title: Surface electromyography and plantar pressure during walking in young adults with chronic ankle instability.
abstract: OBJECTIVE
  Lateral ankle sprains are common and can manifest into chronic ankle instability (CAI) resulting in altered gait mechanics that may lead to subsequent ankle sprains. Our purpose was to simultaneously analyse muscle activation patterns and plantar pressure distribution during walking in young adults with and without CAI.
  
  
  METHODS
  Seventeen CAI and 17 healthy subjects walked on a treadmill at 4.8 km/h. Plantar pressure measures (pressure-time integral, peak pressure, time to peak pressure, contact area, contact time) of the entire foot and nine specific foot regions and medial-lateral location of centre of pressure (COP) were measured. Surface electromyography (EMG) root mean square (RMS) amplitudes throughout the entire stride cycle and area under RMS curve for 100 ms pre-initial contact (IC) and 200 ms post-IC for anterior tibialis, peroneus longus, medial gastrocnemius, and gluteus medius were collected.
  
  
  RESULTS
  The CAI group demonstrated a more lateral COP throughout the stance phase (P < 0.001 and Cohen's d > 0.9 for all 10 comparisons) and significantly increased peak pressure (P = 0.025) and pressure-time integral (P = 0.049) under the lateral forefoot. The CAI group had lower anterior tibialis RMS areas (P < 0.001) and significantly higher peroneus longus, medial gastrocnemius, and gluteus medius RMS areas during 100 ms pre-IC (P < 0.003). The CAI group had higher gluteus medius sEMG amplitudes during the final 50 % of stance and first 25% of swing (P < 0.05).
  
  
  CONCLUSIONS
  The CAI group had large lateral deviations of their COP location throughout the entire stance phase and increased gluteus medius muscle activation amplitude during late stance through early swing phase.
  
  
  METHODS
  III.
authors: Department of Kinesiology, University of Virginia, 210 Emmet Street South, Charlottesville, VA, 22904-4407, USA. rmk7ye@virginia.edu.|Memorial Gymnasium, POBOX 400407, Charlottesville, VA, USA. rmk7ye@virginia.edu.
authors: Rachel M
authors: RM
authors: Koldenhoven
authors: Department of Kinesiology, University of Virginia, 210 Emmet Street South, Charlottesville, VA, 22904-4407, USA.
authors: Mark A
authors: MA
authors: Feger
authors: Department of Kinesiology, University of Virginia, 210 Emmet Street South, Charlottesville, VA, 22904-4407, USA.|US Navy Medicine Professional Development Center, Bethesda, MD, USA.
authors: John J
authors: JJ
authors: Fraser
authors: Department of Kinesiology, University of Virginia, 210 Emmet Street South, Charlottesville, VA, 22904-4407, USA.
authors: Susan
authors: S
authors: Saliba
authors: Department of Kinesiology, University of Virginia, 210 Emmet Street South, Charlottesville, VA, 22904-4407, USA.
authors: Jay
authors: J
authors: Hertel
mesh_terms: D000328:Adult; D016512:Ankle Injuries / Q000503:physiopathology*; D000843:Ankle Joint / Q000503:physiopathology*; D016022:Case-Control Studies; D002908:Chronic Disease; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D005528:Foot / Q000503:physiopathology*; D005684:Gait / Q000502:physiology; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D017844:Lateral Ligament, Ankle / Q000293:injuries / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D011312:Pressure; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Ankle sprain; Gait; Gluteus medius; Muscle activation; Peroneus longus