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Descripción
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| Introduction The maximal lactate steady state (MLSS) intensity corresponds to the transition between aerobic and anaerobic metabolism (1) and it is defined as the highest intensity where blood lactate concentration ([La-]) is maintained stable (2). The factors that influence the time to exhaustion at MLSS are still unclear (3,4). Therefore, the aim of the present study was to compare the physiological responses during cycling performed at MLSS and above MLSS (>MLSS), in an attempt to elucidate which factors are responsible of fatigue at this stage. Methods Twelve male amateur cyclists participated in the study (21±2.6 years; 179.8±7.5 cm; 72.2±9 kg). Each subject performed an incremental test until exhaustion and two 30 min constant load tests to determine MLSS and >MLSS. MLSS was defined as the highest workload that could be maintained with an increase in [La-] lower than 1.0 mmol?L-1 during the final 20 min of the tests (2,3). Cardiorespiratory and blood parameters were measured throughout the tests. Two way ANOVA with repeated measures was used to determine differences between MLSS and >MLSS. The significant level was set at ?0.05. Results The power output at MLSS and >MLSS was 280±28 W (81.8±7 % VO2máx) vs. 297±29 W (87.3±7.7 % VO2máx). Due to exhaustion, only three cyclists were able to complete the 30 min at >MLSS test. There were not significant differences between MLSS and >MLSS tests in cardiorespiratory variables, except in oxygen uptake and ventilation at 30 min. The acid-base response was similar between the two intensities respect the pH values at 30 min (7.35±0.03 vs. 7.33±0.05, for MLSS and >MLSS respectively), however we found significant differences in [La-] at 30 min: 3.80±0.75 vs. 6.85±2.37 mmol?L-1, for MLSS and >MLSS respectively. Discussion Despite there were no differences in cardiorespiratory variables and pH response between the end of MLSS and >MLSS tests, fatigue occurred in 75% of the subjects. Related studies have shown that exhaustion at MLSS appears whilst homeostasis is still maintained, according to the central governor model (3). The similar response between MLSS and >MLSS does not explain the cause of the fatigue at >MLSS and therefore there is an open question concerning why most of the cyclist are not able to maintain exercise performance at >MLSS. References 1. Dekerle, J, et al. Eur J Appl Physiol (2003);89:281-8 2. Beneke, R. Eur J Appl Physiol (2003);89:95-9 3. Baron, B, et al. Br J Sports Med (2008);42:528-33 4. Fontana, P, et al. Eur J Appl Physiol (2009);107:187-92 | |
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Internacional
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Si |
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Nombre congreso
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16th Annual Congress of the European College os Sport Science |
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Tipo de participación
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960 |
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Lugar del congreso
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Liverpool |
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Revisores
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Si |
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ISBN o ISSN
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978-09568903-0-6 |
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DOI
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Fecha inicio congreso
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06/07/2011 |
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Fecha fin congreso
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09/07/2011 |
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Desde la página
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169 |
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Hasta la página
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169 |
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Título de las actas
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Book of abstracts |