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Following lengthening contractions, force deficits of permeabilized single fibers from muscles of old women are greater than those from young women and are not reduced by training with shortening contractions
Author(s) -
Faulkner John A,
Larkin Lisa M,
Wellington Michael S,
Claflin Dennis R
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a383
Subject(s) - contraction (grammar) , medicine , muscle contraction , anatomy , chemistry
Following a severe strain of a maximally activated fiber, the force deficit provides an important measure of the susceptibility the fiber to contraction‐induced injury. Force deficits of single fibers from muscles of young and old humans have not been reported. Our hypotheses were that: (a) two 30% strains of maximally activated fast 2a fibers from vastus lateralis muscles of old women produce force deficits greater than those of young women and (b) 12 weeks of progressive resistance training of the knee extensor muscles with shortening contractions has no effect on the magnitude of the force deficit. Force deficits for fibers were 29.3±1.7% (n=11 fibers) for young and 39.6±3.0% (n=11) for old women. After 12 weeks of progressive resistance training with shortening contractions, the force deficit of fibers from muscles of old women of 39.2±1.5% (n=11) was not different from the pre‐training value. As with fast fibers from muscles of old mice and rats, those from old women were more susceptible to contraction‐induced injury and training with shortening contractions had no effect on the magnitude of the force deficit Supported by a grant from Michigan Life Sciences Corridor.