title: Muscle atrophy, voluntary activation disturbances, and low serum concentrations of IGF-1 and IGFBP-3 are associated with weakness in people with chronic stroke.
abstract: BACKGROUND
  The muscle weakness that is exhibited poststroke is due to a multifactorial etiology involving the central nervous system and skeletal muscle changes. Insulinlike growth factor 1 (IGF-1) and IGF binding protein 3 (IGFBP-3) have been described as biomarkers of neuromuscular performance in many conditions. However, no information about these biomarkers is available for people with chronic hemiparesis.
  
  
  OBJECTIVE
  The purpose of this study was to investigate possible factors involved in muscle weakness, such as IGF-1 and IGFBP-3 serum concentrations, muscle volume, and neuromuscular performance of the knee flexors and extensors, in people with chronic hemiparesis poststroke.
  
  
  METHODS
  This was a cross-sectional study.
  
  
  METHODS
  A cross-sectional study was performed on 14 individuals poststroke who were paired with healthy controls. Mobility, function, balance, and quality of life were recorded as outcome measures. Knee flexor and extensor muscle volumes and neuromuscular performance were measured using nuclear magnetic resonance imaging, dynamometry, and electromyography. The serum concentrations of IGF-1 and IGFBP-3 were quantified by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  The hemiparetic group had low serum concentrations of IGF-1 (25%) and IGFBP-3 (40%); reduced muscle volume in the vastus medialis (32%), vastus intermedius (29%), biceps femoris (16%), and semitendinosus and semimembranosus (12%) muscles; reduced peak torque, power, and work of the knee flexors and extensors; and altered agonist and antagonist muscle activation compared with controls.
  
  
  CONCLUSIONS
  Low serum concentrations of IGF-1 and IGFBP-3, deficits in neuromuscular performance, selective muscle atrophy, and decreased agonist muscle activation were found in the group with chronic hemiparesis poststroke. Both hemorrhagic and ischemic stroke were considered, and the data reflect a chronic poststroke population with good function.
authors.affiliation: M.A. Silva-Couto, MS, Department of Physical Therapy, Federal University of São Carlos, Rodovia Washington Luis, Km 235, Monjolinho, São Carlos, São Paulo, Brazil 13565-905. marcela.deabreu@yahoo.com.br russo@ufscar.br thiagoluizrusso@gmail.com.
authors.forename: Marcela de Abreu
authors.initials: Mde A
authors.lastname: Silva-Couto
authors.affiliation: C.L. Prado-Medeiros, PhD, Department of Physical Therapy, Federal University of São Carlos.
authors.forename: Christiane Lanatovitz
authors.initials: CL
authors.lastname: Prado-Medeiros
authors.affiliation: A.B. Oliveira, PhD, Department of Physical Therapy, Federal University of São Carlos.
authors.forename: Ana Beatriz
authors.initials: AB
authors.lastname: Oliveira
authors.affiliation: C.C. Alcântara, MS, Department of Physical Therapy, Federal University of São Carlos.
authors.forename: Carolina Carmona
authors.initials: CC
authors.lastname: Alcântara
authors.affiliation: A.T. Guimarães, Department of Physical Therapy, Federal University of São Carlos.
authors.forename: Araci Teixeira
authors.initials: AT
authors.lastname: Guimarães
authors.affiliation: T.F. Salvini, PhD, Department of Physical Therapy, Federal University of São Carlos.
authors.forename: Tania de Fatima
authors.initials: Tde F
authors.lastname: Salvini
authors.affiliation: R. Mattioli, PhD, Department of Physical Therapy, Federal University of São Carlos.
authors.forename: Rosana
authors.initials: R
authors.lastname: Mattioli
authors.affiliation: T.L. Russo, PhD, Laboratório de Pesquisa em Fisioterapia Neurológica (LaFiN) and Department of Physical Therapy, Federal University of São Paulo, Rodovia Washington Luis, Km 235, Monjolinho, São Carlos, São Paulo, Brazil 13565-905. marcela.deabreu@yahoo.com.br russo@ufscar.br thiagoluizrusso@gmail.com.
authors.forename: Thiago Luiz
authors.initials: TL
authors.lastname: de Russo
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007717:Knee / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D053581:Muscle Strength Dynamometer; D009133:Muscular Atrophy / Q000097:blood* / Q000209:etiology / Q000503:physiopathology; D010291:Paresis / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D004856:Postural Balance; D052097:Quadriceps Muscle / Q000473:pathology / Q000503:physiopathology*; D011788:Quality of Life; D020521:Stroke / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D019415:Torque; D016138:Walking
chemical_list: D015415:Biomarkers; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I