Document Detail

Aerobic exercise training improves whole muscle and single myofiber size and function in older women.
MedLine Citation:
PMID:  19692660     Owner:  NLM     Status:  MEDLINE    
To comprehensively assess the influence of aerobic training on muscle size and function, we examined seven older women (71 +/- 2 yr) before and after 12 wk of cycle ergometer training. The training program increased (P < 0.05) aerobic capacity by 30 +/- 6%. Quadriceps muscle volume, determined by magnetic resonance imaging (MRI), was 12 +/- 2% greater (P < 0.05) after training and knee extensor power increased 55 +/- 7% (P < 0.05). Muscle biopsies were obtained from the vastus lateralis to determine size and contractile properties of individual slow (MHC I) and fast (MHC IIa) myofibers, myosin light chain (MLC) composition, and muscle protein concentration. Aerobic training increased (P < 0.05) MHC I fiber size 16 +/- 5%, while MHC IIa fiber size was unchanged. MHC I peak power was elevated 21 +/- 8% (P < 0.05) after training, while MHC IIa peak power was unaltered. Peak force (Po) was unchanged in both fiber types, while normalized force (Po/cross-sectional area) was 10% lower (P < 0.05) for both MHC I and MHC IIa fibers after training. The decrease in normalized force was likely related to a reduction (P < 0.05) in myofibrillar protein concentration after training. In the absence of an increase in Po, the increase in MHC I peak power was mediated through an increased (P < 0.05) maximum contraction velocity (Vo) of MHC I fibers only. The relative proportion of MLC(1s) (Pre: 0.62 +/- 0.01; Post: 0.58 +/- 0.01) was lower (P < 0.05) in MHC I myofibers after training, while no differences were present for MLC(2s) and MLC(3f) isoforms. These data indicate that aerobic exercise training improves muscle function through remodeling the contractile properties at the myofiber level, in addition to pronounced muscle hypertrophy. Progressive aerobic exercise training should be considered a viable exercise modality to combat sarcopenia in the elderly population.
Matthew P Harber; Adam R Konopka; Matthew D Douglass; Kiril Minchev; Leonard A Kaminsky; Todd A Trappe; Scott Trappe
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2009-08-19
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  297     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-11-02     Completed Date:  2009-12-03     Revised Date:  2013-12-25    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R1452-9     Citation Subset:  IM    
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MeSH Terms
Aging / pathology,  physiology
Exercise / physiology*
Exercise Test
Magnetic Resonance Imaging
Muscle Contraction / physiology
Muscle Fibers, Fast-Twitch / pathology*,  physiology*
Muscle Fibers, Slow-Twitch / pathology*,  physiology*
Muscle Proteins / metabolism
Muscle, Skeletal / pathology*,  physiology*
Grant Support
AG032127/AG/NIA NIH HHS; R15 AG032127-01A2/AG/NIA NIH HHS
Reg. No./Substance:
0/Muscle Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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