title: Myosin heavy chain plasticity in aging skeletal muscle with aerobic exercise training.
abstract: To assess myosin heavy chain (MHC) plasticity in aging skeletal muscle with aerobic exercise training, MHC composition was measured at the messenger RNA (mRNA) level and protein level in mixed-muscle homogenates and single myofibers. Muscle samples were obtained from eight nonexercising women (70 ± 2 years) before and after 12 weeks of training (20-45 minutes of cycle exercise per session at 60%-80% heart rate reserve, three to four sessions per week). Training elevated MHC I mRNA (p < .10) and protein (p < .05) in mixed-muscle (54% ± 4% to 61% ± 2%) and single myofibers (42% ± 4% to 52% ± 3%). The increase in MHC I protein was positively correlated (p < .05) with improvements in whole muscle power. Training resulted in a general downregulation of MHC IIa and IIx at the mRNA and protein levels. The training-induced increase in MHC I protein and mRNA demonstrates the maintenance of skeletal muscle plasticity with aging. Furthermore, these data suggest that a shift toward an oxidative MHC phenotype may be beneficial for metabolic and functional health in older individuals.
authors.affiliation: Human Performance Laboratory, Ball State University, Muncie, IN 47306, USA.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Konopka
authors.forename: Todd A
authors.initials: TA
authors.lastname: Trappe
authors.forename: Bozena
authors.initials: B
authors.lastname: Jemiolo
authors.forename: Scott W
authors.initials: SW
authors.lastname: Trappe
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Harber
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism*; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D006801:Humans; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D010806:Physical Education and Training; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; D018995:Myosin Heavy Chains