title: Extracellular matrix remodeling and its contribution to protective adaptation following lengthening contractions in human muscle.
abstract: This study determined the contribution of extracellular matrix (ECM) remodeling to the protective adaptation of human skeletal muscle known as the repeated-bout effect (RBE). Muscle biopsies were obtained 3 hours, 2 days, and 27 days following an initial bout (B1) of lengthening contractions (LCs) and 2 days following a repeated bout (B2) in 2 separate studies. Biopsies from the nonexercised legs served as controls. In the first study, global transcriptomic analysis indicated widespread changes in ECM structural, deadhesive, and signaling transcripts, 3 hours following LC. To determine if ECM remodeling is involved in the RBE, we conducted a second study by use of a repeated-bout paradigm. TNC immunoreactivity increased 10.8-fold following B1, was attenuated following B2, and positively correlated with LC-induced strength loss (r(2) = 0.45; P = 0.009). Expression of collagen I, III, and IV (COL1A1, COL3A1, COL4A1) transcripts was unchanged early but increased 5.7 ± 2.5-, 3.2 ± 0.9-, and 2.1 ± 0.4-fold (P < 0.05), respectively, 27 days post-B1 and were unaffected by B2. Likewise, TGF-β signaling demonstrated a delayed response following LC. Satellite cell content increased 80% (P < 0.05) 2 days post-B1 (P < 0.05), remained elevated 27 days post-B1, and was unaffected by B2. Collectively, the data suggest sequential ECM remodeling characterized by early deadhesion and delayed reconstructive activity that appear to contribute to the RBE.
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA robhyldahl@byu.edu.
authors: Robert D
authors: RD
authors: Hyldahl
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA.
authors: Brad
authors: B
authors: Nelson
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA.
authors: Ling
authors: L
authors: Xin
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA.
authors: Tyson
authors: T
authors: Welling
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA.
authors: Logan
authors: L
authors: Groscost
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA.
authors: Monica J
authors: MJ
authors: Hubal
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA.
authors: Stuart
authors: S
authors: Chipkin
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA.
authors: Priscilla M
authors: PM
authors: Clarkson
authors: *Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA; Department of Natural Sciences, Ohio Dominican University, Columbus, Ohio, USA; Department of Kinesiology, University of Massachusetts Amherst, Massachusetts, USA; and Department of Integrative Systems Biology, George Washington University, Washington, DC, USA.
authors: Allen C
authors: AC
authors: Parcell
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000328:Adult; D003094:Collagen / Q000235:genetics; D005109:Extracellular Matrix / Q000235:genetics / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007797:Laminin / Q000235:genetics; D008297:Male; D009119:Muscle Contraction / Q000235:genetics / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism; D019063:Tenascin / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D055815:Young Adult
chemical_list: D007797:Laminin; D012333:RNA, Messenger; D019063:Tenascin; D016212:Transforming Growth Factor beta; D003094:Collagen
keywords: eccentric exercise; muscle damage; repeated-bout effect; satellite cell