Lactate Minimum Test Research Articles

Determination of speed and assessment of conditioning in horses submitted to a lactate minimum test-alternative approaches.

The maximal lactate steady state (MLSS) is a well-known gold standard method for determining the aerobic capacity of athletic horses. Owing to its high cost and complex execution, there is a search for standardized exercise tests that can predict this value in a single session. One of the methods described for this purpose is the lactate minimum test (LMT), which could be more accurate despite being adequate to predict MLSS. This study aimed to examine the impact of training on the speed corresponding to lactate minimum speed (LMS) and to apply new mathematical methods to evaluate the fitness level of horses based on the curve obtained by the LMT. Ten Arabian horses underwent a 6-week training program based on LMS calculated by second-degree polynomial regression (LMSP). In addition, the LMS was also determined by visual inspection (LMSV), bi-segmented linear regression (LMSBI) and spline regression (LMSS). From the curve obtained during the LMT, it was possible to calculate angles α, β and ω, as well as the total area under the curve (AUCTOTAL) before (AUCPRELMS) and after (AUCPOSLMS) the LMS. The methods for determining the LMS were evaluated by ANOVA, intraclass correlation coefficient (ICC) and effect size (ES) by Cohen's d test. The Pearson correlation coefficient (r) between the proposed LMS determination methods and other mathematical methods was also calculated. Despite showing a good correlation (ICC >0.7), the LMS determination methods differed from each other (p < 0.05), albeit without a significant difference resulting from conditioning. There were reductions in α:β ratio, angle α, and AUCPOSTLMS, with the latter indicating lower lactate accumulation in the incremental phase of LMT after conditioning, in addition to an improvement in the animals' aerobic capacity. Considering that the most common methods for determining the LMS are applicable yet with low sensitivity for conditioning assessment, the approaches proposed herein can aid in analyzing the aerobic capacity of horses subjected to LMT. The mathematical models presented in this paper have the potential to be applied in human lactate-guided training program trials with a comparable study basis.

Comparison of different test protocols to determine maximal lactate steady state intensity in swimming

ObjectivesThis study compared step test, lactate minimum (LM) test and reverse lactate threshold (RLT) test protocols with maximal lactate steady state (MLSS) in free-swimming. All test protocols used fixed duration increments and high work-rate resolution (≤ 0.03 m·s−1) to ensure high sensitivity. DesignValidation study. Methods23 swimmers or triathletes (12 male and 11 female) of different ages (19.0 ± 5.9 yrs) and performance levels (400 m personal best 1.38 ± 0.13 m·s−1, FINA points 490 ± 118) completed an incremental step test (+0.03 m·s−1 every 3 min) to determine speed at 4 mmol·L−1 and at modified maximal distance method, a LM test, a RLT test and two to five 30 min tests (±0.015 m·s−1) to determine MLSS. Following a 200 m all-out and a 5 min rest, LM was determined during an incremental segment (+0.03 m·s−1 every 2 min) as the nadir of the speed-lactate curve. After a priming segment with four increments (+0.06 m·s−1), RLT was determined as the lactate apex during a reverse segment (−0.03 m·s−1) every 3 min. ResultsThe mean differences (± limits of agreement) to speed at MLSS were +1.0 ± 4.1% (speed at 4 mmol·L−1), +1.5 ± 3.5% (modified maximum distance method), −0.2 ± 4.7% (LM) and 2.0 ± 3.1% (RLT). All threshold concepts showed good agreement with MLSS pace (intraclass correlation coefficient ≥ 0.886). ConclusionsTest protocols with a fixed step duration and fine increments allowed high accuracy in estimating MLSS pace. With similar criterion agreement to the LM and RLT tests, incremental step tests appear more practicable due to less prior knowledge required and derivation of individual training zones.

Test Protocol Optimization of the Heart Rate-based Lactate Minimum Test.

