title: Why do we suffer more ACL injuries in the cold? A pilot study into potential risk factors.
abstract: OBJECTIVE
  This study aimed to investigate temperature-related changes in different neuro-muscular parameters, to elucidate the reasons for the increased likeliness of injuries of the anterior cruciate ligament under cold environmental conditions.
  
  
  METHODS
  Repeated measures study design.
  
  
  METHODS
  To induce peripheral cooling of the knee joint and thigh muscles, ten healthy, female subjects underwent 30 min of exposure to a cold environment. Both knee extensor and flexor muscles were examined for electromyographic activity, maximum voluntary contraction strength, rate of force development and force sense. Measures of knee laxity were obtained by computerized arthrometry.
  
  
  RESULTS
  Following cold exposure, rate of force development of the knee flexor muscles was significantly reduced (p = 0.016). Left-shifts of electromyography power spectra indicated changes in neural drive to the medial and lateral head of the vastus muscle. Maximum strength, force sense and knee laxity were not affected by the intervention.
  
  
  CONCLUSIONS
  The reduced capacity of cold knee flexor muscles to explosively generate force may limit the hamstrings' capability to counter strong and fast contractions of the knee extensor muscles that cause anterior shear force on the tibia and, thus, strain the anterior cruciate ligament.
authors.affiliation: Department of Sport Science, University of Innsbruck, Fürstenweg 185, Innsbruck, Austria. Electronic address: robert.csapo@uibk.ac.at.
authors.forename: Robert
authors.initials: R
authors.lastname: Csapo
authors.affiliation: Department of Sport Science, University of Innsbruck, Fürstenweg 185, Innsbruck, Austria.
authors.forename: Ramona
authors.initials: R
authors.lastname: Folie
authors.affiliation: Centre of Technology of Ski and Alpine Sport, Fürstenweg 187, Innsbruck, Austria.
authors.forename: Simona
authors.initials: S
authors.lastname: Hosp
authors.affiliation: Centre of Technology of Ski and Alpine Sport, Fürstenweg 187, Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Hasler
authors.affiliation: Department of Sport Science, University of Innsbruck, Fürstenweg 185, Innsbruck, Austria.
authors.forename: Werner
authors.initials: W
authors.lastname: Nachbauer
mesh_terms: D000070598:Anterior Cruciate Ligament Injuries / Q000503:physiopathology*; D003080:Cold Temperature; D004576:Electromyography; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology; D007719:Knee Joint / Q000503:physiopathology; D010865:Pilot Projects; D011434:Proprioception / Q000502:physiology; D012307:Risk Factors; D055815:Young Adult
keywords: Knee laxity; Peripheral cooling; Proprioception; Rate of force development