title: Localized Ankle Fatigue Development and Fatigue Perception in Adults With or Without Chronic Ankle Instability.
abstract: BACKGROUND
  Fatigue could contribute to ankle-sprain injuries during sport, particularly for individuals with chronic ankle instability (CAI).
  
  
  OBJECTIVE
  To examine whether adults with or without CAI develop fatigue at similar rates when performing ankle exercises at the same relative effort level and whether these groups differ in their subjective perceptions of fatigue.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Biomechanics research laboratory.
  
  
  METHODS
  A total of 11 volunteers with CAI (1 man, 10 women; age = 23.5 ± 3.0 years, height = 168.0 ± 11.2 cm, mass = 64.3 ± 13.5 kg) were recruited for the unstable-ankle group, and 11 volunteers matched for age, height, mass, and sex (1 man, 10 women; age = 24.1 ± 2.1 years, height = 169.5 ± 9.7 cm, mass = 62.3 ± 9.7 kg) were recruited as control participants.
  
  
  METHODS
  Localized muscle fatigue (LMF) was induced in the ankle of the dominant limb using a custom fatigue protocol. Plantar-flexion and dorsiflexion exertions were completed at a rate of 12 cycles per minute at isotonic loads equal to 70% and 30%, respectively, of individual maximal voluntary isometric strength. Intermittent measures of maximal voluntary isometric strength and ratings of perceived exertion (RPEs) were obtained.
  
  
  METHODS
  We compared isometric-strength measures and RPE scores at each observation time (prefatigue and at 4, 8, 12, and 16 minutes into the fatigue protocol) and the group correlations between changes in strength and changes in RPE scores.
  
  
  RESULTS
  Based on ankle-strength measures, the 2 test groups developed LMF at similar rates when exercising at equivalent levels of relative effort. The 2 groups also reported similar levels of discomfort as fatigue progressed.
  
  
  CONCLUSIONS
  The rate of LMF development at the ankle and the associated perception of fatigue did not differ between adults with or without CAI.
authors.affiliation: School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University, Blacksburg.
authors.forename: Courtney A
authors.initials: CA
authors.lastname: Webster
authors.affiliation: School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University, Blacksburg.|Department of Industrial Systems and Engineering, Virginia Polytechnic Institute and State University, Blacksburg.
authors.forename: Maury A
authors.initials: MA
authors.lastname: Nussbaum
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000503:physiopathology*; D002908:Chronic Disease; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000150:complications* / Q000503:physiopathology; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D010465:Perception; D055815:Young Adult
keywords: ankle injuries; ankle torque; joint instability; muscle strength; physical exertion