The determination of the maximal lactate steady state (MLSS) requires at least two constant load tests. Therefore, different testing procedures to indirectly determine MLSS based on one single test have been developed. One such method is the application of the lactate minimum tests (LMT), where workload and heart rate-based protocols exist. The latter showed significant correlations between parameters at lactate minimum (LM) and MLSS for running and cycling. However, LM clearly underestimated MLSS. Therefore, the aim of this study was to optimize the already existing test protocol in terms of an improved agreement between LM and MLSS. Fourteen healthy endurance-trained male athletes (age: 39.7±8.2 y; height: 180.9±6.2 cm; body mass: 78.6±7.1 kg) performed four different heart rate-based LMT protocols, the original and three new protocols. Additionally, they performed several constant heart rate endurance tests for assessing MLSS exercise intensity. Heart rate, blood lactate concentration, oxygen uptake and power at LM of two of our new test protocols with an increased start intensity were closer to and no longer different from MLSS data. We conclude that these two new test protocols can be used in practice to estimate heart rate-based MLSS by means of one single exercise test.

Identification of maximal lactate steady state by a short lactate minimum test in walking

The purpose of this study was to analyze the validity of a short Lactate Minimum test (LM) to assess the maximum lactate steady state (MLSS) during walking tests. Twelve healthy young participants performed LM on a treadmill at 5.5 km·h −1 , with the intensity being incremented by inclination (%). Participants first performed a walking trial at 5.5 km·h −1 with 20% or 22% inclination until voluntary exhaustion. After 7 min of recovery an incremental test was initiated by using only 3 incremental stages that were selected based on the rate of perceived exertion (RPE). The LM intensity was identified as the lowest [bLac] during the incremental test, by using a visual inspection (LM3v) and applying a polynomial function of second order (LM3p). The MLSS intensity was also measured. ANOVA showed no difference between the intensities (i.e., treadmill inclination) of MLSS (13.3 ± 2.2%), LM3 v (12.6 ± 1.6%), and LM3p (13.4 ± 1.3%). It was possible to identify the LM during walking by using 3 stages in most of the participants expressing the MLSS intensity with good agreement and correlation between them. Le but de cette étude était d’analyser la validité d’un test lactate Minimum (LM) pour évaluer l’état stable de lactate (MLSS) pendant les tests de marche. Douze jeunes participants en santé ont effectué LM sur un tapis roulant à 5,5 km0h-1, l’intensité étant augmentée par l’inclinaison (%). Les participants ont d’abord effectué un essai ambulant à 5,5 km0h-1 avec une inclinaison de 20 % ou 22 % jusqu’à l’épuisement volontaire. Après 7 min de récupération, un test incrémental a été initié en utilisant seulement 3 étapes incrémentales sélectionnées en fonction du taux d’effort perçu (RPE). L’intensité LM a été identifiée comme la plus faible [bLac] pendant le test incrémental, en utilisant une inspection visuelle (LM3v) et en appliquant une fonction polynomiale de second ordre (LM3p). L’intensité MLSS a également été mesurée. L’Anova n’a montré aucune différence entre les intensités (c’est-à-dire l’inclinaison du tapis roulant) de MLSS (13,3 ± 2,2 %), LM3 v (12,6 ± 1,6 %) et LM3p (13,4 ± 1,3 %). Il a été possible d’identifier le LM pendant la marche en utilisant 3 étapes dans la plupart des participants exprimant l’intensité MLSS avec un bon accord et une corrélation entre eux.

Load-matched acute and chronic exercise induce changes in mitochondrial biogenesis and metabolic markers

We investigated the effects of acute and chronic exercise, prescribed in different intensity zones, but with total load-matched on mitochondrial markers (cytochrome C oxidase subunit IV (COX-IV), mitochondrial transcription factor A (Tfam), and citrate synthase (CS) activity in skeletal muscles, heart, and liver), glycogen stores, aerobic capacity, and anaerobic index in swimming rats. For this, 2 experimental designs were performed (acute and chronic efforts). Load-matched exercises were prescribed below, above, and on the anaerobic threshold (AnT), determined by the lactate minimum test. In chronic programs, 2 training prescription strategies were assessed (monotonous and linear periodized model). Results show changes in glycogen stores but no modification in the COX-IV and Tfam contents after acute exercises. In the chronic protocols, COX-IV and Tfam proteins and CS adaptations were intensity- and tissue-dependent. Monotonous training promoted better adaptations than the periodized model. Training at 80% of the AnT improved both performance variables, emphasizing the anaerobic index, concomitant to CS and COX-IV improvement (soleus muscle). The aerobic capacity and CS activity (gastrocnemius) were increased after 120% AnT training. In conclusion, acute exercise protocol did not promote responses in mitochondrial target proteins. An intensity and tissue dependence were reported in the chronic protocols, highlighting training at 80 and 120% of the AnT. Novelty: Load-matched acute exercise did not enhance COX-IV and Tfam contents in skeletal muscles, heart, and liver. In chronic exercise, COX-IV, Tfam, and CS activity adaptations were intensity- and tissue-dependent. Monotonous training was more efficient than the periodized linear model in adaptations of target proteins and enzymatic activity.

