Blood Lactate Steady State Research Articles

Blood lactate steady state during interval training: new perspectives on something already known

Blood lactate steady state during interval training: new perspectives on something already known

Blood Lactate Steady State During High Intensity Interval Training Could Be Sustained Over Continuous Maximal Lactate Steady State

BACKGROUND Several researches have described Maximal Lactate Steady State (MLSS) as a highest level of Blood Lactate (BLa) that a subject is able to sustain in steady state (SS) condition, with BLa variation no more than 1 mM, during 10 to 30 minutes of continuous prolonged exercise. However, there is little evidence of SS at high intensity interval training (HIIT), with previous studies showing higher BLa levels compared with continuous MLSS tests. Our previous work suggests that moderate SS levels (4-7 mM) can be sustained during Interval Training with passive rest (PR) of 60s. PURPOSE: Unlike to the previous design, the objective of this research is to observe BLa SS (during whole workout) at HIIT, using PR of 180 s. METHODS: Ten trained swimmers (19.0 ± 3.7 y) performed HIIT (BLa ~9 mM). The series was 6x100m freestyle with 180 s PR. BLa and heart rate (HR) were measured at 10s, 50s, 110 s and 170 s at the same time during PR every 2 reps. We applied Shapiro-Wilk test to analyze for normality. We compared BLa and HR applying Friedman test (p < 0.05) in reps 2, 4, and 6. For time performance, we applied repeated measures ANOVA (p < 0.05) in all reps. Also we determine Pearson (r) or Spearman (rs) correlation coefficient between BLa and HR. RESULTS: The mean BLa max/min were 10.01 and 8.21 mM, respectively. The time performance was 63.97 ± 3.42 sec. and non-significant differences were found between all reps. Also, we found no r/rs between BLa vs. HR at same times.CONCLUSION: Despite the significant differences between BLa during 180s PR, BLa is maintained within 8 to 10 mMol/l during whole workout. BLa did not increase more than 1.05 mM between 10 to 24 minutes from rep. 4 to 6. These SS BLa levels are larger than previously published continuous MLSS. In addition, time performance was not changed during the series. Finally, we found that HR is not valid variable to control metabolic stress during HIIT.

Effect of continuous positive airway pressure on maximal exercise capacity in patients with obstructive sleep apnea: a systematic review and meta-analysis.

Exercise capacity is impaired in obstructive sleep apnea (OSA). There are conflicting reports on the effect of continuous positive airway pressure (CPAP) on maximal exercise capacity. The objective of this review was to determine if there is a change in exercise capacity and anaerobic threshold following CPAP treatment in OSA patients. We conducted a systematic review and meta-analyses to summarize the changes in peak rate of oxygen uptake (V̇O₂ peak) or maximum rate of oxygen uptake (V̇O2 max) and anaerobic threshold (AT) during cardiopulmonary exercise testing following CPAP intervention in patients with OSA. A systematic literature review was conducted to identify published literature on markers of V̇O₂ peak, V̇O₂ max, and AT pre- vs post-CPAP using a web-based literature search of PubMed/MEDLINE, Embase, CINAHL, and Cochrane review (CENTRAL) databases. Two independent reviewers screened the articles for data extraction and analysis. The total search of all the databases returned 470 relevant citations. Following application of eligibility criteria, 6 studies were included in the final meta-analysis for V̇O₂ peak, 2 studies for V̇O₂ max, and five studies for AT. The meta-analysis showed a mean net difference in V̇O₂ peak between pre- and post-CPAP of 2.69 mL·kg-1·min-1, P = .02, favoring treatment with CPAP. There was no difference in V̇O₂ max or AT with CPAP treatment (mean net difference 0.66 mL·kg-1·min-1 [P = .78] and -144.98 mL·min-1 [P = .20] respectively). There is a paucity of high-quality studies investigating the effect of CPAP on exercise capacity. Our meta-analysis shows that V̇O₂ peak increases following CPAP treatment in patients with OSA, but we did not observe any change in V̇O₂ max or AT. Our findings should be considered preliminary and we recommend further randomized controlled trials to confirm our findings and to clarify the peak and maximum rates of oxygen uptake adaptations with CPAP therapy.

