Methods for estimating the maximal lactate steady state in trained cyclists

PURPOSE: Maximal lactate steady state (MLSS) is the highest exercise intensity at which blood lactate concentration (HLa) remains stable. In this study, we examined the validity of simulated 5-km and 40-km time trials (TT) as methods for estimating average speed at MLSS in cyclists. METHODS: Nine trained cyclists reported to the laboratory for five to seven exercise trials. Testing included a VO2max test, a simulated 5-km and 40-km TT, and several 30-min MLSS trials. RESULTS: Mean VO2peak was 4.42 +/- 0.13 L.min-1, whereas VO2 at MLSS (N = 8) was 3.54 +/- 0.15 L.min-1, representing 80.1 +/- 4.1% of VO2peak. HR and HLa at MLSS were 174.7 +/- 2.6 b.min-1 and 6.9 +/- 0.8 mM, respectively. MLSS speed was 36.8 +/- 1.0 km.h-1, which corresponded to 92.1 +/- 1.2% of 5 km average speed (AVS5km). Mean AVS, HLa, and HR during the 40-km TT were 36.6 +/- 0.9 km.h-1, 6.3 +/- 0.7 mM, and 174.1 +/- 2.1 b.min-1, respectively, and did not differ from those at MLSS. CONCLUSIONS: Both the (simulated) 5-km and 40-km TT can be used to estimate the MLSS in cyclists. In addition, HLa at MLSS shows a large degree of variation between riders.     

Correlations between lactate and ventilatory thresholds and the maximal lactate steady state in elite cyclists

We investigated the validity of different lactate and ventilatory threshold methods, to estimate heart rate and power output corresponding with the maximal lactate steady-state (MLSS) in elite cyclists. Elite cyclists (n = 21; 21 +/- 0.4 y; VO2peak, 5.4 +/- 0.2 l x min (-1)) performed either one (n = 10) or two (n = 11) maximal graded exercise tests, as well as two to three 30-min constant-load tests to determine MLSS, on their personal race bicycle which was mounted on an ergometer. Initial workload for the graded tests was 100 Watt and was increased by either 5 % of body mass (in Watt) with every 30 s (T30 s), or 60 % of body mass (in Watt) with every 6 min (T6min). MLSS was defined as the highest constant workload during which lactate increased no more than 1 mmol x l (-1) from min 10 to 30. In T30 s and T6 min the 4 mmol (TH-La4), the Conconi (TH-Con) and dmax (TH-Dm) lactate threshold were determined. The dmax lactate threshold was defined as the point that yields the maximal distance from the lactate curve to the line formed by the lowest and highest lactate values of the curve. In T30 s also ventilatory (TH-Ve) and Vslope (TH-Vs) thresholds were calculated. Time to exhaustion was 36 +/- 1 min for T30 s versus 39 +/- 1 min for T6 min. None of the threshold measures in T30 s, except TH-Vs (r2 = 0.77 for heart rate) correlated with either MLSS heart rate or power output. During T6 min, power output at TH-Dm was closely correlated with MLSS power (r2=0.72). Low correlations were found between MLSS heart rate and heart rate measured at TH-Dm (r2=0.46) and TH-La4 (r2=0.25), respectively, during T6 min. It is concluded that it is not possible to precisely predict heart rate or power output corresponding with MLSS in elite cyclists, from a single graded exercise test causing exhaustion within 35-40 min. The validity of MLSS predicted from an incremental test must be verified by a 30-min constant-load test.     