Heart Rate-based Lactate Minimum Test in Running and Cycling.

The heart rate-based lactate minimum test is a highly reproducible exercise test. However, the relation between lactate minimum determined by this test and maximal lactate steady state in running and cycling is still unclear. Twelve endurance-trained men performed this test in running and cycling. Exercise intensity at maximal lactate steady state was determined by performing several constant heart rate endurance tests for both exercise modes. Heart rate, power output, lactate concentration, oxygen uptake and rating of perceived exertion at lactate minimum, maximal lactate steady state and maximal performance were analysed. All parameters were significantly higher at maximal lactate steady state compared to lactate minimum for running and cycling. Significant correlations (p<0.05) between maximal lactate steady state and lactate minimum data were found. Peak heart rate and peak oxygen uptake were significantly higher for running versus cycling. Nevertheless, the exercise mode had no influence on relative (in percentage of maximal values) heart rate at lactate minimum (p=0.099) in contrast to relative power output (p=0.002). In conclusion, all measured parameters at lactate minimum were significantly lower but highly correlated with values at maximal lactate steady state in running and cycling, which allows to roughly estimate exercise intensity at maximal lactate steady state with one single exercise test.

Effects of surgical face masks on cardiopulmonary parameters during steady state exercise

Wearing face masks reduce the maximum physical performance. Sports and occupational activities are often associated with submaximal constant intensities. This prospective crossover study examined the effects of medical face masks during constant-load exercise. Fourteen healthy men (age 25.7 ± 3.5 years; height 183.8 ± 8.4 cm; weight 83.6 ± 8.4 kg) performed a lactate minimum test and a body plethysmography with and without masks. They were randomly assigned to two constant load tests at maximal lactate steady state with and without masks. The cardiopulmonary and metabolic responses were monitored using impedance cardiography and ergo-spirometry. The airway resistance was two-fold higher with the surgical mask (SM) than without the mask (SM 0.58 ± 0.16 kPa l−1 vs. control [Co] 0.32 ± 0.08 kPa l−1; p < 0.01). The constant load tests with masks compared with those without masks resulted in a significantly different ventilation (77.1 ± 9.3 l min−1 vs. 82.4 ± 10.7 l min−1; p < 0.01), oxygen uptake (33.1 ± 5 ml min−1 kg−1 vs. 34.5 ± 6 ml min−1 kg−1; p = 0.04), and heart rate (160.1 ± 11.2 bpm vs. 154.5 ± 11.4 bpm; p < 0.01). The mean cardiac output tended to be higher with a mask (28.6 ± 3.9 l min−1 vs. 25.9 ± 4.0 l min−1; p = 0.06). Similar blood pressure (177.2 ± 17.6 mmHg vs. 172.3 ± 15.8 mmHg; p = 0.33), delta lactate (4.7 ± 1.5 mmol l−1 vs. 4.3 ± 1.5 mmol l−1; p = 0.15), and rating of perceived exertion (6.9 ± 1.1 vs. 6.6 ± 1.1; p = 0.16) were observed with and without masks. Surgical face masks increase airway resistance and heart rate during steady state exercise in healthy volunteers. The perceived exertion and endurance performance were unchanged. These results may improve the assessment of wearing face masks during work and physical training.

Differences in iron intake during pregnancy influence in trainability response of male rat offspring.