Blood Lactate Steady State Is Maintained During Moderate Intensity Interval Training Depending Rest Time Duration

Blood Lactate Steady State Is Maintained During Moderate Intensity Interval Training Depending Rest Time Duration

High-Intensity Interval Training Prescription for Combat-Sport Athletes.

Combat sports are composed of high-intensity actions (eg,attacks, defensive actions, and counterattacks in both grappling and striking situations depending on the specific sport) interspersed with low-intensity actions (eg,displacement without contact, stepping) or pauses (eg,referee stoppages), characterizing an intermittent activity. Therefore, high-intensity interval training (HIIT) is at the essence of combat-sport-specific training and is used as complementary training, as well. HIIT prescription can be improved by using intensity parameters derived from combat-sport-specific tests. Specifically, the assessment of physiological indexes (intensity associated with the maximal blood lactate steady state, maximal oxygen consumption, and maximal sprint) or of time-motion variables (high-intensity actions, low-intensity actions, and effort:pause ratio) is a key element for a better HIIT prescription because these parameters provide an individualization of the training loads imposed on these athletes. To present a proposal for HIIT prescription for combat-sport athletes, exemplifying with different HIIT protocols (HIIT short intervals, HIIT long intervals, repeated-sprint training, and sprint interval training) using combat-sport-specific actions and the parameters for the individualization of these protocols. The use of combat-sport-specific tests is likely to improve HIIT prescription, allowing coaches and strength and conditioning professionals to elaborate HIIT short intervals, HIIT long intervals, repeated-sprint training, and sprint interval training protocols using combat-sport actions, providing more specificity and individualization for the training sessions.

Critical Velocity during Intermittent Running with Changes of Direction.

We tested the hypothesis that critical velocity (CV) during intermittent running with changes of direction is reliably and accurately identified from a simple shuttle field test. We also tested the hypothesis that CV during intermittent running with changes of direction running is not equivalent to continuous linear running. Young adults performed a custom shuttle test of intermittent sprint running to reveal CV. Sprints were 18.3 m per direction, with rest between sprints of 15 s for 3 min, 10 s for 2 min, and no rest for 2 min (7 min total). To test reliability, the CV shuttle test (CVST) was performed twice. To test validity, blood lactate was assessed during two separate trials inclusive of 5% above or below CVST end velocity. To explore task specificity, CV during CVST was compared to CV obtained from three linear running time trials. Total distance and CSVT end test velocity were similar between visits (864 ± 21 m and 3.23 ± 0.13 m·s vs 900 ± 30 m and 3.21 ± 0.15 m·s, respectively). At 5% above CVST end velocity, all subjects failed to complete 20 min and had unstable blood lactate values. A steady state blood lactate profile was observed during trials 5% below end velocity and all subjects completed the trial. The CV from the CVST was lower than the CV from linear running (△ -17% ± 6%), highlighting the importance of test specificity for threshold determination. The CVST provides a reliable and accurate determination of CV and can be used by coaches, athletes, and trainers to better understand the physiological impact specific to practice or competitions involving intermittent change of direction running.

Blood Lactate Steady state Level Sustained During Rest Time In Moderate Intensity Interval Training

Blood Lactate Steady state Level Sustained During Rest Time In Moderate Intensity Interval Training

Physiological responses at critical running speed during continuous and intermittent exhaustion tests