Validation of a single-day maximal lactate steady state assessment protocol

AIM: The classical maximal lactate steady state (MLSS) assessment protocol takes multiple days to measure thus necessitates athletes to return to a laboratory for several visits. The purpose of this study was to assess the validity and reliability of a new protocol (Palmer protocol), which proposes to measure MLSS in a single-day. METHODS: Nine endurance-trained males (age 21.1 +/- 1.6 years, VO2max of 63.2 +/- 3.2 ml x kg(-1) x min(-1)) performed the Palmer protocol and the classical MLSS assessment protocol. The classical MLSS protocol consisted of several constant-velocity runs of increasing intensity. The MLSS was defined as the highest velocity associated with an increase in blood lactate concentration ([La-]) = or < 1.0 mmol x L (-1) during the final 20 min of a 30 min run. Concurrent validity was assessed by calculating a Pearson product correlation coefficient between the running velocity at MLSS from the classical protocol and from the single-day Palmer protocol. Test-retest reliability was assessed by calculating a Pearson product correlation coefficient between the running velocities from 2 separate trials of the single-day Palmer protocol. RESULTS: The velocity at MLSS from the single-day Palmer protocol (236.4 +/- 27.8 m x min(-1)) produced a strong correlation of 0.97 (p<0.001) with the velocity at MLSS from the classical protocol (226.3 +/- 22.6 m x min(-1)). An equally strong correlation was calculated from test-retest reliability of the single-day Palmer protocol (r=0.97), (p<0.001). CONCLUSION: These results suggest that the single-day Palmer protocol is valid and reliable in the estimation of MLSS.     

Self selected speed and maximal lactate steady state speed in swimming

AIM: The purposes of this study were to ascertain whether physiological and stroking parameters remain stable during a 2-hour exercise performed at self-selected swimming speed (S4) and whether this speed corresponds to those associated with the maximal lactate steady state (SMLSS). METHODS: Ten well-trained competitive swimmers performed a maximal 400-m front crawl test, 4 30-min swimming tests in order to determine S(MLSS) and a 2-hour test swum at their preferred paces to determine self-selected swimming speed (S4), stroke rate (SR4), and stroke length (SL4) defined as the mean values observed between the 5th and the 15th min of this test. The stroking, metabolic and respiratory parameters, and ratings of perceived exertion (CR10) were reported throughout the 2-hour test. RESULTS: S4 and SMLSS were not significantly different and were highly correlated (r=0.891). S4 and SL4 decreased significantly after a steady state of 68 min and 100 min, respectively, whereas SR4 remained constant. Mean VO2, dioxide output, and heart rate values did not evolve significantly between the 10th and 120th minute of the test whereas capillary blood lactate concentration (La) decreased significantly (p<0.05). Moreover, respiratory CR10 did not evolve significantly between the 10th and the 120th minute of the test whereas general CR10 and muscular CR10 increased significantly. CONCLUSIONS: Considering the (La), SL4 and CR10 values variations, muscular parameters and a probably glycogenic depletion seem to be the main limiting factors that prevent maintaining the self selected swimming speed.     

Dependence of the maximal lactate steady state on the motor pattern of exercise

BACKGROUND: Blood lactate concentration (BLC) can be used to monitor relative exercise intensity. The highest BLC representing an equilibrium between lactate production and elimination is termed maximal lactate steady state (MLSS). MLSS is used to discriminate qualitatively between continuous exercise, which is limited by stored energy, from other types of exercise terminated because of disturbance of cellular homoeostasis. AIM: To investigate the hypothesis that MLSS intraindividually depends on the mode of exercise. METHODS: Six junior male rowers (16.5 (1.4) years, 181.7 (3.1) cm, 69.8 (3.3) kg) performed incremental and constant load tests on rowing and cycle ergometers. Measurements included BLC, sampled from the hyperaemic ear flap, heart rate, and oxygen uptake. MLSS was defined as the highest BLC that increased by no more than 1.0 mmol/l during the final 20 minutes of constant workload. RESULTS: In all subjects, MLSS was lower (p < or = 0.05) during rowing (2.7 (0.6) mmol/l) than during cycling (4.5 (1.0) mmol/l). No differences between rowing and cycling were found with respect to MLSS heart rate (169.2 (9.3) v 172.3 (6.7) beats/min), MLSS workload (178.7 (29.8) v 205.0 (20.7) W), MLSS intensity expressed as a percentage (63.3 (6.6)% v 68.6 (3.8)%) of peak workload (280.8 (15.9) v 299.2 (28.4) W) or percentage (76.4 (3.4)% v 75.1 (3.0)%) of peak oxygen uptake (60.4 (3.4) v 57.2 (8.6) ml/kg/min). CONCLUSIONS: In rowing and cycling, the MLSS but not MLSS workload and MLSS intensity intraindividually depends on the motor pattern of exercise. MLSS seems to decrease with increasing mass of the primarily engaged muscle. This indicates that task specific levels of MLSS occur at distinct levels of power output per unit of primarily engaged muscle mass.     