ABSTRACTObjective:To evaluate if different concentrations of iron in diets during pregnancy would interfere in the aerobic and anaerobic performance of the offspring, observed during 8-week swimming training and measured by lactate minimum test.Methods:Pregnant rats were divided into four groups with different dietary iron concentrations: standard (40mg/kg), supplementation (100mg/kg), restriction since weaning, and restriction only during pregnancy (4mg/kg). After birth, the offspring were assigned to their respective groups (Standard Offspring, Supplementation Offspring, Restriction Offspring or Restriction Offspring 2). The lactate minimum test was performed at three time points: before starting exercise training, after 4 weeks and after 8 weeks of exercise training.Results:The Restriction Offspring Group had a significant reduction in the concentration of lactate minimum and in swimming time to exhaustion, after 4 and 8 weeks of training as compared to before training. Therefore, the results showed the Restriction Offspring Group was not able to maintain regularity during training in lactate minimum tests.Conclusion:Our results suggested the Restriction Offspring Group showed a marked decrease in its performance parameters, which may have occurred due to iron restriction.

Effects of Seasonal Training Load on Performance and Illness Symptoms in Water Polo.

Brisola, GMP, Claus, GM, Dutra, YM, Malta, ES, de Poli, RAB, Esco, MR, and Zagatto, AM. Effects of seasonal training load on performance and illness symptoms in water polo. J Strength Cond Res 34(2): 406-413, 2020-The purpose of the study was to describe the training load distribution of a young female water polo team in different cycles of the season and verify its subsequent effects on specific fitness measured by the repeated sprints ability (RSA) test, aerobic endurance measured by the lactate minimum test, incidence and severity of upper respiratory tract infection (URTI) symptoms, and muscle damage markers. The training load (i.e., rating of perceived exertion × session duration) of 20 young female water polo players (mean ± SD: age = 15.65 ± 1.3 years; body mass = 60.93 ± 11.0 kg; height = 1.62 ± 0.1 m) was monitored, and the incidence and severity of URTI was assessed during part of the season. In addition, we assessed the lactate minimum speed (LMS), RSA, creatine kinase (CK), and lactate dehydrogenase (LDH) blood concentration during the season. The level of significance set was p < 0.05. The training loads were higher in the specific period (p < 0.01), whereas a high incidence of URTI was observed in the general cycle. The LMS was greater in the general cycle (p < 0.05), whereas total time and best time in the RSA test were greater in the competitive cycle (p < 0.05). The CK and LDH concentrations were significantly lower during the competitive cycle (p < 0.01). The general cycle of a female water polo team is critical regarding URTI and muscle damage, even with smaller training loads than the specific period.

Comparison of Different Blood Lactate Threshold Concepts for Constant Load Performance Prediction in Spinal Cord Injured Handcyclists.

BackgroundEndurance capacity is one of the main performance determinants in handcycling. There are two exercise test procedures primarily applied to determine endurance capacity, to verify training adaptations and predict race performance. This study aims to evaluate the agreement of these applied concepts in handcycling.MethodsIn a repeated measures cross-over design, 11 highly trained male spinal cord injured (Th12 to L1) handcyclists (age: 40 ± 9 years, height: 183 ± 8 cm, body mass: 73.2 ± 8.5 kg) performed a graded exercise test (GXT) and a lactate minimum test (LMT) to determine lactate threshold at 4 mmol L–1 (LT4 mmol L−1) and lactate minimum (LM), respectively. The agreement of both lactate thresholds concepts for constant load performance prediction (change of ≤ 1 mmol L–1 during the last 20 min) was evaluated within constant load tests (CLT; 30 min) at a power output (PO) corresponding to LT4 mmol L–1 and LM. Oxygen uptake (), respiratory exchange ratio (RER), heart rate (HR) and blood lactate (La) were measured during all tests.ResultsPower output at the corresponding thresholds (LT4 mmol L−1: 149 ± 34 W vs. LM: 137 ± 18 W) revealed no significant difference (p = 0.06). During the CLT at LT4 mmol⋅L−1 and LM, , and RPE were not significantly different. However, LA, RER, and HR were significantly higher (p ≤ 0.02) during CLT at LT4 mmol L−1. Bland–Altman plots indicate a wide range of dispersion for all parameters between both lactate threshold concepts. Evaluations of LT4 mmol L−1 and LM did not meet the criteria for constant load performance within the CLT for 33 and 17% of the athletes, respectively.DiscussionBoth exercise tests and the corresponding lactate threshold concept revealed appropriate estimates to predict a steady state performance for the majority of participants. However, as PO determination at LT4 mmol L−1 and LM exceeds the criteria for constant load performance (increase of ≥ 1 mmol L–1) for 33 and 17% respectively the current results indicate the common criteria for constant load performance (change of ± 1 mmol L–1) might not be sufficiently precise for elite athletes in handcycling. Consequently, exercise test results of elite athletes should be analyzed individually and verified by means of several CLT.

