title: Strength-Duration Curves of the Common Fibular Nerve Show Hypoexcitability in People With Functional Ankle Instability.
abstract: Some motor impairments, such as decreased reaction of peroneal muscles, altered kinematics, or poor postural control, have been described in people with functional ankle instability. Evidence shows a possible relationship between fibular nerve impairments and functional ankle instability.
  
  
  
  To investigate the electrophysiologic excitability of the common fibular nerve, as measured by strength-duration curves, in subjects with functional ankle instability compared with a control group without ankle impairment.
  
  
  
  A cross-sectional study.
  
  
  
  University Research laboratory.
  
  
  
  Fifty subjects with functional ankle instability (35 men, 15 women; ages 24.36 ± 5.01 years) and 63 uninjured control patients (44 men, 19 women; ages 22.67 ± 4.85 years) were recruited by convenience sampling.
  
  
  
  Not applicable.
  
  
  
  Strength-duration curves of the common fibular nerve were made in all participants. Rheobase, chronaxie, Bawen index, accommodation index, galvano-tetanic threshold, and intensity thresholds for different pulse durations were obtained and compared between the 2 groups.
  
  
  
  Subjects with functional ankle instability show increased values of chronaxie (0.58 ± 0.24 ms versus 0.47 ± 0.16 ms; P = .004), Bawen index (1.53 ± 0.24 versus 1.39 ± 0.21; P = .002), and intensity thresholds for pulse durations ≤2 ms both for rectangular and triangular pulse wave forms. The accommodation index was smaller in subjects with functional ankle instability than controls (3.7 ± 0.72 versus 4.05 ± 0.98; P = .036). The remaining parameters did not show significant differences between groups.
  
  
  
  These findings suggest that subjects with functional ankle instability show a decreased excitability in their common fibular nerve when compared with subjects without ankle injuries.
authors.affiliation: Department of Nursing and Physical Therapy, CEU-San Pablo University, Carretera Boadilla del Monte, Km 5,300, Urbanización Montepríncipe, 28668, Boadilla del Monte, Madrid, Spain(∗). Electronic address: alrodfer@ceu.es.
authors.forename: Ángel L
authors.initials: ÁL
authors.lastname: Rodríguez-Fernández
authors.affiliation: Department of Physical Therapy, University of Sevilla, Sevilla, Spain(†).
authors.forename: Jesús
authors.initials: J
authors.lastname: Rebollo-Roldán
authors.affiliation: Department of Physical Therapy, University of Sevilla, Sevilla, Spain(‡).
authors.forename: José J
authors.initials: JJ
authors.lastname: Jiménez-Rejano
authors.affiliation: Department of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Rey Juan Carlos University, Alcorcón, Madrid, Spain(§).
authors.forename: Javier
authors.initials: J
authors.lastname: Güeita-Rodríguez
mesh_terms: D000328:Adult; D000842:Ankle; D016512:Ankle Injuries; D000843:Ankle Joint; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007593:Joint Instability; D008297:Male; D010543:Peroneal Nerve; D055815:Young Adult