Summary Objectives The main aim of this study was to compare the time to exhaustion and physiological responses at critical speed during continuous and intermittent running in order to provide support to use critical speed during interval training sessions. Equipments and Method Nine male runners and triathletes completed an incremental treadmill test, two track performances of 800 m and 2400 m, in order to determine the critical speed, and finally two randomized tests until exhaustion, one continuous and other intermittent running (consisting of 4 min running and 1 min of passive recovery) performed at critical speed. Results The mean critical speed was 14.8 ± 2.0 km.h −1 . The continuous and intermittent times to exhaustion were 19.3 ± 6.4 min and 37.9 ± 14.6 min respectively. The blood lactate response during continuous running showed an increase in values of about 9.0 ± 0.8 mmol.l −1 at the end of the exercise. On the other hand, only one of the 9 subjects analyzed, showed an abrupt increase in blood lactate during the intermittent running. The heart rate, perceived exertion and blood lactate measured at the end of both exhaustion tests were not significantly different compared with the incremental treadmill test values. Conclusions Our findings support the use of critical speed when looking for a blood lactate steady state during endurance interval sessions using a 4:1 ratio.

Stroking Parameters during Continuous and Intermittent Exercise in Regional-Level Competitive Swimmers

This study aimed to determine whether maximal lactate steady state (MLSS) represents a boundary above which not only physiological but also technical changes occur. On different days, 13 male swimmers (23 ± 9 years) performed the following tests: 1) a 400-m all-out swim, to determine maximal aerobic speed (S-400); 2) a series of 30-min sub-maximal swims, to determine continuous MLSS (MLSSc), and; 3) a series of 12×150 s sub-maximal swims, to determine intermittent MLSS (MLSSi). Stroke rate (SR), distance per stroke cycle (DS) and stroke index (SI) were analyzed at and above (102.5%) MLSSc and MLSSi. MLSSi (1.17 ± 0.09 m.s (- 1)) was significantly higher than MLSSc (1.13 ± 0.08 m.s (- 1)) while blood lactate concentration (mmol.L (- 1)) was similar between the 2 conditions (4.3 ± 1.1 and 4.4 ± 1.5, respectively). The increase in SR and decreases in DS and SI were significant during MLSSi, 102.5% MLSSc and 102.5% MLSSi. During MLSSc, DS also decreased significantly (- 3.6%) but with no change in SR or SI. Thus, stroking technique of regional-level competitive swimmers changes over time when they swim at or above MLSS. This is the case during both continuous and intermittent swimming, despite steady state blood lactate concentrations.

Critical power in adolescents: physiological bases and assessment using all-out exercise

This study examined whether critical power (CP) in adolescents: (1) provides a landmark for maximal steady-state exercise; and (2) can be determined using 'all-out' exercise. Nine active 14-15 year olds (6 females, 3 males) performed five cycling tests: (1) a ramp test to determine VO(2peak); (2) up to four constant power output tests to determine CP; (3-4) constant power output exercise 10% above and 10% below CP; and (5) a 3 min all-out cycle test to establish the end power (EP) at 90 and 180 s of exercise. All participants completed 30 min of exercise below CP and were characterized by steady-state blood lactate and VO(2) profiles. In contrast, time to exhaustion during exercise above CP was 15.0 ± 7.0 min and characterized by an inexorable rise in blood lactate and a rise, stabilization (~91% VO(2peak)) and fall in VO(2) (~82% VO(2peak)) prior to exhaustion. Eight out of nine participants completed the 3 min test and their EPs at 90 s (148 ± 29 W) and 180 s (146 ± 30 W) were not different from CP (146 ± 27 W) (P = 0.98). The typical error of estimates for establishing CP using EP at 90 s or 180 s of the 3 min test were 25 W (19.7% CV) and 25 W (19.6% CV), respectively. CP in active adolescence provides a valid landmark for maximal steady-state exercise, although its estimation on an individual level using the 3 min all-out test may be of limited value. VO(2peak)

Lactato mínimo em protocolo de rampa e sua validade em estimar o máximo estado estável de lactato

