Manipulating graded exercise test variables affects the validity of the lactate threshold and [Formula: see text].

Autor: Jamnick NA; Institute for Health and Sport, College of Sport and Exercise Science, Victoria University, Melbourne, Australia., Botella J; Institute for Health and Sport, College of Sport and Exercise Science, Victoria University, Melbourne, Australia., Pyne DB; Australian Institute of Sport, Canberra, Australia.; Research Institute for Sport and Exercise (UCRISE), University of Canberra, Canberra, Australia., Bishop DJ; Institute for Health and Sport, College of Sport and Exercise Science, Victoria University, Melbourne, Australia.; School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia.
Jazyk: angličtina
Zdroj: PloS one [PLoS One] 2018 Jul 30; Vol. 13 (7), pp. e0199794. Date of Electronic Publication: 2018 Jul 30 (Print Publication: 2018).
DOI: 10.1371/journal.pone.0199794
Abstrakt: Background: To determine the validity of the lactate threshold (LT) and maximal oxygen uptake ([Formula: see text]) determined during graded exercise test (GXT) of different durations and using different LT calculations. Trained male cyclists (n = 17) completed five GXTs of varying stage length (1, 3, 4, 7 and 10 min) to establish the LT, and a series of 30-min constant power bouts to establish the maximal lactate steady state (MLSS). [Formula: see text] was assessed during each GXT and a subsequent verification exhaustive bout (VEB), and 14 different LTs were calculated from four of the GXTs (3, 4, 7 and 10 min)-yielding a total 56 LTs. Agreement was assessed between the highest [Formula: see text] measured during each GXT ([Formula: see text]) as well as between each LT and MLSS. [Formula: see text] and LT data were analysed using mean difference (MD) and intraclass correlation (ICC).
Results: The [Formula: see text] value from GXT1 was 61.0 ± 5.3 mL.kg-1.min-1 and the peak power 420 ± 55 W (mean ± SD). The power at the MLSS was 264 ± 39 W. [Formula: see text] from GXT3, 4, 7, 10 underestimated [Formula: see text] by ~1-5 mL.kg-1.min-1. Many of the traditional LT methods were not valid and a newly developed Modified Dmax method derived from GXT4 provided the most valid estimate of the MLSS (MD = 1.1 W; ICC = 0.96).
Conclusion: The data highlight how GXT protocol design and data analysis influence the determination of both [Formula: see text] and LT. It is also apparent that [Formula: see text] and LT cannot be determined in a single GXT, even with the inclusion of a VEB.
Competing Interests: The authors have declared that no competing interests exist.
Databáze: MEDLINE
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