title: Alterations in neuromuscular function in girls with generalized joint hypermobility.
abstract: Generalized Joint Hypermobility (GJH) is associated with increased risk of musculoskeletal joint pain. We investigated neuromuscular performance and muscle activation strategy.
  
  
  
  Girls with GJH and non-GJH (NGJH) performed isometric knee flexions (90°,110°,130°), and extensions (90°) at 20 % Maximum Voluntary Contraction, and explosive isometric knee flexions while sitting. EMG was recorded from knee flexor and extensor muscles.
  
  
  
  Early rate of torque development was 53 % faster for GJH. Reduced hamstring muscle activation in girls with GJH was found while knee extensor and calf muscle activation did not differ between groups. Flexion-extension and medial-lateral co-activation ratio during flexions were higher for girls with GJH than NGJH girls.
  
  
  
  Girls with GJH had higher capacity to rapidly generate force than NGJH girls which may reflect motor adaptation to compensate for hypermobility. Higher medial muscle activation indicated higher levels of medial knee joint compression in girls with GJH. Increased flexion-extension co-activation ratios in GJH were explained by decreased agonist drive to the hamstrings.
authors.affiliation: Department of Nutrition, Exercise and Sport, Integrative Physiology, Biomechanics and Motor Control Laboratory, University of Copenhagen, Copenhagen, Denmark. brjensen@nexs.ku.dk.|Department of Neurology, Odense University Hospital, University of Southern Denmark, Odense, Denmark. brjensen@nexs.ku.dk.
authors.forename: Bente Rona
authors.initials: BR
authors.lastname: Jensen
authors.affiliation: Department of Nutrition, Exercise and Sport, Integrative Physiology, Biomechanics and Motor Control Laboratory, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Sandfeld
authors.affiliation: Department of Nutrition, Exercise and Sport, Integrative Physiology, Biomechanics and Motor Control Laboratory, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Pia Sandfeld
authors.initials: PS
authors.lastname: Melcher
authors.affiliation: Research Unit for Musculoskeletal Function and Physiotherapy, Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors.forename: Katrine Lyders
authors.initials: KL
authors.lastname: Johansen
authors.affiliation: Department of Nutrition, Exercise and Sport, Integrative Physiology, Biomechanics and Motor Control Laboratory, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Hendriksen
authors.affiliation: Research Unit for Musculoskeletal Function and Physiotherapy, Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.|Department of Health Sciences, Institute of Occupational Therapy, Physiotherapy and Radiography, Bergen University College, Bergen, Norway.
authors.forename: Birgit
authors.initials: B
authors.lastname: Juul-Kristensen
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D018771:Arthralgia / Q000209:etiology; D015331:Cohort Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007593:Joint Instability / Q000150:complications / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016059:Range of Motion, Articular; D019415:Torque
keywords: EMG; Hypermobile; Knee; Muscle activation; Rate of force development