title: Strength, [corrected] endurance or combined training elicit diverse skeletal muscle myosin heavy chain isoform proportion but unaltered androgen receptor concentration in older men.
abstract: We investigated whether the myosin heavy chain (MyHC) proportion and androgen receptor (AR) concentration in skeletal muscle differ following 21 weeks of strength, endurance and combined training in untrained older men. Strength (S) and endurance (E) groups trained twice per week and combined (S+E) group trained four times per week (two strength and two endurance). Muscle biopsies were obtained before and after the training period from m. vastus lateralis (VL) and AR mRNA and protein concentration and MyHC proportion were determined. 1RM increased during the training period in S, S+E and E but the changes were greater in S and S+E than in E. Statistically significant increases were observed only in S and S+E in maximal isometric force as well as in VL thickness. VO (2max) increased significantly only in E. MyHCIIa proportion increased in S, while MyHCIIa proportion decreased and MyHCI increased (p<0.05) in E. No statistically significant changes were observed in serum testosterone and in AR mRNA or protein concentrations. The present results indicate that 21 weeks of strength, endurance or combined training changed MyHC proportion according to the training method but did not have an effect on AR mRNA or protein expression in skeletal muscle at rest.
authors.affiliation: Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland. juha.ahtiainen@jyu.fi
authors.forename: J P
authors.initials: JP
authors.lastname: Ahtiainen
authors.forename: J J
authors.initials: JJ
authors.lastname: Hulmi
authors.forename: W J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: M
authors.initials: M
authors.lastname: Lehti
authors.forename: A
authors.initials: A
authors.lastname: Pakarinen
authors.forename: A A
authors.initials: AA
authors.lastname: Mero
authors.forename: L
authors.initials: L
authors.lastname: Karavirta
authors.forename: E
authors.initials: E
authors.lastname: Sillanpää
authors.forename: H
authors.initials: H
authors.lastname: Selänne
authors.forename: M
authors.initials: M
authors.lastname: Alen
authors.forename: J
authors.initials: J
authors.lastname: Komulainen
authors.forename: V
authors.initials: V
authors.lastname: Kovanen
authors.forename: K
authors.initials: K
authors.lastname: Nyman
authors.forename: K
authors.initials: K
authors.lastname: Häkkinen
mesh_terms: D000368:Aged; D015444:Exercise / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D052097:Quadriceps Muscle / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism*; D055070:Resistance Training / Q000379:methods*; D013739:Testosterone / Q000097:blood
chemical_list: D012333:RNA, Messenger; D011944:Receptors, Androgen; D013739:Testosterone; D018995:Myosin Heavy Chains