Thesis (M.Sc.) - Cairo University - Faculty of Physical Therapy - Department of Basic Science

Modulation of spinal reflexes is necessary for normal motor performance and locomotor control. It is known that modulation of the H-reflex is altered after neurological injury. Therefore, modulation of the H-reflex by whole body vibration would have clinical implications for use in the rehabilitation setting to improve functional performance. The purpose of this study was to investigate the effect of Whole body vibration on motor neuron excitability in normal subjects. Forty normal male subjects from Zagazig university participated in this study ranging between 18 and 25 years old. They were randomly selected by sealed envelopes and divided into two equal groups (experimental and Control groups),each group contained twenty normal subjects. Experimental group received WBV with a frequency (50-60 Hz) and amplitude (0-10 mm) for 1 minute, 1minute rest period between each vibration set and this was repeated 5 times. Control group stood on WBV device for the same duration while the device was off. H-reflex amplitude, H/M ratio were measured from soleus muscle (posterior tibial nerve) before the study, immediately and 30 minutes after the study in both groups using surface EMG device. There was a significant decrease in H reflex amplitude at 0 min measurement in the study group compared with control group (p=0.002). Also, there was a significant decrease in H reflex amplitude at 30 min measurement in the study group compared with control group (p=0.01). There was a significant decrease in Hmax/Mmax ratio at 0 min in the study group compared with control group (p =0.0001). Also, there was a significant decrease in Hmax/Mmax ratio at 30 min measurement in the study group compared with control group (p=0.03). WBV with a frequency (50-60) Hz and amplitude (0-10 mm) could decrease motor neuron excitability in normal subjects

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