Stroking parameters in front crawl swimming and maximal lactate steady state speed

In order to increase or maintain speed at sub-maximal intensities, well-trained swimmers have an increase in their stroke rate, thus a decrease in their stroke. The purposes of this study were i) to ascertain whether the maximal speed from which the stroke length decreases significantly (SSLdrop) corresponds to the maximal lactate steady state swimming speed (SMLSS), and ii) to examine the effect of the exercise duration on the stroking parameters above, below, and at SMLSS. Eleven male well-trained swimmers performed an all-out 400-m front crawl test to estimate maximal aerobic speed (MAS) and four sub-maximal 30-min tests (75, 80, 85, and 90 % MAS) to determine SMLSS and SSLdrop and to analyse the evolution of the stroking parameters throughout these tests. SMLSS (88.9 +/- 3.3 % MAS) and SSLdrop (87.3 +/- 4.5 % MAS) were not significantly different from each other (p=0.41) and were highly correlated (r=0.88; p <0.001). Moreover, a slight stroke rate increase, and a stroke length decrease, were observed above S (MLSS) but were only significant for the 5 swimmers unable to maintain this speed for 30 min (p >0.05). During the 30-min tests swum below and at SMLSS, a steady state of stroking parameters was statistically reported. Thus, SMLSS seems to represent not only a physiological transition threshold between heavy and severe sub-maximal intensities but also a biomechanical boundary beyond which the stroke length becomes compromised.     

Critical swimming speed does not represent the speed at maximal lactate steady state

Critical power and critical swimming speed (CSS) are mathematically defined as intensities that could theoretically be maintained indefinitely without exhaustion. Several investigations have been conducted to attribute a physiological meaning to these variables, but results in swimming remain equivocal. Thus, the purpose of this study was to compare CSS with direct determination of the speed at maximal lactate steady state (S (MLSS)). Eight well-trained swimmers (aged 18.6 +/- 1.9 years) performed four tests to exhaustion (95, 100, 105, and 110 % of maximal aerobic speed [MAS]) in order to determine CSS from the distance-time relationship. S (MLSS) was determined from four sub-maximal 30-min constant intensity tests (ranging from 75 % to 90 % MAS). CSS (92.7 +/- 2.6 % MAS) was significantly higher than S (MLSS) (88.3 +/- 2.9 % of MAS) and the bias +/- 95 % limits of agreement for comparisons between CSS and S (MLSS) (0.07 +/- 0.13 m x s(-1)) indicated that the extent of disagreement was too great to use these two variables interchangeably. However, CSS and S (MLSS) were strongly correlated (r = 0.87; SEE = 0.033 m x s(-1); p < 0.01). Results from the present study demonstrate that in swimming, CSS does not represent the maximal speed that can be maintained without a continuous rise of blood lactate concentration and direct determination of S (MLSS) is necessary if precision is required in experimental studies.     

Determination of the exercise intensity corresponding with maximal lactate steady state in high-level basketball players

The purpose of the present study was to define the maximal lactate steady state (MLSS_meas) in high-level male basketball players and to compare it with the lactate turnpoint (LTP) and the respective point derived form a prediction method (MLSS_cal). Twelve high-level basketball players underwent one maximal and several submaximal tests on a treadmill on different days where MLSS and LTP were measured. MLSS_meas was observed at 75% of the maximal treadmill speed, at 77% of VO_2max, at 88% of HR_max and at [La^-] of 3.7 mmol.l^?1. No differences were observed between MLSS_meas and LTP in any of the measured variables. A good agreement was observed between MLSS_meas and LTP, as well as between MLSS_meas and MLSS_cal. Therefore, LTP and MLSS_cal are offered as acceptable approaches to predict MLSS, but not all the indices used to define MLSS presents high agreement between the methods used.     

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.     

