Tags

Type your tag names separated by a space and hit enter

Reduction in hybrid single muscle fiber proportions with resistance training in humans.
J Appl Physiol (1985). 2001 Nov; 91(5):1955-61.JA

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- and post-PRT muscle biopsies from the right vastus lateralis for single muscle fiber 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 protocol elicited 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 + I/IIa/IIx + IIa/IIx) decreased (Delta = -19 and -30 for YM and YW, respectively; P < 0.05) with the training, as did the MHC IIx distribution (Delta = -2; YW only; P < 0.05). Alterations in the 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 approximately 7% 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.

Authors+Show Affiliations

Human Performance Laboratory, Ball State University, Muncie, Indiana 47306, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

11641330

Citation

Williamson, D L., et al. "Reduction in Hybrid Single Muscle Fiber Proportions With Resistance Training in Humans." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 91, no. 5, 2001, pp. 1955-61.
Williamson DL, Gallagher PM, Carroll CC, et al. Reduction in hybrid single muscle fiber proportions with resistance training in humans. J Appl Physiol (1985). 2001;91(5):1955-61.
Williamson, D. L., Gallagher, P. M., Carroll, C. C., Raue, U., & Trappe, S. W. (2001). Reduction in hybrid single muscle fiber proportions with resistance training in humans. Journal of Applied Physiology (Bethesda, Md. : 1985), 91(5), 1955-61.
Williamson DL, et al. Reduction in Hybrid Single Muscle Fiber Proportions With Resistance Training in Humans. J Appl Physiol (1985). 2001;91(5):1955-61. PubMed PMID: 11641330.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Reduction in hybrid single muscle fiber proportions with resistance training in humans. AU - Williamson,D L, AU - Gallagher,P M, AU - Carroll,C C, AU - Raue,U, AU - Trappe,S W, PY - 2001/10/20/pubmed PY - 2002/1/5/medline PY - 2001/10/20/entrez SP - 1955 EP - 61 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J Appl Physiol (1985) VL - 91 IS - 5 N2 - 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- and post-PRT muscle biopsies from the right vastus lateralis for single muscle fiber 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 protocol elicited 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 + I/IIa/IIx + IIa/IIx) decreased (Delta = -19 and -30 for YM and YW, respectively; P < 0.05) with the training, as did the MHC IIx distribution (Delta = -2; YW only; P < 0.05). Alterations in the 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 approximately 7% 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. SN - 8750-7587 UR - https://www.unboundmedicine.com/medline/citation/11641330/Reduction_in_hybrid_single_muscle_fiber_proportions_with_resistance_training_in_humans_ L2 - https://journals.physiology.org/doi/10.1152/jappl.2001.91.5.1955?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -