title: Phase dependent modulation of soleus H-reflex in healthy, non-injured individuals while walking with an ankle foot orthosis.
abstract: OBJECTIVE
  To examine the dynamic modulation of the soleus H-reflex while walking with a posterior leaf spring ankle foot orthosis (PAFO).
  
  
  METHODS
  Soleus H-reflexes were evoked on randomly chosen lower limb of fourteen healthy individuals (age range of 22-36 years, 7 women) while walking on a treadmill with and without a PAFO. In order to capture excitability across the duration of the gait cycle, H-reflexes were evoked at heel strike (HS), HS+100ms, HS+200ms, HS+300ms, HS+400ms in the stance phase and at toe-off (TO), TO+100ms, TO+200ms, TO+300ms, TO+400ms in the swing phase respectively.
  
  
  RESULTS
  H-reflex excitability was significantly higher in the form of greater slope of the rise in H-reflex amplitude across the swing phase (p=0.024) and greater mean H-reflex amplitude (p=0.014) in the swing phase of walking with a PAFO. There was no change in the slope (p=0.25) or the mean amplitude of H-reflexes (p=0.22) in the stance phase of walking with a PAFO. Mean background EMG activity between the two walking conditions was not significantly different for both the tibialis anterior (p=0.69) and soleus muscles (p=0.59).
  
  
  CONCLUSIONS
  PAFO increased reflex excitability in the swing phase of walking in healthy individuals. Altered sensory input originating from joint, muscle and cutaneous receptors may be the underlying mechanism for greater reflex excitability. The neurophysiological effect of PAFOs on reflex modulation during walking needs to be tested in persons with neurological injury. The relationship between the sensory input and the reflex output during walking may assist in determining if there exists a neurological disadvantage of using a compensatory device such as a PAFO.
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, FL, USA; Brain Rehabilitation Research Center, Malcolm Randall VA Medical Center, Gainesville, FL, USA; School of Health and Medical Sciences, Seton Hall University, South Orange, NJ, USA. Electronic address: preeti.nair@shu.edu.
authors.forename: Preeti M
authors.initials: PM
authors.lastname: Nair
authors.affiliation: Upper Motorneuron Disorder Spasticity Program, West Park Healthcare Centre, Toronto, ON, Canada; Department of Physical Therapy, University of Toronto, Toronto, ON, Canada.
authors.forename: Chetan P
authors.initials: CP
authors.lastname: Phadke
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, FL, USA; Brain Rehabilitation Research Center, Malcolm Randall VA Medical Center, Gainesville, FL, USA.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Behrman
mesh_terms: D000328:Adult; D004576:Electromyography; D005260:Female; D061826:Foot Orthoses; D005684:Gait / Q000502:physiology; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Ankle foot orthosis; EMG; H-reflex; Walking