Modifications of the Dmax method in comparison to the maximal lactate steady state in young male athletes

Objective: To investigate the influence of different approaches for first-rise determination on the accuracy of Dmax as an estimate of the maximal lactate steady state (MLSS).

Methods: Seventeen male cyclists and 18 male runners with different levels of endurance performance completed graded exercise tests either on a cycle ergometer or treadmill to determine Dmax, calculated by the final data point and five modifications of the first rise in blood lactate concentration. Two or more constant load tests over 30 min were performed to determine MLSS. Differences between the modifications of the first rise in blood lactate concentration as well as the corresponding Dmax variants and MLSS were tested, using one-way repeated measure ANOVA with Bonferroni post-hoc tests, and illustrated, using the Bland–Altman method. The absolute agreement was observed, using intra-class correlation coefficients, based on a single measure, absolute agreement, 2-way mixed effects model.

Results: The peak power output/running velocity of the groups averaged 275 ± 43 W and 4.3 ± 0.4 m · s^?1, respectively. The mean power output/running velocity at MLSS was 229 ± 38 W and 3.77 ± 0.38 m · s^?1. For both running and cycling the original Dmax described by Cheng et al. was significantly lower than MLSS (p < 0.01). All modifications showed good agreement with MLSS (ICC ≥0.75). According to the Bland–Altman method the mean differences of the modifications compared to MLSS in cycling ranged from ?7 (43) to 2 (41) W. In running the mean differences ranged from ?0.12 (0.34) to ?0.08 (0.35) m· s^?1.

Conclusion: We suggest using the first rise in blood lactate concentration for calculating Dmax instead of the first data point of a lactate curve as originally described. The approach of first rise determination has no substantial influence on the accuracy of Dmax compared to MLSS in cycling and running.     

An equation to predict the maximal lactate steady state from ramp-incremental exercise test data in cycling

Objectives

The maximal lactate steady state (MLSS) represents the highest exercise intensity at which an elevated blood lactate concentration ([Lac]_b) is stabilized above resting values. MLSS quantifies the boundary between the heavy-to-very-heavy intensity domains but its determination is not widely performed due to the number of trials required.

A 1-day maximal lactate steady-state assessment protocol for trained runners.

PURPOSE: Identification of the maximal lactate steady state (MLSS) involves multiple days of testing. Heart rate (HR), rating of perceived exertion (RPE), breathing frequency (bf), and race pace may be useful in estimating the MLSS, thus allowing for testing to occur in a single day. The purpose of this investigation was to design a single-session protocol for determining MLSS using HR, RPE, bf, and race pace as predictors. METHODS: Twelve endurance athletes (mean +/- SD, VO2max 64.6 +/- 7.8 mL x kg(-1) x min(-1)) performed the MLSS protocol run and two 27-min validation runs on a treadmill. Running velocity at 87% HRmax RPE of 12, bf of 32 breaths x min(-1), and race pace were used as a starting point for testing. Blood was collected every 3 min of each 9-min stage of the protocol run and analyzed for lactate (La) concentration. The velocity associated with the MLSS was determined as the average of the stage of La steady state and the stage of La accumulation. Validation runs were performed at a velocity 7.5 m x min(-1) below and 7.5 m x min(-1) above the protocol-determined MLSS. If the slower run exhibited a La steady state and the faster run an accumulation of La, then the protocol-determined MLSS value was considered valid. RESULTS: The protocol run was successful in predicting the MLSS in 9 out of 12 subjects (P < or = 0.05). CONCLUSIONS: The proposed protocol employing HR, RPE, bf, and race pace as a starting point for testing can be used to identify the MLSS in one testing session.     

