Premium
Effects of Chronic Muscle Disuse on Skeletal Muscle Structure in Older Adults at the Tissue, Cellular and Molecular Levels
Author(s) -
Callahan Damien,
Tourville Timothy,
Miller Mark,
Slauterbeck James,
Savage Patrick,
Ades Philip,
Maughan David,
Beyn Bruce,
Toth Michael
Publication year - 2015
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.29.1_supplement.825.22
Subject(s) - skeletal muscle , vastus lateralis muscle , medicine , myofibril , sarcopenia , atrophy , muscle atrophy , myosin , myofilament , muscle hypertrophy , endocrinology , osteoarthritis , anatomy , myocyte , biology , pathology , biochemistry , alternative medicine
Physical inactivity promotes physical dysfunction and mobility disability. The goal of our study was to use a cross‐sectional approach to characterize the structural consequences of disuse, as well as evaluate potential effectors of skeletal muscle structure. Older adults with end‐stage knee osteoarthritis (OA), but no other acute/chronic illnesses, were used as a model of chronic muscle disuse and were compared to age‐, and health‐matched, recreationally active men and women (CON). Myofibrillar and cellular muscle structure was assessed from biopsies of the vastus lateralis and whole muscle size by computerized tomography. Significance was accepted at P<0.05) Quadriceps cross sectional area (CSA) was significantly lower in OA. Single fiber CSA was also reduced in OA for both MHC I, IIA and IIAX fibers. The effect of disuse on single fiber CSA in MHC IIAX fibers were greater in men than women. MHC isoform expression did not differ between groups, although the fractional distribution of MHC IIAX was elevated in single fibers in the OA group. No group differences were observed in myofilament fractional area, A‐band length. However, mitochondrial density correlated with habitual physical activity level (r=0.45). Our data suggest chronic muscle disuse is associated with potent muscle atrophy. Sex specific differences in atrophy of MHC IIAX fibers, which are more prevalent with disuse, may partially explain previously observed sex‐specific variation in muscle function at the single fiber level.