The objectives of this study were to evaluate the validity of the lactate minimum (LM) using a ramp protocol for the determination of LM intensity (LMI), and to estimate the exercise intensity corresponding to maximal blood lactate steady state (MLSS). In addition, the possibility of determining aerobic and anaerobic fitness was investigated. Fourteen male cyclists of regional level performed one LM protocol on a cycle ergometer (Excalibur-Lode) consisting of an incremental test at an initial workload of 75 Watts, with increments of 1 Watt every 6 seconds. Hyperlactatemia was induced by a 30-second Wingate anaerobic test (WAT) (Monark-834E) at a workload corresponding to 8.57% of the volunteer's body weight. Peak power (11.5±2 Watts/ kg), mean power output (9.8±1.7 Watts/kg), fatigue index (33.7±2.3%) and lactate 7 min after WAT (10.5±2.3 mmol/L) were determined. The incremental test identified LMI (207.8±17.7 Watts) and its respective blood lactate concentration (2.9±0.7 mmol/L), heart rate (153.6±10.6 bpm), and also maximal aerobic power (305.2±31.0 Watts). MLSS intensity was identified by 2 to 4 constant exercise tests (207.8±17.7 Watts), with no difference compared to LMI and good agreement between the two parameters. The LM test using a ramp protocol seems to be a valid method for the identification of LMI and estimation of MLSS intensity in regional cyclists. In addition, both anaerobic and aerobic fitness parameters were identified during a single session.

Determination of the lactate threshold and maximal blood lactate steady state intensity in aged rats

The reliability of the lactate threshold (LT) determined in aged rats and its validity to identify an exercise intensity corresponding to the maximal blood lactate steady state (MLSS) were analyzed. Eighteen male aged Wistar rats (approximately 365 days) were submitted to two incremental swimming tests until exhaustion, consisting of an initial load corresponding to 1% of body mass (BM) and increments of 1% BM at each 3-min with blood lactate ([lac]) measurements. The LT was determined by visual inspection (LT(V)) as well by applying a polynomial function on the [lac]/workload ratio (LT(P)) by considering the vertices of the curve. For the MLSS, twelve animals were submitted, on different days, to 3-4 exercise sessions of 30-min with workload corresponding to 4, 5 or 6% BM. The MLSS was considered the highest exercise intensity at which the [lac] variation was not higher than 0.07 mM.min(-1) during the last 20-min. No differences were observed for the test-retest results (4.9 +/- 0.7 and 5.0 +/- 0.8 %BM for LTv; and 6.0 +/- 0.6 and 5.8 +/- 0.6 %BM for LTp) that did not differ from the MLSS (5.4 +/- 0.5 %BM). The LT identified for aged rats in swimming, both by visual inspection and polynomial function, was reliable and did not differ from the MLSS.

Utilização da relação potência-tempo até exaustão em testes de caminhada para avaliação da aptidão aeróbia

O objetivo do presente estudo foi avaliar a aptidão aeróbia em testes de caminhada com carga externa aplicada por meio da inclinação da esteira, a partir da relação não linear entre inclinação da esteira e tempo até a exaustão em velocidade fixa. Doze indivíduos do gênero masculino com 23,2 ± 2,7 anos de idade, 74,0 ± 7,9kg de massa corporal e 23,7 ± 2,5kg·(m²)-1 de IMC, realizaram duas etapas de testes de caminhada em esteira ergométrica com velocidade fixa de 5,5km·h-1 em todos os testes e sobrecarga de intensidade aplicada por meio de inclinação da esteira (%). A etapa 1 consistiu de três testes retangulares até a exaustão voluntária, nas intensidades de 18%, 20% e 22% de inclinação, para determinação dos parâmetros do modelo de potência crítica por dois modelos lineares e um hiperbólico. A etapa 2 consistiu na determinação da intensidade correspondente ao máximo estado estável de lactato sanguíneo (MEEL). ANOVA demonstrou que o modelo hiperbólico (15,4 ± 1,1%) resultou em estimativa significativamente menor que os outros dois modelos lineares inclinação-tempo-1 (16,0 ± 1,0%) e hiperbólico linearizado tempo-1-inclinação (15,9 ± 1,0%), porém, houve alta correlação entre os modelos. Os dois modelos lineares superestimaram a intensidade do MEEL (14,1 ± 1,4%), e o modelo hiperbólico, mesmo sem diferença estatística, apresentou fraca correlação, com baixa concordância em relação ao MEEL. Conclui-se que a relação inclinação-tempo até a exaustão, em testes de caminhada, não permitem a estimativa de intensidade de exercício suportável por longo período de tempo.