Maximal constant heart rate--a heart rate based method to estimate maximal lactate steady state in running

The aim of the present study was to investigate the accuracy of the maximal constant heart rate method for predicting anaerobic threshold (AnT) in running. This method only requires a common heart rate (HR) monitor and is based on the identification of the maximal constant HR maintainable for 30 min (HRMC). HRMC, 4-mmol threshold, and maximal lactate steady state (MLSS) were determined in 31 probands. 17 probands underwent an additional MLSS retest within 2 weeks. The correlation between HR at MLSS and at MLSS retest was very close (r = 0.807; SEE = 5.25 beats x min(-1); p < 0.001). So were the correlations between HR at 4-mmol threshold and MLSS (r = 0.844; SEE = 6.43 beats x min(-1); p < 0.001) and between HRMC and HR at MLSS (r = 0.820; SEE = 6.73 beats x min(-1); p < 0.001). Mean velocities at maximum constant HR trials and MLSS (r = 0.895; SEE = 0.185 m x s(-1); p < 0.001) as well as 4-mmol threshold and MLSS (r = 0.899; SEE = 0.186 m x s(-1); p < 0.001) were highly correlated. In conclusion, data presented in this study confirm that the determination of HRMC is a manageable method giving a highly accurate estimation of both HR and velocity at MLSS in running.     

Maximal lactate steady state is altered in the heat

The aim of this study was to compare the maximal lactate steady state (MLSS) and ventilatory threshold (VT) under different environments (TEMP: 22°C; and HOT: 40°C; 50% RH). 8 male subjects (age 23.9±2.4 years, body mass 75.9±7.3?kg and VO2(max) 47.8±4.9?mL·kg(-1)·min(-1)) performed a series of tests to determine the peak workload (W(peak)), VT and MLSS on a cycle ergometer. W(peak) was higher in the TEMP as compared to the HOT condition (225±9?W vs. 195±8?W, respectively; p<0.05). The workload at MLSS was higher at 22°C (180±11?W) than 40°C (148±11?W; p<0.05), as well as VT at 22°C (156±9?W) was higher than 40°C (128±6?W). Likewise, the blood lactate concentration at MLSS was higher at 22°C (5.60±0.26?mM) than 40°C (4.22±0.48?mM; p<0.05). The mean of heart rate (HR) was not statistically different between TEMP (168±3?bpm) and HOT (173±3?bpm) at MLSS, despite being different at trials between the 25(th) and the 30(th)?min of exercise. The HR at VT was significantly higher in HOT (153±4?bpm) as compared to the TEMP (145±2?bpm). Our results suggest that environmental conditions may influence the determination of MLSS and VT. Moreover, VT was appropriate for estimation of the workload at MLSS in the HOT.     

Maximal lactate steady state does not correspond to a complete physiological steady state

The purpose of this study was to verify whether the maximal lactate steady state (MLSS) corresponds to a physiological steady state. Eight male trained subjects performed a 30-min test on a cycle ergometer at a constant power corresponding to their own MLSS which had been previously determined. No significant variation was observed between the 10th and the 30th min for arterial lactate concentration, redox state, arterial oxygen pressure, arterial oxygen saturation, bicarbonates concentration, base excess, hematocrit, hemoglobin concentration, plasma volume, oxygen uptake, carbon dioxide output, gas exchange ratio, minute ventilation, ventilatory equivalents for oxygen and carbon dioxide, and arterial systolic blood pressure values. However, arterial carbon dioxide pressure and pH values were significantly different between the 10th and the 30th min (p < 0.01). Respiratory rate values and heart rate significantly increased (p < 0.01). These results indicate that MLSS does not correspond to a complete physiological steady state.     

The concept of maximal lactate steady state: a bridge between biochemistry,physiology and sport science

The maximal lactate steady state (MLSS) is defined as the highest blood lactate concentration (MLSSc) and work load (MLSSw) that can be maintained over time without a continual blood lactate accumulation. A close relationship between endurance sport performance and MLSSw has been reported and the average velocity over a marathon is just below MLSSw. This work rate delineates the low- to high-intensity exercises at which carbohydrates contribute more than 50% of the total energy need and at which the fuel mix switches (crosses over) from predominantly fat to predominantly carbohydrate. The rate of metabolic adenosine triphosphate (ATP) turnover increases as a direct function of metabolic power output and the blood lactate at MLSS represents the highest point in the equilibrium between lactate appearance and disappearance both being equal to the lactate turnover. However, MLSSc has been reported to demonstrate a great variability between individuals (from 2-8 mmol/L) in capillary blood and not to be related to MLSSw. The fate of enhanced lactate clearance in trained individuals has been attributed primarily to oxidation in active muscle and gluconeogenesis in liver. The transport of lactate into and out of the cells is facilitated by monocarboxylate transporters (MCTs) which are transmembrane proteins and which are significantly improved by training. Endurance training increases the expression of MCT1 with intervariable effects on MCT4. The relationship between the concentration of the two MCTs and the performance parameters (i.e. the maximal distance run in 20 minutes) in elite athletes has not yet been reported. However, lactate exchange and removal indirectly estimated with velocity constants of the individual blood lactate recovery has been reported to be related to time to exhaustion at maximal oxygen uptake.     

