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Title: Effects of vibration intensity, exercise, and motor impairment on leg muscle activity induced by whole-body vibration in people with stroke
Authors: Liao, LR 
Ng, GYF 
Jones, AYM
Chung, RCK 
Pang, MYC 
Issue Date: 1-Dec-2015
Source: Physical therapy, 1 Dec. 2015, v. 95, no. 12, p. 1617-1627
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. Limitations. 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.
Publisher: Oxford University Press
Journal: Physical therapy 
ISSN: 0031-9023
EISSN: 1538-6724
DOI: 10.2522/ptj.20140507
Rights: © 2015 American Physical Therapy Association
This is a pre-copyedited, author-produced version of an article accepted for publication in Physical Therapy following peer review. The version of record Lin-Rong Liao, Gabriel Y.F. Ng, Alice Y.M. Jones, Raymond C.K. Chung, Marco Y.C. Pang, Effects of Vibration Intensity, Exercise, and Motor Impairment on Leg Muscle Activity Induced by Whole-Body Vibration in People With Stroke, Physical Therapy, Volume 95, Issue 12, 1 December 2015, Pages 1617–1627 is available online at:
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