Indirect Assessment of Lactate Minimum and Maximal Blood Lactate Steady-State Intensity for Physically Active Individuals

An indirect assessment of the running velocity corresponding to lactate minimum (LMind) and its validity to estimate the maximal blood lactate steady state (MLSS) were analyzed in 22 physically active men (24.6 +/- 4.1 years, 72.6 +/- 8.0 kg, 1.75 +/- 0.1 m, 11.9 +/- 3.7% body fat). The participants were allocated into 2 different groups (G1 and G2). The running velocities (m x min) corresponding to the 1600-m time trial (1600 mV) and lactate minimum (LM) were determined for G1 (n = 12), whereas the G2 participants (n = 10) had their MLSS identified in addition to the 1600 mV and LM tests. The LM test consisted of a 150-m sprint to elevate blood lactate ([lac]) followed by 10 minutes of recovery and then 6 x 800-m at 78, 81, 84, 87, 90, and 93% of 1600 mV, with the velocity corresponding to the lowest [lac] (YSI 2700S) identified in the LM test. The relationship between 1600 mV and LM values for G1 yielded the following equation for indirect assessment of LM velocity: LMind (m x min) = (0.7507 x 1600 mV) + 21.575. The validity of the LMind was tested in the G2 participants by comparing its results with those of the MLSS. The MLSS was identified among 3-4 constant-intensity sessions by considering the highest running velocity for which a [lac] variation was not higher than 0.05 mM x min. No differences were observed for the LM (200.7 +/- 16.8 m x min), LMind (200.8 +/- 15.1 m x min), and MLSS (201.0 +/- 15.6 m x min) for G2, and there was high correlation and agreement among parameters. The LMind was considered valid for estimating LM and MLSS values if applied to physically active individuals with characteristics similar to those of the present study; thus, it is a practical and economical alternative for trainers who cannot directly determine MLSS.

Lactate minimum in a ramp protocol and its validity to estimate the maximal lactate steady state

The objectives of this study were to evaluate the validity of the lactate minimum (LM) using a ramp protocol for the determination of LM intensity (LMI), and to estimate the exercise intensity corresponding to maximal blood lactate steady state (MLSS). In addition, the possibility of determining aerobic and anaerobic fitness was investigated. Fourteen male cyclists of regional level performed one LM protocol on a cycle ergometer (Excalibur–Lode) consisting of an incremental test at an initial workload of 75 Watts, with increments of 1 Watt every 6 seconds. Hyperlactatemia was induced by a 30-second Wingate anaerobic test (WAT) (Monark–834E) at a workload corresponding to 8.57% of the volunteer’s body weight. Peak power (11.5±2 Watts/kg), mean power output (9.8±1.7 Watts/kg), fatigue index (33.7±2.3%) and lactate 7 min after WAT (10.5±2.3 mmol/L) were determined. The incremental test identified LMI (207.8±17.7 Watts) and its respective blood lactate concentration (2.9±0.7 mmol/L), heart rate (153.6±10.6 bpm), and also maximal aerobic power (305.2±31.0 Watts). MLSS intensity was identified by 2 to 4 constant exercise tests (207.8±17.7 Watts), with no difference compared to LMI and good agreement between the two parameters. The LM test using a ramp protocol seems to be a valid method for the identification of LMI and estimation of MLSS intensity in regional cyclists. In addition, both anaerobic and aerobic fitness parameters were identified during a single session.

