title: Effects of Vibration Intensity, Exercise, and Motor Impairment on Leg Muscle Activity Induced by Whole-Body Vibration in People With Stroke.
abstract: BACKGROUND
  Whole-body vibration (WBV) has increasingly been used as an adjunct treatment in neurological rehabilitation. However, how muscle activation level changes during exposure to different WBV protocols in individuals after stroke remains understudied.
  
  
  OBJECTIVE
  The purpose of this study was to examine the influence of WBV intensity on the magnitude of biceps femoris (BF) and tibialis anterior (TA) muscle activity and its interaction with exercise and with severity of motor impairment and spasticity among individuals with chronic stroke.
  
  
  METHODS
  Each of the 36 individuals with chronic stroke (mean age=57.3 years, SD=10.7) performed 8 different static exercises under 3 WBV conditions: (1) no WBV, (2) low-intensity WBV (frequency=20 Hz, amplitude=0.60 mm, peak acceleration=0.96g), and (3) high-intensity WBV (30 Hz, 0.44 mm, 1.61g). The levels of bilateral TA and BF muscle activity were recorded using surface electromyography (EMG).
  
  
  RESULTS
  The main effect of intensity was significant. Exposure to the low-intensity and high-intensity protocols led to a significantly greater increase in normalized BF and TA muscle electromyographic magnitude in both legs compared with no WBV. The intensity × exercise interaction also was significant, suggesting that the WBV-induced increase in EMG activity was exercise dependent. The EMG responses to WBV were similar between the paretic and nonparetic legs and were not associated with level of lower extremity motor impairment and spasticity.
  
  
  CONCLUSIONS
  Leg muscle activity was measured during static exercises only.
  
  
  CONCLUSIONS
  Adding WBV during exercise significantly increased EMG activity in the TA and BF muscles. The EMG responses to WBV in the paretic and nonparetic legs were similar and were not related to degree of motor impairment and spasticity. The findings are useful for guiding the design of WBV training protocols for people with stroke.
authors.affiliation: L-R. Liao, MPT, Department of Physiotherapy, Guangdong Provincial Work Injury Rehabilitation Hospital, Guangzhou, China, and Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: Lin-Rong
authors.initials: LR
authors.lastname: Liao
authors.affiliation: G.Y.F. Ng, PhD, Department of Rehabilitation Sciences, Hong Kong Polytechnic University.
authors.forename: Gabriel Y F
authors.initials: GY
authors.lastname: Ng
authors.affiliation: A.Y.M. Jones, PhD, School of Allied Health Sciences, Griffith University, Gold Coast, Australia.
authors.forename: Alice Y M
authors.initials: AY
authors.lastname: Jones
authors.affiliation: R.C.K. Chung, PhD, Department of Rehabilitation Sciences, Hong Kong Polytechnic University.
authors.forename: Raymond C K
authors.initials: RC
authors.lastname: Chung
authors.affiliation: M.Y.C. Pang, PhD, Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hong Kong, China. Marco.Pang@polyu.edu.hk.
authors.forename: Marco Y C
authors.initials: MY
authors.lastname: Pang
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D026741:Physical Therapy Modalities; D020521:Stroke / Q000503:physiopathology; D000071939:Stroke Rehabilitation; D016896:Treatment Outcome; D014732:Vibration / Q000627:therapeutic use*