title: Customized noise-stimulation intensity for bipedal stability and unipedal balance deficits associated with functional ankle instability.
abstract: BACKGROUND
  Stochastic resonance stimulation (SRS) administered at an optimal intensity could maximize the effects of treatment on balance.
  
  
  OBJECTIVE
  To determine if a customized optimal SRS intensity is better than a traditional SRS protocol (applying the same percentage sensory threshold intensity for all participants) for improving double- and single-legged balance in participants with or without functional ankle instability (FAI).
  
  
  METHODS
  Case-control study with an embedded crossover design.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  Twelve healthy participants (6 men, 6 women; age = 22 ± 2 years, height = 170 ± 7 cm, mass = 64 ± 10 kg) and 12 participants (6 men, 6 women; age = 23 ± 3 years, height = 174 ± 8 cm, mass = 69 ± 10 kg) with FAI.
  
  
  METHODS
  The SRS optimal intensity level was determined by finding the intensity from 4 experimental intensities at the percentage sensory threshold (25% [SRS₂₅], 50% [SRS₅₀], 75% [SRS₇₅], 90% [SRS₉₀]) that produced the greatest improvement in resultant center-of-pressure velocity (R-COPV) over a control condition (SRS₀) during double-legged balance. We examined double- and single-legged balance tests, comparing optimal SRS (SRS(opt1)) and SRS₀ using a battery of center-of-pressure measures in the frontal and sagittal planes.
  
  
  METHODS
  Anterior-posterior (A-P) and medial-lateral (M-L) center-of-pressure velocity (COPV) and center-of-pressure excursion (COPE), R-COPV, and 95th percentile center-of-pressure area ellipse (COPA-95).
  
  
  RESULTS
  Data were organized into bins that represented optimal (SRS(opt1)), second (SRS(opt2)), third (SRS(opt3)), and fourth (SRS(opt4)) improvement over SRS₀. The SRS(opt1) enhanced R-COPV (P ≤ .05) over SRS₀ and other SRS conditions (SRS₀ = 0.94 ± 0.32 cm/s, SRS(opt1) = 0.80 ± 0.19 cm/s, SRS(opt2) = 0.88 ± 0.24 cm/s, SRS(opt3) = 0.94 ± 0.25 cm/s, SRS(opt4) = 1.00 ± 0.28 cm/s). However, SRS did not improve R-COPV over SRS₀ when data were categorized by sensory threshold. Furthermore, SRS(opt1) improved double-legged balance over SRS₀ from 11% to 25% in all participants for the center-of-pressure frontal- and sagittal-plane assessments (P ≤ .05). The SRS(opt1) also improved single-legged balance over SRS₀ from 10% to 17% in participants with FAI for the center-of-pressure frontal- and sagittal-plane assessments (P ≤ .05). The SRS(opt1) did not improve single-legged balance in participants with stable ankles.
  
  
  CONCLUSIONS
  The SRS(opt1) improved double-legged balance and transfers to enhancing single-legged balance deficits associated with FAI.
authors.affiliation: Department of Kinesiology, University of North Carolina-Greensboro, Greensboro, NC 27412, USA. seross@uncg.edu
authors.forename: Scott E
authors.initials: SE
authors.lastname: Ross
authors.forename: Shelley W
authors.initials: SW
authors.lastname: Linens
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Wright
authors.forename: Brent L
authors.initials: BL
authors.lastname: Arnold
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000843:Ankle Joint / Q000503:physiopathology*; D016022:Case-Control Studies; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000534:rehabilitation*; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D055815:Young Adult