Determination of the anaerobic threshold and maximal lactate steady state speed in equines using the lactate minimum speed protocol

Maximal blood lactate steady state concentration (MLSS) and anaerobic threshold (AT) have been shown to accurately predict long distance events performance and training loads, as well, in human athletes. Horse endurance races can take up to 160 km and, in practice, coaches use the 4 mM blood lactate concentration, a human based fixed concentration to establish AT, to predict training loads to horse athletes, what can lead to misleading training loads. The lactate minimum speed (LMS) protocol that consists in an initial elevation in blood lactate level by a high intensity bout of exercise and then establishes an individual equilibrium between lactate production and catabolism during progressive submaximal efforts, has been proposed as a nonfixed lactate concentration, to measure individual AT and at the same time predicts MLSS for human long distance runners and basketball players as well. The purpose of this study was to determine the reliability of the LMS protocol in endurance horse athletes. Five male horses that were engaged on endurance training, for at least 1 year of regular training and competition, were used in this study. Animals were submitted to a 500 m full gallop to determine each blood lactate time to peak (LP) after these determinations, animals were submitted to a progressive 1000 m exercise, starting at 15 km h(-1) to determine LMS, and after LMS determination animals were also submitted to two 10,000 m running, first at LMS and then 10% above LMS to test MLSS accuracy. Mean LP was 8.2+/-0.7 mM at approximately 5.8+/-6.09 min, mean LMS was 20.75+/-2.06 km h(-1) and mean heart rate at LMS was 124.8+/-4.7 BPM. Blood lactate remained at rest baseline levels during 10,000 m trial at LMS, but reached a six fold significantly raise during 10% above LMS trial after 4000 and 6000 m (p<0.05) and (p<0.01) after 8000 and 10,000 m. In conclusion, our adapted LMS protocol for horse athletes proposed here seems to be a reliable method to state endurance horse athletes LT and MLSS.

BLOOD LACTATE CONCENTRATIONS DURING A CONSTANT LOAD AT AN INTENSITY CORRESPONDING TO THE AEROBICANAEROBIC THRESHOLD IN YOUNG ATHLETES

It is believed that the workload corresponding to a blood lactate concentration (BLC) of 4 mmol/l, determined through aerobic-anaerobic threshold, in adults may be maintained as long as 30min at a constant workload (steady-state BLC). However, there is a lack of studies that confirm if such a phenomenon occurs in young athletes. The purposes of this study were: (i) to investigate the existence of a steady-state of BLC during 30min of constant exercise (at an intensity corresponding to 4 mmol/l) in young athletes, and (ii) to assess possible intra-individual lactate differences during the test. Thirteen young athletes (age: 16.07 ± 1.38 yrs; weight: 61.0 ± 6.69 kg; height: 171.3 ± 5.6 cm) were evaluated both during an incremental and a constant workload test. The incremental step test was used for the determination of the workload corresponding to 4mmol/l of BLC (V4). After 3 days, the subjects performed a 30min constant load test at the previously determined V4. During both tests capillary blood was taken from the ear lobe and immediately analyzed using a enzymatic blood analyzer (YSI 1500L-Sport). During the constant test blood samples were taken at 5th, 10th, 15th, 20th, 25th and 30th min. Statistical analysis included a repeated measure Anova. The mean V4 value was 3.9 ± 0.28 m/s. Two of the thirteen subjects were not able to finish the 30 min test (final BLC was 9.82 and 7.25 mmol/l, respectively). According to Heck et al. (1985) criteria the remaining subjects completed the test with a mean steady-state BLC of 4.15 ± 1.11 mmol/l. The mean BLC in the different moments (5th, 10th, 15th, 20th, 25th and 30th) of the constnat test were, respectively: 4.21, 4.50, 4.67, 4.57, 4.87 and 4.25 mmol/l. There were no significant differences in the repeated observations (F(5,6) =1.035; p =0.474), pointing out that no evidence of intraindividual BLC differences during the 30 min test exists. Therefore, it is concluded that a blood lactate steady-state may be achieved at intensities corresponding to 4mmol/l in young athletes.

The relationship of plasma catecholamine and lactate during anaerobic threshold exercise in mitochondrial myopathies.

