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Elevated baseline VO2 per se does not slow O2 uptake kinetics during work-to-work exercise transitions.
MedLine Citation:
PMID:  20724564     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
We investigated whether the characteristic slowing of pulmonary oxygen uptake (VO2) kinetics during "work-to-work" exercise is attributable to elevations in baseline metabolic rate (VO2) as opposed to the elevated baseline work rate, per se. We hypothesized that a step transition to a higher work rate from "unloaded" cycling, but with elevations in VO2 [and heart rate (HR)] reflective of a work-to-work transition, would result in a lengthened phase II time constant (τ(p)). Seven male subjects (mean ± SD age 27 ± 10 yr) completed 1) transitions to a high-intensity work rate from a moderate-intensity work rate (M→H) and 2) two consecutive bouts of high-intensity exercise (U→H and E→H, respectively) initiated from unloaded cycling, with the time separating the exercise bouts chosen such that the baseline VO2 for the second transition was similar to the baseline VO2 for the M→H transition. The τ(p) for M→H (48 ± 16 s) was significantly greater (P < 0.05) than the τ(p) for U→H (28 ± 8 s) and E→H (27 ± 6 s), which did not differ significantly. These findings suggest that the altered VO2 dynamics that are observed during work-to-work exercise are not related to the elevated baseline VO2 (or HR) per se; rather, these effects appear to be linked to the elevated baseline work rate, which would be expected to dictate the subsequent muscle fiber recruitment profile.
Authors:
Fred J DiMenna; Stephen J Bailey; Anni Vanhatalo; Weerapong Chidnok; Andrew M Jones
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Publication Detail:
Type:  Journal Article     Date:  2010-08-19
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  109     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-10-13     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1148-54     Citation Subset:  IM    
Affiliation:
School of Sport and Health Sciences, St. Luke's Campus, Univ. of Exeter, Heavitree Rd., Exeter, Devon EX1 2LU, UK.
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