Document Detail


Non-invasive estimation of microvascular O2 provision during exercise on-transients in healthy young males.
MedLine Citation:
PMID:  22914753     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Two methods for estimating changes in microvascular O(2) delivery during the on-transient of exercise were evaluated. They were tested to assess the role of the adjustment of the estimated microvascular O(2) delivery in the speeding of VO(2) kinetics during a Mod1-Hvy-Mod2 protocol (Mod, moderate-intensity exercise; Hvy, heavy-intensity 'priming' exercise) in which Mod2 is preceded by a bout of Hvy. Mod pulmonary VO(2) (VO(2p)) and deoxy-hemoglobin [HHb] data were collected in 12 males (23 ± 3 yr); response profiles were fit with a mono-exponential. Signals were also: a) scaled to a relative % of the response (0-100%) to calculate the [HHb]/VO(2) ratio for each individual; b) re-arranged in the Fick equation for estimation of capillary blood flow (Q(cap)). A transient [HHb]/VO(2) "overshoot" observed in Mod1 (1.06±0.05; p<0.05) was absent during Mod2 (1.01±0.06; p>0.05); reductions in the [HHb]/VO(2) ratio (Mod1 - Mod2) were related to reductions in phase II τVO(2p) (r=0.82; p<0.05). For Q(cap), a near-exponential response was observed in 8/12 subjects in Mod1 and only in 4/12 subjects in Mod2. The Q(cap) profile was shown to be highly dependent on the [HHb] baseline-to-amplitude ratio. Thus, accurate and physiologically consistent estimations of Q(cap) were not possible in most cases. This study confirmed that 'priming' exercise results in an improved O2 delivery as shown by the decreased [HHb]/VO(2) ratio that was related to the smaller τVO(2) in Mod2. Additionally, this study suggested that Q(cap) analysis may not be valid and should be interpreted with caution when assessing microvascular delivery of O(2).
Authors:
Juan M Murias; Matthew D Spencer; Silvia Pogliaghi; Donald H Paterson
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-8-22
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:  2012-8-23     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:
1The University of Western Ontario.
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