Reproducibility Of Performance Time And Physiological Responses During Constant-load Cycling At The Maximal Lactate Steady-state

Objectives: To examine the effect of exercise at and slightly above the maximal lactate steady state (MLSS) on self-efficacy, affect and effort, and their associations with exercise tolerance.Design: Counterbalanced, repeated measures designMethod: Participants performed two 30‐minute constant‐load cycling exercise at a power output equal to that at MLSS and 10 W above MLSS, immediately followed by a time‐to‐exhaustion test at 80% of their peak power output. Self-efficacy, affect and effort were measured before and after 30 minutes of cycling at and above MLSS.Results: Negative affect and effort higher, and self-efficacy and time to exhaustion were reduced, following cycling at MLSS + 10 W compared to cycling at the MLSS. Following exercise at the MLSS self-efficacy, affect and effort were all associated with subsequent time-to exhaustion. However, following exercise at MLSS + 10 W, only affect was associated with time-to exhaustion. Conclusions: Self efficacy, affect and effort are profoundly affected by physiological state, highlighting the influence of somatic states on perceptions and emotions during exercise. The affective response to exercise appears to be associated with exercise tolerance, indicating that the emotional, as well as physiological, responses should be considered when prescribing exercise training.

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Ventilatory and Physiological Responses in Swimmers Below and Above Their Maximal Lactate Steady State

The Journal of Strength and Conditioning Research ◽

10.1519/jsc.0000000000000504 ◽

2015 ◽

Vol 29 (10) ◽

pp. 2836-2843 ◽

Cited By ~ 4

Author(s):

Mario C. Espada ◽

Joana F. Reis ◽

Tiago F. Almeida ◽

Paula M. Bruno ◽

Veronica E. Vleck ◽

...

Keyword(s):

Steady State ◽

Physiological Responses ◽

Maximal Lactate Steady State

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Reliability of time-to-exhaustion and selected psycho-physiological variables during constant-load cycling at the maximal lactate steady-state

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2016-0375 ◽

2017 ◽

Vol 42 (2) ◽

pp. 142-147 ◽

Cited By ~ 16

Author(s):

Oliver Faude ◽

Anne Hecksteden ◽

Daniel Hammes ◽

Franck Schumacher ◽

Eric Besenius ◽

...

Keyword(s):

Steady State ◽

Oxygen Uptake ◽

Blood Lactate ◽

Maximal Oxygen Uptake ◽

Perceived Exertion ◽

Constant Load ◽

Time To Exhaustion ◽

Maximal Lactate Steady State ◽

Physiological Variables ◽

Load Tests

The maximal lactate steady-state (MLSS) is frequently assessed for prescribing endurance exercise intensity. Knowledge of the intra-individual variability of the MLSS is important for practical application. To date, little is known about the reliability of time-to-exhaustion and physiological responses to exercise at MLSS. Twenty-one healthy men (age, 25.2 (SD 3.3) years; height, 1.83 (0.06) m; body mass, 78.9 (8.9) kg; maximal oxygen uptake, 57.1 (10.7) mL·min−1·kg−1) performed 1 incremental exercise test, and 2 constant-load tests to determine MLSS intensity. Subsequently, 2 open-end constant-load tests (MLSS 1 and 2) at MLSS intensity (3.0 (0.7) W·kg−1, 76% (10%) maximal oxygen uptake) were carried out. During the tests, blood lactate concentrations, heart rate, ratings of perceived exertion (RPE), variables of gas exchange, and core body temperature were determined. Time-to-exhaustion was 50.8 (14.0) and 48.2 (16.7) min in MLSS 1 and 2 (mean change: −2.6 (95% confidence interval: −7.8, 2.6)), respectively. The coefficient of variation (CV) was high for time-to-exhaustion (24.6%) and for mean (4.8 (1.2) mmol·L−1) and end (5.4 (1.7) mmol·L−1) blood lactate concentrations (15.7% and 19.3%). The CV of mean exercise values for all other parameters ranged from 1.4% (core temperature) to 8.3% (ventilation). At termination, the CVs ranged from 0.8% (RPE) to 11.8% (breathing frequency). The low reliability of time-to-exhaustion and blood lactate concentration at MLSS indicates that the precise individual intensity prescription may be challenging. Moreover, the obtained data may serve as reference to allow for the separation of intervention effects from random variation in our sample.