Lack of concordance amongst measurements of individual anaerobic threshold and maximal lactate steady state on a cycle ergometer

Introduction: The calculation of exertion intensity, in which a change is produced in the metabolic processes which provide the energy to maintain physical work, has been defined as the anaerobic threshold (AT). The direct calculation of maximal lactate steady state (MLSS) would require exertion intensities over a long period of time and with sufficient rest periods which would prove significantly difficult for daily practice. Many protocols have been used for the indirect calculation of MLSS. Objectives: The aim of this study is to determine if the results of measurements with 12 different AT calculation methods and calculation software [Keul, Simon, Stegmann, Bunc, Dickhuth (TKM and WLa), D_max, Freiburg, Geiger-Hille, Log-Log, Lactate Minimum] can be used interchangeably, including the method of the fixed threshold of Mader/OBLA’s 4 mmol/l and then to compare them with the direct measurement of MLSS. Methods: There were two parts to this research. Phase 1: results from 162 exertion tests chosen at random from the 1560 tests. Phase 2: sixteen athletes (n = 16) carried out different tests on five consecutive days. Results: There was very high concordance among all the methods [intraclass correlation coefficient (ICC) > 0.90], except Log-Log in relation to the Stegamnn, D_max, Dickhuth-WLa and Geiger-Hille. The Dickhuth-TKM showed a high tendency towards concordance, with D_max (2.2 W) and Dickhuth-WLa (0.1 W). The Dickhuth-TKM method presented a high tendency to concordance with Dickhuth-WLa (0.5 W), Freiburg (7.4 W), MLSS (2.0 W), Bunc (8.9 W), D_max (0.1 W). The calculation of MLSS power showed a high tendency to concordance, with Dickhuth-TKM (2 W), D_max (2.1 W), Dickhuth-WLa (1.5 W). Conclusion: The fixed threshold of 4 mmol/l or OBLA produces slightly different and higher results than those obtained with all the methods analyzed, including MLSS, meaning an overestimation of power in the individual anaerobic threshold. The Dickhuth-TKM, D_max and Dickhuth-WLa methods defined a high concordance on a cycle ergometer. Dickhuth-TKM, D_max, Dickhuth-WLa described a high concordance with the power calculated to know the MLSS.     

Maximal lactate steady state as a training stimulus

The present study examined the use of the maximal lactate steady state (MLSS) as an exercise training stimulus in moderately trained runners. Fourteen healthy individuals (12 male, 2 female; age 25 +/- 6 years, height 1.76 +/- 0.05 m, body mass 76 +/- 8 kg mean +/- SD) took part in the study. Following determination of the lactate threshold (LT), VO2max, running velocity at MLSS (vMLSS) and a control period of 4 weeks, participants were pair matched and split into two cohorts performing either continuous (CONT: 2 sessions/week at vMLSS) or intermittent treadmill running (INT: 2 sessions/week, 3-min repetitions 0.5 km . h (-1) above and below vMLSS). vMLSS increased in CONT by 8 % from 12.3 +/- 1.5 to 13.4 +/- 1.6 km . h (-1) (p < 0.05) and in INT by 5 % from 12.2 +/- 1.9 km . h (-1) to 12.9 +/- 1.9 km . h (-1) (p < 0.05). Running speed at the LT increased by 7 % in the CONT group (p < 0.05) and by 9 % in the INT group (p < 0.05). VO2max increased by 10 % in the CONT group (p < 0.05) and by 6 % in INT (p < 0.05). Two sessions per week at vMLSS are capable of eliciting improvements in the physiological responses at LT, MLSS, and VO2max in moderately trained runners.