| Lactate Threshold Predicting Time Trial Performance: Impact of Heat and Acclimation. | |
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MedLine Citation:
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PMID: 21527667 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The relationship between exercise performance, and lactate threshold and ventilatory threshold under two distinct environmental conditions is unknown. We examined the relationships between 6 lactate threshold methods (blood and ventilation-based) and exercise performance in cyclists under hot and cool environments. Twelve cyclists performed a lactate threshold test, a VO(2max) test, and a 1hr time-trial in hot (38°C) and cool (13°C) conditions, before and after heat acclimation. Eight control subjects completed the same tests before and after 10-days of identical exercise in a cool environment. The highest correlations were observed with the blood-based lactate indices; however, even the indirect ventilation-based indices were well-correlated with mean power during the time-trial. The ventilation-based measures had a bias that averaged 15.4±3.6 watts higher than the blood-based measures (P<0.05). The bias of blood-based measures in the hot condition was increased in which the time trial was overestimated by 37.7±3.6 watts compared with only 24.1±3.2 watts in the cool condition (P<0.05). Acclimation had no effect on the bias of the blood-based indices (P=0.51), but exacerbated the overestimation by some ventilation-based indices by an additional 34.5±14.1 watts (P<0.05). Blood-based methods to determine lactate threshold show less bias and smaller variance than ventilation-based methods when predicting time trial performance under cool environments. Of the blood-based methods, the inflection point between steady state lactate and rising lactate (INFL) was the best method to predict time-trial performance. Lastly, in the hot condition ventilation-based predictions get worse after heat acclimation, while blood-based predictions remain valid in both environments after heat acclimation. |
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Authors:
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Santiago Lorenzo; Christopher Todd Minson; Tony G Babb; John R Halliwill |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-4-28 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: - Publication Date: 2011 Apr |
Date Detail:
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Created Date: 2011-4-29 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1University of Oregon. |
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