title: Persistence of long term isokinetic strength deficits in subjects with lateral ankle sprain as measured with a protocol including maximal preloading.
abstract: BACKGROUND
  The assessment of muscle function is a cornerstone in the management of subjects who have sustained a lateral ankle sprain. The ankle range of motion being relatively small, the use of preloading allows to measure maximal strength throughout the whole amplitude and therefore to better characterize ankle muscles weaknesses. This study aimed to assess muscle strength of the injured and uninjured ankles in subjects with a lateral ankle sprain, to document the timeline of strength recovery, and to determine the influence of sprain grade on strength loss.
  
  
  METHODS
  Maximal torque of the periarticular muscles of the ankle in a concentric mode using a protocol with maximal preloading was tested in 32 male soldiers at 8 weeks and 6 months post-injury.
  
  
  RESULTS
  The evertor muscles of the injured ankles were weaker than the uninjured ones at 8 weeks and 6 months post-injury (P<0.0001, effect size=0.31-0.42). Muscle weaknesses also persisted in the plantarflexors of the injured ankles at 8 weeks (P=0.0014, effect size=0.52-0.58) while at 6 months, only the subjects with a grade II sprain displayed such weaknesses (P<0.0001, effect size 0.27-0.31). The strength of the invertor and dorsiflexor muscles did not differ between sides.
  
  
  CONCLUSIONS
  The use of an isokinetic protocol with preloading demonstrates significant but small strength deficits in the evertor and plantarflexor muscles. These impairments may contribute to the high incidence of recurrence of lateral ankle sprain in very active individuals.
authors.affiliation: Department of Rehabilitation, Faculty of Medicine, Laval University, Canada; Centre de santé Valcartier, Valcartier, Canada. Electronic address: marc.perron@fmed.ulaval.ca.
authors.forename: Marc
authors.initials: M
authors.lastname: Perron
authors.affiliation: Department of Rehabilitation, Faculty of Medicine, Laval University, Canada; Centre for Interdisciplinary Research in Rehabilitation and Social Integration, Quebec Rehabilitation Institute, Canada. Electronic address: helene.moffet@fmed.ulaval.ca.
authors.forename: Hélène
authors.initials: H
authors.lastname: Moffet
authors.affiliation: School of Rehabilitation, Faculty of Medicine, University of Montreal, Canada; Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, Canada. Electronic address: sylvie.nadeau@umontreal.ca.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Nadeau
authors.affiliation: Centre for Interdisciplinary Research in Rehabilitation and Social Integration, Quebec Rehabilitation Institute, Canada; Department of Radiology, Faculty of Medicine, Laval University, Canada; National Defense of Canada, CFHS HQ-D Med Pol, Canada. Electronic address: luc.hebert@forces.gc.ca.
authors.forename: Luc J
authors.initials: LJ
authors.lastname: Hébert
authors.affiliation: Centre Hospitalier Universitaire de Québec, Canada. Electronic address: s.belzile@sympatico.ca.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Belzile
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016512:Ankle Injuries / Q000503:physiopathology* / Q000628:therapy; D000843:Ankle Joint / Q000503:physiopathology*; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D026741:Physical Therapy Modalities; D016059:Range of Motion, Articular / Q000502:physiology; D013180:Sprains and Strains / Q000503:physiopathology*; D019415:Torque; D055815:Young Adult
keywords: Ankle injury; Isokinetic testing; Muscle strength