title: Aerobic exercise training improves whole muscle and single myofiber size and function in older women.
abstract: 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.
authors.affiliation: Human Performance Laboratory, Ball State University, Muncie Indiana 47306, USA. mharber@bsu.edu
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Harber
authors.forename: Adam R
authors.initials: AR
authors.lastname: Konopka
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Douglass
authors.forename: Kiril
authors.initials: K
authors.lastname: Minchev
authors.forename: Leonard A
authors.initials: LA
authors.lastname: Kaminsky
authors.forename: Todd A
authors.initials: TA
authors.lastname: Trappe
authors.forename: Scott
authors.initials: S
authors.lastname: Trappe
mesh_terms: D000368:Aged; D000375:Aging / Q000473:pathology / Q000502:physiology; D001706:Biopsy; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009119:Muscle Contraction / Q000502:physiology; D018656:Muscle Fibers, Fast-Twitch / Q000473:pathology* / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000473:pathology* / Q000502:physiology*; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000473:pathology* / Q000502:physiology*
chemical_list: D009124:Muscle Proteins
references.citation: J Physiol. 1993 Dec;472:595-614
references.pmid: 8145163
references.citation: J Neurol Sci. 1988 Apr;84(2-3):275-94
references.pmid: 3379447
references.citation: Clin Physiol Funct Imaging. 2002 May;22(3):169-72
references.pmid: 12076341
references.citation: J Appl Physiol (1985). 1989 Jan;66(1):465-75
references.pmid: 2917951
references.citation: Acta Physiol Scand. 2001 Dec;173(4):385-90
references.pmid: 11903130
references.citation: Am J Physiol Regul Integr Comp Physiol. 2007 Oct;293(4):R1722-7
references.pmid: 17670860
references.citation: J Appl Physiol (1985). 2008 Aug;105(2):629-36
references.pmid: 18535124
references.citation: J Appl Physiol (1985). 2000 Jul;89(1):143-52
references.pmid: 10904046
references.citation: Am J Physiol. 1996 Aug;271(2 Pt 1):C676-83
references.pmid: 8770009
references.citation: Am J Physiol Regul Integr Comp Physiol. 2002 Aug;283(2):R408-16
references.pmid: 12121854
references.citation: J Appl Physiol (1985). 1990 Nov;69(5):1725-33
references.pmid: 2272965
references.citation: J Physiol. 1981 Feb;311:201-18
references.pmid: 7264969
references.citation: J Appl Physiol (1985). 1992 May;72(5):1780-6
references.pmid: 1601786
references.citation: Can J Cardiol. 2005 Dec;21(14):1277-80
references.pmid: 16341296
references.citation: Med Sci Sports. 1976 Summer;8(2):96-100
references.pmid: 957938
references.citation: Am J Physiol Endocrinol Metab. 2004 Sep;287(3):E513-22
references.pmid: 15149953
references.citation: J Gerontol A Biol Sci Med Sci. 1996 May;51(3):B195-201
references.pmid: 8630695
references.citation: Am J Physiol Cell Physiol. 2001 Aug;281(2):C398-406
references.pmid: 11443039
references.citation: Am J Physiol Cell Physiol. 2005 Feb;288(2):C360-5
references.pmid: 15469952
references.citation: J Appl Physiol (1985). 1989 Jun;66(6):2844-9
references.pmid: 2745349
references.citation: Anal Biochem. 1983 Mar;129(2):277-87
references.pmid: 6189421
references.citation: J Physiol. 2003 Oct 1;552(Pt 1):47-58
references.pmid: 12837929
references.citation: Eur J Appl Physiol Occup Physiol. 1977 Oct 31;37(3):173-80
references.pmid: 913382
references.citation: J Physiol. 2008 Aug 1;586(15):3701-17
references.pmid: 18556367
references.citation: J Appl Physiol (1985). 1988 Mar;64(3):1038-44
references.pmid: 3366726
references.citation: Am J Physiol. 1994 Jun;266(6 Pt 1):C1699-1713
references.pmid: 8023900
references.citation: Diabetes Care. 2003 Nov;26(11):2977-82
references.pmid: 14578226
references.citation: Clin Nutr. 2006 Aug;25(4):573-80
references.pmid: 16330136
references.citation: Muscle Nerve. 2009 Apr;39(4):463-71
references.pmid: 19229964
references.citation: Am J Physiol. 1997 Nov;273(5 Pt 1):C1690-9
references.pmid: 9374656
references.citation: J Gerontol A Biol Sci Med Sci. 2006 May;61(5):480-7
references.pmid: 16720745
references.citation: Med Sci Sports Exerc. 2001 Jan;33(1):48-56
references.pmid: 11194111
references.citation: J Appl Physiol (1985). 2009 May;106(5):1611-7
references.pmid: 19246651
references.citation: Am J Physiol. 1997 Oct;273(4):E790-800
references.pmid: 9357810
references.citation: Circulation. 2007 Aug 28;116(9):1094-105
references.pmid: 17671236
references.citation: J Gerontol A Biol Sci Med Sci. 2002 Apr;57(4):B138-43
references.pmid: 11909878
references.citation: J Appl Physiol (1985). 2001 May;90(5):1663-70
references.pmid: 11299253
references.citation: J Appl Physiol (1985). 2006 Sep;101(3):721-7
references.pmid: 16614353
references.citation: J Appl Physiol (1985). 2007 Feb;102(2):634-40
references.pmid: 17095635
references.citation: J Appl Physiol (1985). 2001 Jun;90(6):2070-4
references.pmid: 11356767
references.citation: Acta Physiol (Oxf). 2007 Oct;191(2):147-59
references.pmid: 17655736
references.citation: Age Ageing. 1980 Aug;9(3):186-7
references.pmid: 7457275
references.citation: Am J Physiol. 1996 Aug;271(2 Pt 1):C666-75
references.pmid: 8770008
references.citation: J Physiol. 2004 Jun 1;557(Pt 2):501-13
references.pmid: 15064323
references.citation: Biochim Biophys Acta. 1971 Aug 6;245(1):259-62
references.pmid: 4332100
references.citation: J Appl Physiol (1985). 1990 May;68(5):1896-901
references.pmid: 2361892
references.citation: J Physiol. 1979 Jun;291:143-59
references.pmid: 314510
references.citation: J Appl Physiol. 1972 Sep;33(3):312-9
references.pmid: 4403464
references.citation: J Appl Physiol. 1976 Feb;40(2):149-54
references.pmid: 129449
references.citation: Eur J Appl Physiol. 2006 Jun;97(3):288-97
references.pmid: 16770464
references.citation: J Appl Physiol (1985). 1995 Jan;78(1):334-40
references.pmid: 7713834
references.citation: Diabetes. 2007 Jun;56(6):1615-22
references.pmid: 17351147
references.citation: Am J Physiol Regul Integr Comp Physiol. 2008 Mar;294(3):R939-47
references.pmid: 18094071
references.citation: Biophys J. 1987 Jul;52(1):127-31
references.pmid: 3607220
references.citation: J Appl Physiol (1985). 2006 Aug;101(2):531-44
references.pmid: 16614355
references.citation: Am J Physiol Endocrinol Metab. 2004 Jan;286(1):E92-101
references.pmid: 14506079
references.citation: Acta Physiol Scand. 1993 Aug;148(4):379-85
references.pmid: 8213193