title: Peripheral arterial disease affects the frequency response of ground reaction forces during walking.
abstract: BACKGROUND
  Walking is problematic for patients with peripheral arterial disease. The purpose of this study was to investigate the frequency domain of the ground reaction forces during walking to further elucidate the ambulatory impairment of these patients.
  
  
  METHODS
  Nineteen bilateral peripheral arterial disease patients and nineteen controls were included in this study. Subjects were matched for age and gait speed. Participants walked over a force plate sampling at 600 Hz. PAD patients were tested before (pain-free condition) after the onset of claudication symptoms (pain). We calculated median frequency, frequency bandwidth, and frequency containing 99.5% of the signal for the vertical and anterior-posterior ground reaction forces.
  
  
  RESULTS
  Our results showed reduced median frequency in the vertical and anterior-posterior components of the ground reaction forces between the control group and both peripheral arterial disease conditions. We found reduced frequency bandwidth in the anterior-posterior direction between controls and the peripheral arterial disease pain-free condition. There were no differences in median frequency or bandwidth between peripheral arterial disease pain-free and pain conditions, but an increase in the frequency content for 99.5% of the signal was observed in the pain condition.
  
  
  CONCLUSIONS
  Reduced frequency phenomena during gait in peripheral arterial disease patients compared to velocity-matched controls suggests more sluggish activity within the neuromotor system. Increased frequency phenomena due to pain in these patients suggest a more erratic application of propulsive forces when walking. Frequency domain analysis thus offers new insights into the gait impairments associated with this patient population.
authors.affiliation: Nebraska Biomechanics Core Facility, University of Nebraska at Omaha, Omaha, NE 68182, USA.
authors.forename: Denise
authors.initials: D
authors.lastname: McGrath
authors.forename: Timothy N
authors.initials: TN
authors.lastname: Judkins
authors.forename: Iraklis I
authors.initials: II
authors.lastname: Pipinos
authors.forename: Jason M
authors.initials: JM
authors.lastname: Johanning
authors.forename: Sara A
authors.initials: SA
authors.lastname: Myers
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D005583:Fourier Analysis; D005684:Gait / Q000502:physiology*; D006801:Humans; D007383:Intermittent Claudication / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D058729:Peripheral Arterial Disease / Q000503:physiopathology*; D016138:Walking / Q000502:physiology*