Although skeletal muscle work efficiency probably plays a key role in limiting mobility of the elderly, the physiological mechanisms responsible for this diminished function remain incompletely understood. Thus, in the quadriceps of young (n=9) and old (n=10) subjects, we measured the cost of muscle contraction (ATP cost) with 31P-magnetic resonance spectroscopy (31P-MRS) during (i) maximal intermittent contractions to elicit a metabolic demand from both cross-bridge cycling and ion pumping and (ii) a continuous maximal contraction to predominantly tax cross-bridge cycling. The ATP cost of the intermittent contractions was significantly greater in the old (0.30±0.22 mM·min−1·N·m−1) compared with the young (0.13±0.03 mM·min−1·N·m−1, P<0.05). In contrast, at the end of the continuous contraction protocol, the ATP cost in the old (0.10±0.07 mM·min−1·N·m−1) was not different from the young (0.06±0.02 mM·min−1·N·m−1, P=0.2). In addition, the ATP cost of the intermittent contractions correlated significantly with the single leg peak power of the knee-extensors assessed during incremental dynamic exercise (r=−0.55; P<0.05). Overall, this study reveals an age-related increase in the ATP cost of contraction, probably mediated by an excessive energy demand from ion pumping, which probably contributes to both the decline in muscle efficiency and functional capacity associated with aging.
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Research Article|
October 03 2014
Skeletal muscle work efficiency with age: the role of non-contractile processes
Gwenael Layec;
*Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah, U.S.A.
†Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah, U.S.A.
Correspondence: Dr Gwenael Layec (email [email protected]).
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Corey R. Hart;
Corey R. Hart
†Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah, U.S.A.
‡Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah, U.S.A.
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Joel D. Trinity;
Joel D. Trinity
*Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah, U.S.A.
†Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah, U.S.A.
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Yann Le Fur;
Yann Le Fur
§Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13385, Marseille, France
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Eun-Kee Jeong;
Eun-Kee Jeong
∥Department of Radiology and Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, U.S.A.
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Russell S. Richardson
Russell S. Richardson
*Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah, U.S.A.
†Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City, Utah, U.S.A.
‡Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah, U.S.A.
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Publisher: Portland Press Ltd
Received:
April 29 2014
Revision Received:
August 18 2014
Accepted:
August 19 2014
Accepted Manuscript online:
August 19 2014
Online ISSN: 1470-8736
Print ISSN: 0143-5221
© The Authors Journal compilation © 2015 Biochemical Society
2015
Clin Sci (Lond) (2015) 128 (3): 213–223.
Article history
Received:
April 29 2014
Revision Received:
August 18 2014
Accepted:
August 19 2014
Accepted Manuscript online:
August 19 2014
Citation
Gwenael Layec, Corey R. Hart, Joel D. Trinity, Yann Le Fur, Eun-Kee Jeong, Russell S. Richardson; Skeletal muscle work efficiency with age: the role of non-contractile processes. Clin Sci (Lond) 1 February 2015; 128 (3): 213–223. doi: https://doi.org/10.1042/CS20140274
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