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

Journal Of Science & Cycling ◽

10.28985/180630.jsc.03 ◽

2018 ◽

Vol 7 (1) ◽

pp. 9-16

Author(s):

Jose Ramon Lillo-Bevia ◽

Ricardo Moran-Navarro ◽

Alejandro Martinez-Cava ◽

Victor Cerezuela ◽

Jesus G. Pallares

Keyword(s):

Steady State ◽

Data Analysis ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Constant Load ◽

Load Test ◽

Validity And Reliability ◽

Maximal Lactate Steady State ◽

Exercise Tests ◽

Assessment Protocol

The main aim of this study is to assess the validity of a new cycling protocol to estimate the Maximal Lactate Steady-State workload (MLSS) through a one-day incremental protocol (1day_MLSS). Eleven well-trained male cyclists performed 3 to 4 trials of 30-min constant load test (48-72h in between) to determine their respective MLSS workload. Then, on separate days, each cyclist carried out two identical graded exercise tests, comprised of four 10-minute long stages, with the initial load at 63% of their respective maximal aerobic power, 0.2 W·Kg-1 increments, and blood lactate concentration (BLC) determinations each 5 min. The results of the 1day_MLSS tests were analysed through three different constructs: i) BLC difference between 5th and 10th min of each stage (DIF_5to10), ii) BLC difference between the 10th min of two consecutive stages (DIF_10to10), and iii) difference in the mean BLC between the 5th and 10th min of two consecutive stages (DIF_mean). For all constructs, the physiological steady state was determined as the highest workload that could be maintained with a BLC rise lower than 1mmol·L-1. No significant differences were detected between the MLSS workload (247 ± 22W) and any of the 1day_MLSS data analysis (250 ± 24W, 245 ± 23W and 243 ± 21W, respectively; p>0.05). When compared to the MLSS workload, strong ICCs and low bias values were found for these three constructs, especially for the DIF_10to10 workload (r=0.960; Bias=2.2 W). High within-subject reliability data were found for the DIF10_10 construct (ICC=0.846; CV=0.4%; Bias=2.2 ± 6.4W). The 1day_MLSS test and DIF_10to10 data analysis is a valid assessment to predict the MLSS workload in cycling, that considerably reduces the dedicated time, effort and human resources that requires the original test. The validity and reliability values reported in this project are higher than those achieved by other previous MLSS estimation tests.

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Physiological Responses of Continuous and Intermittent Swimming at Critical Speed and Maximum Lactate Steady State in Children and Adolescent Swimmers

Sports ◽

10.3390/sports7010025 ◽

2019 ◽

Vol 7 (1) ◽

pp. 25 ◽

Cited By ~ 1

Author(s):

Ioannis Nikitakis ◽

Giorgos Paradisis ◽

Gregory Bogdanis ◽

Argyris Toubekis

Keyword(s):

Heart Rate ◽

Steady State ◽

Critical Speed ◽

Physiological Responses ◽

Lactate Concentration ◽

Blood Lactate Concentration ◽

Metabolic Responses ◽

Maximal Lactate Steady State ◽

Children And Adolescent ◽

Maximum Lactate

Background: The purpose of this study was to compare physiological responses during continuous and intermittent swimming at intensity corresponding to critical speed (CS: slope of the distance vs. time relationship using 200 and 400-m tests) with maximal lactate steady state (MLSS) in children and adolescents. Methods: CS and the speed corresponding to MLSS (sMLSS) were calculated in ten male children (11.5 ± 0.4 years) and ten adolescents (15.8 ± 0.7 years). Blood lactate concentration (BL), oxygen uptake ( V · O2), and heart rate (HR) at sMLSS were compared to intermittent (10 × 200-m) and continuous swimming corresponding to CS. Results: CS was similar to sMLSS in children (1.092 ± 0.071 vs. 1.083 ± 0.065 m·s−1; p = 0.12) and adolescents (1.315 ± 0.068 vs. 1.297 ± 0.056 m·s−1; p = 0.12). However, not all swimmers were able to complete 30 min at CS and BL was higher at the end of continuous swimming at CS compared to sMLSS (children: CS: 4.0 ± 1.8, sMLSS: 3.4 ± 1.5; adolescents: CS: 4.5 ± 2.3, sMLSS: 3.1 ± 0.8 mmol·L−1; p < 0.05). V · O2 and HR in continuous swimming at CS were not different compared to sMLSS (p > 0.05). BL, V · O2 and HR in 10 × 200-m were similar to sMLSS and no different between groups. Conclusion: Intermittent swimming at CS presents physiological responses similar to sMLSS. Metabolic responses of continuous swimming at CS may not correspond to MLSS in some children and adolescent swimmers.

