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Titolo:
Reduction in hybrid single muscle fiber proportions with resistance training in humans
Autore:
Williamson, DL; Gallagher, PM; Carroll, CC; Raue, U; Trappe, SW;
Indirizzi:
Ball State Univ, Human Performance Lab, Muncie, IN 47306 USA Ball State Univ Muncie IN USA 47306 Performance Lab, Muncie, IN 47306 USA
Titolo Testata:
JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 5, volume: 91, anno: 2001,
pagine: 1955 - 1961
SICI:
8750-7587(2001)91:5<1955:RIHSMF>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
HUMAN SKELETAL-MUSCLE; HEAVY-CHAIN ISOFORMS; OLDER MEN; STRENGTH; COEXPRESSION; ADAPTATIONS; WOMEN;
Keywords:
coexpressed fiber; aging; skeletal muscle; fiber type; progressive resistance training;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Trappe, SW Ball State Univ, Human Performance Lab, Muncie, IN 47306 USA Ball State Univ Muncie IN USA 47306 Lab, Muncie, IN 47306 USA
Citazione:
D.L. Williamson et al., "Reduction in hybrid single muscle fiber proportions with resistance training in humans", J APP PHYSL, 91(5), 2001, pp. 1955-1961

Abstract

The purpose of this investigation was to examine the effects of 12 wk of progressive resistance training (PRT) on single muscle fiber myosin heavy chain (MHC; I, I/IIa, I/IIa/IIx, IIa, IIa/IIx, IIx) isoform proportions in young individuals. Young, untrained men (YM; n = 6) and women (YW; n = 6) (age = 22 +/- 1 and 25 +/- 2 yr for YW and YM, respectively) received pre- andpost-PRT muscle biopsies from the right vastus lateralis for single musclefiber MHC distribution by electrophoretic analysis (192 +/- 5 pre- and 183+/- 6 post-fibers/subject analyzed; 4,495 fibers total). Data are presented as percentages of the total fibers analyzed per subject. The PRT protocolelicited an increase in the pure MHC IIa (Delta = +24 and + 27; YW and YM,respectively; P< 0.05) with no change in the pure MHC I distribution. The hybrid MHC distributions decreased I/IIa/ IIx (<Delta> = -2; YM and YW; P< 0.05), IIa/IIx (<Delta> = -13 and -19 for YM and YW, respectively; P< 0.05), and total hybrid fiber proportion (I/IIa 1 I/IIa/ IIx 1 IIa/IIx) decreased (D 5 -19 and -30 for YM and YW, respectively; P< 0.05) with the training,as did the MHC IIx distribution (D 5 22; YW only; P< 0.05). Alterations inthe predominance of MHC isoforms within hybrid fibers (decrease in MHC I-dominant I/IIa and nondominant MHC IIa/IIx, increase in MHC IIa-dominant IIa/IIx; P< 0.05) appeared to contribute to the increase in the MHC IIa proportion. Electrophoresis of muscle cross sections revealed an similar to7% increase (P< 0.05) in MHC IIa proportion in both groups, whereas the MHC IIx decrease by 7.5 and 11.6% post-PRT in YW and YM, respectively. MHC I proportions increase in YM by 4.8% (P< 0.05) post-PRT. These findings further support previous resistance training data in young adults with respect to the increase in the MHC IIa proportions but demonstrate that a majority of the change can be attributed to the decrease in single-fiber hybrid proportions.

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Documento generato il 29/03/20 alle ore 09:05:31