Caffeine Improves Hormonal and Lactate Homeostasis in Diabetic Rats

Introduction: Lactate Minimum Test (LMT) identifies a sustainable exercise intensity, in which an equilibrium is observed between production and clearance of blood lactate and the hormone influence during this physiological moment. Objective: The present study aimed to identify the levels of LM and hormones after caffeine consumption and exercise Stress Test (ST) in diabetic rats. Methods: This study was composed of 24 animals, of 60 days, allocated into four groups: Control, Diabetic, Caffeine, and Diabetes+Caffeine. The Diabetes model was induced by intraperitoneal administration of 120 mg/kg of alloxan. On the test day, 6 mg/kg of caffeine were administrated 30 minutes before the exercise Stress Test (ST) protocol. During the ST animals underwent a Stress Test (ST), in which they performed forced swimming (until exhaustion) tie to loads of 13% Body’s Weight (BW). The incremental phase of LM began with an initial load of 4% Body’s Weight (BW) and increased 0.5% every 5 min. Lactate concentration was measured 5, 7 and 9 min (mmol/L) after ST. The Incremental Progressive Test (IPT) involved swimming with loads of 4.0, 4.5, 5.0, 5.5, 6.0, and 7.0% of BW, for 5min with each. Blood samples were collected by a caudal puncture to subsequent lactate and hormone assay. Results: Performance time and lactate concentration of hyperlactatemia test, as well as Lactate Minimum (LM) and Lactate (LAC) concentration after the progressive test presented a significant difference when comparing the levels of the control group with caffeine and diabetic group (p&lt;0.05). Conclusion: It is suggested that caffeine improves lactate clearance and hormonal steady state condition of diabetic animals after hyperlactacidemia and physical exercise maintenance.

Reliability and Validity of Tethered Swimming Lactate Minimum Test and Their Relationship With Performance in Young Swimmers

To test the reliability and validity of tethered swimming lactate minimum test in young swimmers. Lactate minimum test was performed twice to test the reliability (experiment 1; n = 13). In addition, the validity was investigated through lactate minimum test relationships with tethered swimming lactate threshold and peak force obtained during graded exercise test (experiment 2; n = 11). Finally, the correlations with mean speeds observed during 200-m (s200m) and 30-minute continuous efforts (s30min) were also analyzed (experiment 3; n = 15). In all experiments, the lactate minimum test began with 3-minute all-out effort to induce lactatemia, followed by an exhaustive graded exercise test. The lactate minimum intensity and mean force during the entire 3-minute all-out effort (MF) showed high reliability (coefficient of variation < 8.9% and intraclass correlation coefficient > .93). The lactate minimum intensity was not different compared with lactate threshold (P = .22), presenting high correlations (r = .92) and agreement (95% limits of agreement = ±7.9N). The mean force during the entire 3-minute all-out effort was similar to peak force obtained during graded exercise test (P = .41), presenting significant correlations (r = .88) and high indices of agreement (95% limits of agreement = ±11.3N). In addition, lactate minimum test parameters correlated both with mean speeds observed during 200-m (r > .74) and 30-minute continuous efforts (r > .70). Thus, tethered swimming lactate minimum test can be used for training recommendations and to monitor aerobic adaptations in young swimmers.

Evaluation of anaerobic threshold in non-pregnant and pregnant rats.

