title: Reliability of time-to-exhaustion and selected psycho-physiological variables during constant-load cycling at the maximal lactate steady-state.
abstract: 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.
authors.affiliation: a Institute of Sports and Preventive Medicine, Saarland University, Campus, Bldg. B8 2, D-66123 Saarbrücken, Germany.|b Department of Sport, Exercise and Health, University of Basel, Birsstr. 320B, CH-4052 Basel, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Faude
authors.affiliation: a Institute of Sports and Preventive Medicine, Saarland University, Campus, Bldg. B8 2, D-66123 Saarbrücken, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Hecksteden
authors.affiliation: a Institute of Sports and Preventive Medicine, Saarland University, Campus, Bldg. B8 2, D-66123 Saarbrücken, Germany.|b Department of Sport, Exercise and Health, University of Basel, Birsstr. 320B, CH-4052 Basel, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hammes
authors.affiliation: a Institute of Sports and Preventive Medicine, Saarland University, Campus, Bldg. B8 2, D-66123 Saarbrücken, Germany.
authors.forename: Franck
authors.initials: F
authors.lastname: Schumacher
authors.affiliation: a Institute of Sports and Preventive Medicine, Saarland University, Campus, Bldg. B8 2, D-66123 Saarbrücken, Germany.|c Sports Medicine Research Laboratory, Luxembourg Institute of Health, 76, rue d'Eich, L-146 Luxembourg.
authors.forename: Eric
authors.initials: E
authors.lastname: Besenius
authors.affiliation: d Integrative and Experimental Training Science, Institute of Sport Science, University of Würzburg, Judenbühlweg 11, D-97082 Würzburg, Germany.
authors.forename: Billy
authors.initials: B
authors.lastname: Sperlich
authors.affiliation: a Institute of Sports and Preventive Medicine, Saarland University, Campus, Bldg. B8 2, D-66123 Saarbrücken, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Meyer
mesh_terms: D000328:Adult; D056352:Athletes; D001642:Bicycling; D001831:Body Temperature; D015444:Exercise; D005080:Exercise Test; D017079:Exercise Tolerance; D005221:Fatigue / Q000097:blood / Q000209:etiology*; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance; D005082:Physical Exertion; D011597:Psychomotor Performance; D015203:Reproducibility of Results; D056152:Respiratory Rate; D013997:Time Factors; D055815:Young Adult
chemical_list: D019344:Lactic Acid
keywords: endurance training; open-end exercise; physiological assessment of performance; reproducibility; variability