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Improved single muscle fiber quality in the oldest-old.

Authors :
Grosicki, Greg J.
Standley, Robert A.
Murach, Kevin A.
Raue, Ulrika
Minchev, Kiril
Coen, Paul M.
Newman, Anne B.
Cummings, Steven
Harris, Tamara
Kritchevsky, Stephen
Goodpaster, Bret H.
Trappe, Scott
Source :
Journal of Applied Physiology; Oct2016, Vol. 121 Issue 4, p878-884, 7p
Publication Year :
2016

Abstract

We examined single muscle fiber contractile function of the oldest-old (3F/2M, 89 ± 1 yr old) enrolled in The Health, Aging, and Body Composition Study (The Health ABC Study). Vastus lateralis muscle biopsies were obtained and single muscle fiber function was determined (n = 105) prior to myosin heavy chain (MHC) isoform identification with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cross-sectional area of MHC I muscle fibers (5,576 ± 333 μm<superscript>2</superscript>; n = 58) was 21% larger (P < 0.05) than MHC IIa fibers (4,518 ± 386 μm<superscript>2</superscript>; n = 47). Normalized power (an indicator of muscle fiber quality incorporating size, strength, and speed) of MHC I and IIa muscle fibers was 2.3 ± 0.1 and 17.4 ± 0.8 W/l, respectively. Compared with previous research from our lab using identical procedures, MHC I normalized power was 28% higher than healthy 20 yr olds and similar to younger octogenarians (∼80 yr old). Normalized power of MHC IIa fibers was 63% greater than 20 yr olds and 39% greater than younger octogenarians. These comparative data suggest that power output per unit size (i.e., muscle quality) of remaining muscle fibers improves with age, a phenomenon more pronounced in MHC IIa fibers. Age-related single muscle fiber quality improvements may be a compensatory mechanism to help offset decrements in whole muscle function. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
87507587
Volume :
121
Issue :
4
Database :
Complementary Index
Journal :
Journal of Applied Physiology
Publication Type :
Academic Journal
Accession number :
118536347
Full Text :
https://doi.org/10.1152/japplphysiol.00479.2016