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Maximal Lactate Steady State Versus the 20-Minute Functional Threshold Power Test in Well-Trained Individuals: “Watts” the Big Deal?

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2019-0214 ◽

2020 ◽

Vol 15 (4) ◽

pp. 541-547 ◽

Cited By ~ 1

Author(s):

Erin Calaine Inglis ◽

Danilo Iannetta ◽

Louis Passfield ◽

Juan M. Murias

Keyword(s):

Steady State ◽

Field Test ◽

Power Output ◽

Constant Load ◽

Test Series ◽

Threshold Power ◽

Maximal Lactate Steady State ◽

Large Variability ◽

Power Test ◽

Induced Changes

Purpose: To (1) compare the power output (PO) for both the 20-minute functional threshold power (FTP20) field test and the calculated 95% (FTP95%) with PO at maximal lactate steady state (MLSS) and (2) evaluate the sensitivity of FTP95% and MLSS to training-induced changes. Methods: Eighteen participants (12 males: 37 [6] y and 6 females: 28 [6] y) performed a ramp-incremental cycling test to exhaustion, 2 to 3 constant-load MLSS trials, and an FTP20 test. A total of 10 participants returned to repeat the test series after 7 months of training. Results: The PO at FTP20 and FTP95% was greater than that at MLSS (P = .00), with the PO at MLSS representing 88.5% (4.8%) and 93.1% (5.1%) of FTP and FTP95%, respectively. MLSS was greater at POST compared with PRE training (12 [8] W) (P = .002). No increase was observed in mean PO at FTP20 and FTP95% (P = .75). Conclusions: The results indicate that the PO at FTP95% is different to MLSS, and that changes in the PO at MLSS after training were not reflected by FTP95%. Even when using an adjusted percentage (ie, 88% rather than 95% of FTP20), the large variability in the data is such that it would not be advisable to use this as a representation of MLSS.

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Study on Basic Coal Consumption Characteristics in Dynamic Process of 660MW Ultra-Supercritical Coal-Fired Unit

ASME 2020 Power Conference ◽

10.1115/power2020-16227 ◽

2020 ◽

Author(s):

Junjie Yin ◽

Ming Liu ◽

Junjie Yan ◽

Yongliang Zhao

Keyword(s):

Steady State ◽

Consumption Rate ◽

Constant Load ◽

Calculation Model ◽

Dynamic Processes ◽

Design Calculation ◽

Coal Consumption ◽

Steady State Condition ◽

Load Cycling ◽

Consumption Rates

Abstract With the spreading of intermittent renewable power, coal-fired power units should cycle frequently to balance the load between power supply side and demand side. Coal consumption of coal-fired units operating in dynamic processes is influenced by many factors, including thermal system, control system, heat storage variation, etc. Therefore, it is very difficult to evaluate the energy efficiency of coal-fired units operating in dynamic processes. It is important to ascertain the basic coal consumption rate in dynamic processes, which is the basis to evaluate the operation performance of coal-fired units. In this study, an off-design calculation model of 660MW ultra-supercritical coal-fired unit is developed and validated with design parameters. The developed model can be used to predict the coal consumption rates under steady-state off-design conditions. The basic coal consumption means the coal consumption of coal-fired units with operating parameters the same as target values. To calculate the basic coal consumption rate, a load cycling process is differentiated into lots of short time periods and every period is regarded as a steady-state condition with constant load, therefore the coal consumption rates in every period are equal to that of the corresponding steady-state condition. The calculation formula of basic coal consumption rates in is derived for load cycling processes. On the basis of the off-design calculation model and assumption of idealized condition, average coal consumption rates during different processes with constant load cycling rates can be calculated and analyzed. Results show that if the initial and final loads are both settled, the basic coal consumption rate remains unchanged and is independent of load cycling rate. If the load cycling amplitude remains unchanged, the basic coal consumption rate increases as the initial load decrease. The study aims to provide benchmark values for the energy consumption analysis in actual dynamic processes, and further study on coal consumption characteristics in dynamic processes will be developed based on it.

