surgery, the concentration of lactate increased significantly, peaking at 8 hours (p<0.05). The lactate clearance within 8 hours after peak concentration was 50% (39%-63%). There was a significant correlation between Lactatecont and Lactatecont (rho = 0.92, p<0.0001). Bland-Altman analysis showed a bias (mean difference)±limits of agreement (±1.96 SD) of 0.09±1.1 mmol/L. In patients with postoperative complications, peak lactate concentration was significantly higher compared with those without complications: 6.75 (4.43-7.75) mmol/L, versus 4.20 (3.95-4.87) mmol/L (p = 0.002). Lactate concentration increased significantly after high-risk cardiac surgery. The intravascular microdialysis technique for lactate measurement provided acceptable accuracy and can be used for continuous blood lactate monitoring in cardiac surgery.