Document Detail


Adaptation of the respiratory controller contributes to the attenuation of exercise hyperpnea in endurance-trained athletes.
MedLine Citation:
PMID:  21537929     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
We have reported that minute ventilation [[Formula: see text]] and end-tidal CO(2) tension [[Formula: see text]] are determined by the interaction between central controller and peripheral plant properties. During exercise, the controller curve shifts upward with unchanged central chemoreflex threshold to compensate for the plant curve shift accompanying increased metabolism. This effectively stabilizes [Formula: see text] within the normal range at the expense of exercise hyperpnea. In the present study, we investigated how endurance-trained athletes reduce this exercise hyperpnea. Nine exercise-trained and seven untrained healthy males were studied. To characterize the controller, we induced hypercapnia by changing the inspiratory CO(2) fraction with a background of hyperoxia and measured the linear [Formula: see text] relation [[Formula: see text]]. To characterize the plant, we instructed the subjects to alter [Formula: see text] voluntarily and measured the hyperbolic [Formula: see text] relation ([Formula: see text]). We characterized these relations both at rest and during light exercise. Regular exercise training did not affect the characteristics of either controller or plant at rest. Exercise stimulus increased the controller gain (S) both in untrained and trained subjects. On the other hand, the [Formula: see text]-intercept (B) during exercise was greater in trained than in untrained subjects, indicating that exercise-induced upward shift of the controller property was less in trained than in untrained subjects. The results suggest that the additive exercise drive to breathe was less in trained subjects, without necessarily a change in central chemoreflex threshold. The hyperbolic plant property shifted rightward and upward during exercise as predicted by increased metabolism, with little difference between two groups. The [Formula: see text] during exercise in trained subjects was 21% lower than that in untrained subjects (P < 0.01). These results indicate that an adaptation of the controller, but not that of plant, contributes to the attenuation of exercise hyperpnea at an iso-metabolic rate in trained subjects. However, whether training induces changes in neural drive originating from the central nervous system, afferents from the working limbs, or afferents from the heart, which is additive to the chemoreflex drive to breathe, cannot be determined from these results.
Authors:
Tadayoshi Miyamoto; Masashi Inagaki; Hiroshi Takaki; Toru Kawada; Toshiaki Shishido; Atsunori Kamiya; Masaru Sugimachi
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-5-3
Journal Detail:
Title:  European journal of applied physiology     Volume:  -     ISSN:  1439-6327     ISO Abbreviation:  -     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-5-3     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100954790     Medline TA:  Eur J Appl Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Faculty of Health Sciences, Morinomiya University of Medical Sciences, 1-26-16 Nanko-Kita, Suminoe-Ku, Osaka City, Osaka, 559-0034, Japan, miyamoto@morinomiya-u.ac.jp.
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