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Is the Functional Threshold Power Interchangeable With the Maximal Lactate Steady State in Trained Cyclists?

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2018-0572 ◽

2019 ◽

Vol 14 (8) ◽

pp. 1029-1035 ◽

Cited By ~ 4

Author(s):

Fernando Klitzke Borszcz ◽

Artur Ferreira Tramontin ◽

Vitor Pereira Costa

Keyword(s):

Steady State ◽

Average Power ◽

Time Trial ◽

Constant Load ◽

Threshold Power ◽

Trained Group ◽

Maximal Lactate Steady State ◽

Pearson Coefficient ◽

Large Correlation ◽

Load Tests

Purpose: Functional threshold power (FTP), determined as 95% of the average power during a 20-min time trial, is suggested as a practical test for the determination of the maximal lactate steady state (MLSS) in cycling. Therefore, the objective of the present study was to determine the validity of FTP in predicting MLSS. Methods: A total of 15 cyclists, 7 classified as trained and 8 as well trained (mean [SD] maximal oxygen uptake 62.3 [6.4] mL·kg−1·min−1, maximal aerobic power 329 [30] W), performed an incremental test to exhaustion, an FTP test, and several constant-load tests to determine the MLSS. The bias ± 95% limits of agreement (LoA), typical error of the estimate (TEE), and Pearson coefficient of correlation (r) were calculated to assess validity. Results: For the power-output measures, FTP presented a bias ± 95% LoA of 1.4% ± 9.2%, a moderate TEE (4.7%), and nearly perfect correlation (r = .91) with MLSS in all cyclists together. When divided by training level, the bias ± 95% LoA and TEE were higher in the trained group (1.4% ± 11.8% and 6.4%, respectively) than in the well-trained group (1.3% ± 7.4% and 3.0%, respectively). For the heart-rate measurement, FTP presented a bias ± 95% LoA of −1.4% ± 8.2%, TEE of 4.0%, and very large correlation (r = .80) with MLSS. Conclusion: Therefore, trained and well-trained cyclists can use FTP as a noninvasive and practical alternative to estimate MLSS.

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Determination of the Maximal Lactate Steady State by HRV in Overweight and Obese Subjects

Sports Medicine International Open ◽

10.1055/a-0883-5473 ◽

2019 ◽

Vol 03 (02) ◽

pp. E58-E64

Author(s):

Tobias Schmidt ◽

Sarah Wulff ◽

Klaus-Michael Braumann ◽

Ruediger Reer

Keyword(s):

Steady State ◽

Constant Load ◽

Bicycle Ergometer ◽

Incremental Exercise ◽

Maximal Lactate Steady State ◽

Poincaré Plot ◽

Incremental Exercise Test ◽

Load Tests ◽

Obese Subjects

AbstractThe study assessed if the maximal lactate steady state (MLSS) may be determined by HRV in overweight and obese individuals. Fourteen obese (OB) and 14 overweight (OW) participants performed an incremental exercise test and several constant-load tests on a bicycle ergometer to determine the MLSS. HRV was analysed by using time domain and non-linear parameters of the Poincaré plot. Various HRV thresholds (HRVt) were detected and compared with the MLSS. Overall, Bland-Altman plots demonstrated moderate to strong agreements between the power at the MLSS and the power at HRVt, with all HRVt overestimating the MLSS (range: − 14.6 to−19.8 W). All HRVt were detected at higher intensities (69.2–78.8%Pmax) compared to the MLSS (62.6–66.8%Pmax). The primarily vagally modulated parameter HRVtSD1 revealed higher correlations (r=0.66–0.76) and lower differences (16.8–19.9%) compared to the parameter HRVtSD2 (r=0.56–r=0.66; 22.4–22.9%). The data suggest a delayed vagal withdrawal during incremental exercise in obese and overweight individuals. For this population, the use of HRV to determine the MLSS seems questionable.

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Ramp vs. step tests: valid alternatives to determine the maximal lactate steady-state intensity?

European Journal of Applied Physiology ◽

10.1007/s00421-021-04620-9 ◽

2021 ◽

Author(s):

Kevin Caen ◽

Silvia Pogliaghi ◽

Maarten Lievens ◽

Kobe Vermeire ◽

Jan G. Bourgois ◽

...

Keyword(s):

Steady State ◽

Maximal Lactate Steady State

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