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Endurance training decreases the non-linearity in the VO2-power output relationship in humans.
MedLine Citation:
PMID:  22198015     Owner:  NLM     Status:  Publisher    
In this study we have hypothesised that 5-week cycling endurance training can decrease the magnitude of the non-proportional increase in VO2 to PO relationship (VO2 'excess') at exercise intensities exceeding the lactate threshold (LT). Ten untrained, physically active men performed an incremental cycling exercise until exhaustion before and after training. The mitochondrial DNA (mtDNA) copy number, myosin heavy chain composition (MyHC), uncoupling protein 3 (UCP3), as well as Ca2+ sarcoplasmic reticulum ATPases (SERCA) contents, were analyzed in muscle biopsies taken from v.lateralis before and after training. The training resulted in an enhancement of the power generating capabilities at maximal oxygen uptake (VO2max) by ~7% (P=0.002) despite there being no changes in VO2max (P=0.49). This effect was due to a considerable reduction in the magnitude of the VO2 'excess' (P<0.05) above the LT. A decrease in plasma ammonia concentration was found during exercise after training (P<0.05). A down-regulation of SERCA2 in v.lateralis (P=0.006) was observed after training. No changes in MyHC composition, selected electron transport chain proteins, UCP3 or in the mtDNA copy number (P>0.05) were found after training. We have concluded that the training-induced increase in power generating capabilities at VO2max was due to attenuation of the VO2 'excess' above the LT. This adaptive response seems to be related to the improvement of muscle metabolic stability as judged by a lowering of plasma ammonia concentration. The enhancement of muscle metabolic stability after training could be caused by a decrease in ATP usage at a given power output due to down-regulation of SERCA2 pumps.
Joanna Majerczak; Michal Korostynski; Zenon Nieckarz; Zbigniew Szkutnik; Krzysztof Duda; Jerzy A Zoladz
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-12-23
Journal Detail:
Title:  Experimental physiology     Volume:  -     ISSN:  1469-445X     ISO Abbreviation:  -     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2011-12-26     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1 University School of Physical Education, Krakow, Poland;
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