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The influence of exercise intensity on pulmonary oxygen uptake kinetics in young and late middle-aged adults.
MedLine Citation:
PMID:  22855280     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
It is unclear whether pulmonary oxygen uptake (VO(2)) kinetics demonstrate linear, first order behaviour during supra gas exchange threshold exercise. Resolution of this issue is pertinent to the elucidation of the factors regulating VO(2) kinetics, with oxygen availability and utilisation proposed as putative mediators. To re-examine this issue with the advantage of a relatively large sample size, fifty young (24±4 yrs) and fifteen late middle-aged (54±3 yrs) participants completed repeated bouts of moderate and heavy exercise. Pulmonary gas exchange, heart rate (HR) and cardiac output ("Q") variables were measured throughout. The phase II τ was slower during heavy exercise in both young (Mod: 22±9; Hvy: 29±9s; P≤0.001) and middle-aged (Mod: 22±9; Hvy: 30±8s; P≤0.001) individuals. The HR τ was slower during heavy exercise in young (Mod: 33±10; Hvy: 44±15s; P≤0.05) and middle-aged (Mod: 30±12; Hvy: 50±20s; P≤0.05) participants, and the "Q" τ showed a similar trend (Young - Mod: 21±13; Hvy: 28±16 s; Middle-aged - Mod: 32±13; Hvy: 40±15s; P≥0.05). There were no differences in primary component VO(2) kinetics between age groups but the middle-aged group had a significantly reduced VO(2) slow component amplitude in both absolute (Young: 0.25±0.09; Middle-aged: 0.11±0.06 l•min-1; P≤0.05) and relative terms (Young: 15±10; Middle-aged: 9±4%; P≤0.05). Thus, VO(2) kinetics do not demonstrate dynamic linearity during heavy intensity exercise. Speculatively, the slower phase II τ during heavy exercise might be attributable to reduced oxygen availability. Finally, the primary and slow components of VO(2) kinetics appear to be differentially influenced by middle-age.
Authors:
Melitta A McNarry; Michael I C Kingsley; Michael J Lewis
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-8-1
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  -     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-8-2     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1Swansea University.
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