Several studies present different methodologies and results about intensity exercise, and many of them are performed in male rats. However, the impact of different type, intensity, frequency and duration of exercise on female rats needs more investigation. From the analysis of blood lactate concentration during lactate minimum test (LacMin) in the swimming exercise, the anaerobic threshold (AT) was identified, which parameter is defined as the transition point between aerobic and anaerobic metabolism. LacMin test is considered a good indicator of aerobic conditioning and has been used in prescription of training in different exercise modalities. However, there is no evidence of LacMin test in female rats. The objective was to determine AT in non-pregnant and pregnant Wistar rats. The LacMin test was performed and AT defined for mild exercise intensity was from a load equivalent to 1% of body weight (bw), moderate exercise as carrying 4% bw and severe intensity as carrying 7% bw. In pregnant rats, the AT was reached at a lower loading from 5.0% to 5.5% bw, while in non-pregnant the load was from 5.5% to 6.0% bw. Thus, this study was effective to identify exercise intensities in pregnant and non-pregnant rats using anaerobic threshold by LacMin test.

Accuracy of a Modified Lactate Minimum Test and Reverse Lactate Threshold Test to Determine Maximal Lactate Steady State

Wahl, P, Manunzio, C, Vogt, F, Strütt, S, Volmary, P, Bloch, W, and Mester, J. Accuracy of a modified lactate minimum test and reverse lactate threshold test to determine maximal lactate steady state. J Strength Cond Res 31(12): 3489-3496, 2017-This study evaluated the accuracy of a modified lactate minimum test (mLMT), a modified reverse lactate threshold test (mRLT), compared with 2 established threshold concepts (onset of blood lactate accumulation [OBLA] and modified maximal deviation method [mDmax]) to determine power output at maximal lactate steady state (MLSS) in cycling. Nineteen subjects performed an mLMT, mRLT, graded exercise test (100 W start, +20 W every 3 minutes) and 3 or more constant-load tests of 30 minutes to determine power output at MLSS. The mLMT and mRLT both consisted of an initial lactate priming segment, followed by a short recovery phase. Afterward, the initial load of the subsequent incremental or reverse segment was calculated individually and was increased or decreased by 10 W every 90 seconds, respectively. The mean difference to MLSS was +2 ± 7 W (mLMT), +5 ± 10 W (mRLT), +9 ± 21 W (OBLA), and +6 ± 14 W (mDmax). The correlation between power output at MLSS and mLMT was highest (r = 0.99), followed by mRLT (r = 0.98), mDmax (r = 0.95), and OBLA (r = 0.90). Because of the higher accuracy of the mLMT and the mRLT to determine MLSS compared with OBLA and mDmax, we suggest both tests as valid and meaningful concepts to estimate power output at MLSS in one single test in moderately trained to well-trained athletes. Additionally, our modified tests provide anaerobic data and do not require detailed knowledge of the subjects' training status compared with previous LMT or RLT protocols.

Effect of mathematical modelling on determining lactate minimum test parameters before and after seven weeks of monitored training

Summary Objectives The aim of this study was to investigate whether lactate minimum test parameters after seven weeks of training are dependent on mathematical modelling. Equipment and methods Eight female elite basketball athletes (age 20 ± 1 years; body mass 69.2 ± 5.6 kg; height 173.8 ± 9.1 cm; fat mass 21 ± 4%) were evaluated. Athletes were subjected to the lactate minimum test before and after seven weeks of training (pre-competitive phase). The rating of perceived exertion (RPE) test was applied 30 minutes after the sessions and used to quantitate the individualized training intensities. The training volume was determined by the duration of the session. Monotony and strain were calculated by derivations of the training load. The lactate minimum test consisted of three phases: (a) hyperlactatemia induction; (b) 8-min passive recovery; and (c) incremental test (3 min stages/intensities of 8, 9, 10, 11 and 12 km h −1 ). Two non-linear (cubic spline and 2 order polynomial) and two linear (linear 1 and linear 2) mathematical functions were used to calculate the lactate minimum intensity, [Lac] at lactate minimum intensity and time at lactate minimum intensity. Statistical significance was set at P Results Only the first week presented higher load, monotony and strain values than those in the other weeks. No interaction (moment × mathematical model) was found for the lactate minimum intensity ( P = 0.685; power = 0.145), [Lac] at lactate minimum intensity ( P = 0.753; power = 0.061) and time at lactate minimum intensity ( P = 0.835). Significant relationships were not obtained for time at lactate minimum intensity before and after the training period. Similar results were obtained for the linear 1 model when compared with the other models. Conclusions The results of the present investigation demonstrate that lactate minimum test parameter determination after seven weeks of training is not dependent on the mathematical modelling method used; however, further investigations are required regarding the linear 1 model because significant relationships were not observed with the other models both before and after the training period.

