| Power loss is greater following lengthening contractions in old versus young women. | |
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MedLine Citation:
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PMID: 21559865 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Compared with isometric and dynamic velocity-constrained (isokinetic) tasks, less is known regarding velocity-dependent (isotonic) muscle power and recovery in older adults following repeated fatiguing lengthening contractions. We investigated voluntary and evoked neuromuscular properties of the dorsiflexors in nine old (68.3 ± 6.1 years) and nine young women (25.1 ± 1.3 years) during and following 150 lengthening contractions for up to 30 min of recovery. At baseline, the old were ~21% weaker for maximum isometric voluntary contraction (MVC) torque (P < 0.05), ~21% slower for peak loaded shortening velocity (P < 0.05), and ~39% less powerful compared with the young (P < 0.05). Following the task, MVC torque was depressed equally (~28%) for both groups (P < 0.05), but power was reduced ~19% in the old and only ~8% in the young (P < 0.05). Both measures remained depressed during the 30-min recovery period. Peak twitch torque (P (t)) was ~50% lower in the old at task termination, whereas the young were unchanged. However, by 5 min of recovery, P (t) was reduced similarly (~50%) in both groups, and neither recovered by 30 min. The old were affected more by low-frequency torque depression than the young, as shown by the ~40% and ~20% decreases in the stimulated 10:50 Hz ratio at task termination respectively, whereas both groups were affected similarly (~50%) 5 min into recovery, and neither recovered by 30 min. Thus, the coexistence of fatigue and muscle damage induced by the repetitive lengthening contractions impaired excitation-contraction coupling and cross-bridge function to a greater extent in the old, leading to a more pronounced initial loss of power than the young for up to 10 min following the exercise However, power remained blunted in both groups during the 30-min recovery period. These results indicate that older women are more susceptible to power loss than young following lengthening contractions, likely owing to a greater impairment in calcium kinetics. |
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Authors:
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Geoffrey A Power; Brian H Dalton; Charles L Rice; Anthony A Vandervoort |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-5-11 |
Journal Detail:
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Title: Age (Dordrecht, Netherlands) Volume: - ISSN: 1574-4647 ISO Abbreviation: - Publication Date: 2011 May |
Date Detail:
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Created Date: 2011-5-11 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101250497 Medline TA: Age (Dordr) Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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