title: Greater intracortical inhibition associates with lower quadriceps voluntary activation in individuals with ACL reconstruction.
abstract: Decreased voluntary activation contributes to quadriceps weakness following anterior cruciate ligament reconstruction (ACLR). Alterations in neural excitability are likely responsible for reductions in quadriceps voluntary activation, and may be due to specific alterations in intracortical inhibition and facilitation. Therefore, we sought to determine if intracortical inhibition (SICI) and intracortical facilitation (ICF) associate with quadriceps voluntary activation in individuals with ACLR. Twenty-seven participants with a primary, unilateral ACLR were enrolled in this study. Bilateral central activation ratio (CAR) and paired-pulse transcranial magnetic stimulation were used to assess quadriceps voluntary activation, as well as SICI and ICF in the vastus medalis, respectively. Pearson Product Moment correlations were used to determine the association between CAR and (1) SICI, and (2) ICF in each limb. Lesser CAR associated with lesser SICI amplitude (r = 0.502, P = 0.008) in the ACLR limb. No associations in the contralateral limb were significant. Our results suggest greater intracortical inhibition associates with lesser voluntary activation in individuals with ACL. Implementing interventions that target intracortical inhibition may aid in restoring quadriceps voluntary activation following ACLR.
authors.affiliation: Human Movement Science Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. bluc@live.unc.edu.|Department of Exercise and Sports Science, University of North Carolina at Chapel Hill, 209 Fetzer Hall, CB#8700, Chapel Hill, NC, 27599-8700, USA. bluc@live.unc.edu.
authors.forename: Brittney A
authors.initials: BA
authors.lastname: Luc-Harkey
authors.affiliation: Human Movement Science Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.|Department of Exercise and Sports Science, University of North Carolina at Chapel Hill, 209 Fetzer Hall, CB#8700, Chapel Hill, NC, 27599-8700, USA.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Harkey
authors.affiliation: Department of Kinesiology, California State University, Fullerton, USA.
authors.forename: Derek N
authors.initials: DN
authors.lastname: Pamukoff
authors.affiliation: Department of Exercise and Sports Science, University of North Carolina at Chapel Hill, 209 Fetzer Hall, CB#8700, Chapel Hill, NC, 27599-8700, USA.
authors.forename: Rebecca H
authors.initials: RH
authors.lastname: Kim
authors.affiliation: Department of Exercise and Sports Science, University of North Carolina at Chapel Hill, 209 Fetzer Hall, CB#8700, Chapel Hill, NC, 27599-8700, USA.
authors.forename: Troy K
authors.initials: TK
authors.lastname: Royal
authors.affiliation: Department of Exercise and Sports Science, University of North Carolina at Chapel Hill, 209 Fetzer Hall, CB#8700, Chapel Hill, NC, 27599-8700, USA.
authors.forename: J Troy
authors.initials: JT
authors.lastname: Blackburn
authors.affiliation: Department of Orthopaedics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Jeffery T
authors.initials: JT
authors.lastname: Spang
authors.affiliation: Department of Exercise and Sports Science, University of North Carolina at Chapel Hill, 209 Fetzer Hall, CB#8700, Chapel Hill, NC, 27599-8700, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Pietrosimone
mesh_terms: D000293:Adolescent; D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction / Q000009:adverse effects*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005121:Extremities / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D009433:Neural Inhibition / Q000502:physiology*; D011183:Postoperative Complications / Q000473:pathology*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Active motor threshold; Central activation ratio; Intracortical facilitation; Quadriceps strength; Transcranial magnetic stimulation