Reliability and Validity of a New Specific Field Test of Aerobic Capacity with the Ball for Futsal Players.

The aim of this study was to establish the validity and reliability and verification of the reproducibility of the lactate minimum test (LM) to predict the maximal lactate steady state exercise intensity (MLSS) on a futsal-specific circuit (Futsal_circuit) which takes into consideration the technical movements performed. 16 male Brazilian futsal players (body mass: 67.7±8.3 kg; height: 1.73±0.05 m) were distributed randomly into 2 studies with 8 athletes in each (Study A - reproducibility; Study B - validity). First, aerobic capacity was determined by adapting the protocol of the LM to the futsal_circuit. In study A, the evaluation was repeated after 7 days (test e re-test) and, in study B, the MLSS on the futsal_circuit was performed. LM intensity (test=7.7±0.3 km.h-1; retest=7.7±0.4 km.h-1) showed a concordance (CV=4.13 and ET=0.32) on study A. No significant differences, high association (r=0.80; p<0.05) and concordance (lower limits: -0.58 km.h-1; Upper limits: 0.55 km.h-1) between LM and MLSS (7.5±0.5 km.h-1 LM; 7.5±0.4 km.h-1 MLSS) on study B. According to the results, we can conclude that the Futsal_circuit is reliable, reproducible and valid for assessing the functional aerobic capacity of futsal players.

Aerobic and Anaerobic Swimming Force Evaluation in One Single Test Session for Young Swimmers.

This study aims to propose and validate the tethered swimming lactate minimum test (TSLacmin) estimating aerobic and anaerobic capacity in one single test session, using force as measurement parameter. 6 male and 6 female young swimmers (age=15.7±1.1 years; height=173.3±9.5 cm; weight=66.1±9.5 kg) performed 4 sessions comprising i) an all-out 30 s test and incremental test (TSLacmin); ii) 30 min of tethered swimming at constant intensity (2 sessions); iii) free-swimming time trials used to calculate critical velocity. Tethered swimming sessions used an acquisition system enabling maximum (Fmax) and mean (Fmean) force measurement and intensity variation. The tethered all-out test lasting 30 s resulted in hyperlactatemia of 7.9±2.0 mmol·l-1. TSLacmin presented a 100% success applicability rate, which is equivalent to aerobic capacity in 75% of cases. TSLacmin intensity was 37.7±7.3 N, while maximum force in the all-out test was 105±27 N. Aerobic and anaerobic TSLacmin parameters were significantly related to free-swimming performance (r=-0.67 for 100 m and r=-0.80 for 200 m) and critical velocity (r=0.80). TSLacmin estimates aerobic capacity in most cases, and both aerobic and anaerobic force parameters are well related to critical velocity and free swimming performance.

The Lactate Minimum Test: Concept, Methodological Aspects and Insights for Future Investigations in Human and Animal Models.