Sympathetic system activation is considered one of the main factors influencing lactate production during exercise in normal individuals. In order to assess the role of such activation in mitochondrial myopathies, we compared blood catecholamine levels to those of lactate during an intermittent exercise performed at workloads near anaerobic lactate threshold. Following an initial increment, the patients (n = 10) exhibited a steady-state blood lactate shifted right relative to controls (n = 7), the peaks being respectively 665 +/- 29% and 322 +/- 11% of baseline. Plasma catecholamine increase in mitochondrial myopathies was 272 +/- 21% for norepinephrine and 261 +/- 18% for epinephrine, not statistically different from controls. Lactate/norepinephrine and lactate/epinephrine area ratios were significantly higher in the subjects than in controls (2.36 versus 1.48 and 2.40 versus 1.57, respectively). The study shows that the abnormal lactate production in mitochondrial myopathies is independent of the catecholaminergic response at the transition from aerobic to anaerobic exercise.

RELATION BETWEEN STEADY STATE LACTATE CONCENTRATION AND RESPIRATORY QUOTIENT DURING PROLONGED EXERCISE OF HIGH INTENSITY

1395 The purpose of the present study was to evaluate whether deviations of the respiratory quotient (RQ) measured by spirometry (RQs) exceeding 1,0 can be ascribed solely to changes in body CO2 content. 9 male middle and long distance runners (age 22.9 ± 3.9 years, LBM 61.3 ± 5.1 kg. 4 mmol-threshold 4.47 ± 0.31 m/s) underwent two exercise tests of a constant load (4.59 ± 0.19 m/s, 15 to 30 minutes duration) with and without a 3-minute preload of supramaximal intensity (5,48 ± 0.25 m/s) on a treadmill. VCO2, VO2 (by open spirometry), arterialized capillary blood lactate concentration, PaCO2 and pH were measured to correct RQs. We used the formula given by CLODE et al. 1969 and a self developed algorithm for calculating the metabolic RQ (RQm). Our findings show that under conditions of constant load near the maximal lactate steady state blood lactate concentration (SSCLa) is associated with values of RQs clearly exceeding 1,0. Even after using the correction formulas the RQm still remains elevated. Correction by the self developed algorithm (RQGM) diminishes the steady state RQ more effectively than by the formula of CLODE et al.(RQCC). TableTableOur self developed algorithm contains correction formulas for different influences, including ventilatory, acid-base-equilibrium and those dependent on further metabolic pathways. Neglecting the latter influence RQs still clearly exceeds 1,0 even during steady state conditions (no preload: 0.9843 ± 0.025, preload: 1.036 ± 0.047). It can be concluded that the deviation of the RQs during exercise of high intensity can not be assigned solely to changes of CO2 content. Further research is needed to elucidate the kind of metabolic pathways which influence the RQs to higher values.

EQUIFINALITY OF BLOOD LACTATE STEADY STATE DURING PROLONGED EXERCISE OF LOW AND HIGH INTENSITY

1557 It is known that during constant load steady state lactate concentration(CLass) can approach 2 to 10 mmol/l. The purpose of the present study was to investigate whether CLass is independent of a preload activity and preexisting blood lactate (PLaex) concentration. We investigated 11 male middle and long distance runners (age 24.3 ± 3.4 years, LBM 63.72 ± 5.4 kg, 4-mmol-threshold 4.38 ± 0.35 m/s) by two exercise tests of a constant load (20-30 minutes duration) near the aerobic threshold (3.64 ± 0.33 m/s) and near the maximal lactate steady state (4.47 ± 0.26 m/s) with and without a 3-minute preload of supramaximal intensity (5.38 ± 0.28 m/s) on a treadmill. Arterialized capillary blood lactate concentration(sample of ear lobe), VO2, VCO2 (by open spirometry), PaCO2 and pH were measured. TableTableOur results show the change of preexisting lactate concentration by accumulation or elimination to the equifinal blood lactate steady state concentration (CLass) in 15 to 25 minutes during exercise of low intensity(minimal CLass:1.08 mmol/l) and high intensity (maximal CLass:11.16 mmol/l). These data correspond to the theory of metabolic origin of anaerobic threshold by MADER et al. 1986. We suggest following conclusion: Even at higher intensity a time and preload independent CLass exists under true oxidative steady state conditions caused by a balance between gross lactate formation and lactate elimination.