In 1993, Uwe Tegtbur proposed a useful physiological protocol named the lactate minimum test (LMT). This test consists of three distinct phases. Firstly, subjects must perform high intensity efforts to induce hyperlactatemia (phase 1). Subsequently, 8 min of recovery are allowed for transposition of lactate from myocytes (for instance) to the bloodstream (phase 2). Right after the recovery, subjects are submitted to an incremental test until exhaustion (phase 3). The blood lactate concentration is expected to fall during the first stages of the incremental test and as the intensity increases in subsequent stages, to rise again forming a “U” shaped blood lactate kinetic. The minimum point of this curve, named the lactate minimum intensity (LMI), provides an estimation of the intensity that represents the balance between the appearance and clearance of arterial blood lactate, known as the maximal lactate steady state intensity (iMLSS). Furthermore, in addition to the iMLSS estimation, studies have also determined anaerobic parameters (e.g., peak, mean, and minimum force/power) during phase 1 and also the maximum oxygen consumption in phase 3; therefore, the LMT is considered a robust physiological protocol. Although, encouraging reports have been published in both human and animal models, there are still some controversies regarding three main factors: (1) the influence of methodological aspects on the LMT parameters; (2) LMT effectiveness for monitoring training effects; and (3) the LMI as a valid iMLSS estimator. Therefore, the aim of this review is to provide a balanced discussion between scientific evidence of the aforementioned issues, and insights for future investigations are suggested. In summary, further analyses is necessary to determine whether these factors are worthy, since the LMT is relevant in several contexts of health sciences.

Two water environment adaptation models enhance motor behavior and improve the success of the lactate minimum test in swimming rats

Abstract AIMS This study was designed to investigate the effects of 14 water environment adaptation days on motor behavior and physiological condition of swimming rats. METHODS Sixty male Wistar rats were divided into four groups-baseline (Bl) and control (Co) groups-which did not perform the water environment adaptation; and sub (SubAnT) and (SupraAnT) anaerobic threshold groups, which performed 14 water environment adaptation days with sub or supra anaerobic threshold progressive loads (from the tenth day), respectively. The climbing-swimming prevalence (i.e. motor behavior) was analyzed during the water environment adaptation days. Lactate minimum test (LMT) parameters and muscular/hepatic glycogen content in addition to serum creatine kinase were also measured. RESULTS Animals from SubAnT and SupraAnT groups presented a lower climbing-swimming pattern throughout the extent of the experiment (p=0.000), especially after the 5th session. These results were achieved without an improvement in the LMT results or glycogen/creatine kinase. In addition, improvements of 26.6% and 25% for the LMT success rate (i.e. LMT reliability) were obtained only for SubAnT and SupraAnT animals. CONCLUSION Overall, we demonstrated that a water environment adaptation period is necessary for lowering the climbing-swimming pattern without physiological improvement.

Continuous Aerobic Training in Individualized Intensity Avoids Spontaneous Physical Activity Decline and Improves MCT1 Expression in Oxidative Muscle of Swimming Rats.

Although aerobic training has been shown to affect the lactate transport of skeletal muscle, there is no information concerning the effect of continuous aerobic training on spontaneous physical activity (SPA). Because every movement in daily life (i.e., SPA) is generated by skeletal muscle, we think that it is possible that an improvement of SPA could affect the physiological properties of muscle with regard to lactate transport. The aim of this study was to evaluate the effect of 12 weeks of continuous aerobic training in individualized intensity on SPA of rats and their gene expressions of monocarboxylate transporters (MCT) 1 and 4 in soleus (oxidative) and white gastrocnemius (glycolytic) muscles. We also analyzed the effect of continuous aerobic training on aerobic and anaerobic parameters using the lactate minimum test (LMT). Sixty-day-old rats were randomly divided into three groups: a baseline group in which rats were evaluated prior to initiation of the study; a control group (Co) in which rats were kept without any treatment during 12 weeks; and a chronic exercise group (Tr) in which rats swam for 40 min/day, 5 days/week at 80% of anaerobic threshold during 12 weeks. After the experimental period, SPA of rats was measured using a gravimetric method. Rats had their expression of MCTs determined by RT-PCR analysis. In essence, aerobic training is effective in maintaining SPA, but did not prevent the decline of aerobic capacity and anaerobic performance, leading us to propose that the decline of SPA is not fully attributed to a deterioration of physical properties. Changes in SPA were concomitant with changes in MCT1 expression in the soleus muscle of trained rats, suggestive of an additional adaptive response toward increased lactate clearance. This result is in line with our observation showing a better equilibrium on lactate production-remotion during the continuous exercise (LMT). We propose an approach to combat the decline of SPA of rats in their home cages. This new finding is worth for scientists who work with animal models to study the protective effects of exercise.