The primary purpose of this study is to show whether WBV application has antispastic effect. The secondary aim is to demonstrate whether WBV has neuromodulatory activity on increased stretch reflex and motor neuron activity, which is the basis of the pathophysiology of spasticity.Hypotheses of this study:Whole body vibration in poststroke hemiplegia reduces ankle plantar flexion spasticity.

1. WBV ; reduces plantar flexor spasticity after stroke
2. WBV decreases poststroke spasticity, by decreasing increased stretch reflex and motor neuron activity.

Patients with a stroke of at least 1 month before and with a history of ankle plantar flexion spasticity will be included in the study. Conventional rehabilitation program will be applied to all patients (n=48).The intervention group (n=24) will be applied for 4 weeks, 3days a week, a total of 12 sessions with the WBV powerplate pro5 device. In the WBV group, the frequency and acceleration of vibration will be 30Hz and 18.0m/s2, respectively. The WBV exercise intensity will progressively increase throughout the twelve-session. In the control group, the same procedures will be followed. However, unlike the WBV group, a vibration will be given whose acceleration is attenuated by 99.5%.The surface Electromyography (EMG) and degree of spasticity of soleus muscle will be evaluated at the beginning and end of the all sessions. Soleus H-reflex will be recorded with surface EMG.To obtain the H-reflex response, the posterior tibial nerve in the popliteal region will be stimulated by using a stimulator (FE155 Stimulator HC ADInstrument, Oxford UK) with 1 ms-pulse current. The records will be taken with the Ag / AgCl electrodes (Kendall ®Coviden, self-adhesive electrodes) placed on skin according to the SENIAM protocol. The degree of spasticity will be measured as a soleus muscle tone torque on a fixed angular velocity moving platform.The data will be recorded with the PowerLab data acquisition device

Inclusion Criteria:

1. Ischemic / hemorrhagic poststroke hemiplegia aged 18-90 years,
2. Stroke time ≥1 months,
3. Ankle plantar flexor spasticity MAS ≥1,
4. Brunnstrom stage ≥3 for lower extremity,
5. Patients who were standing for more than five minutes and had a static balance

Exclusion Criteria:

1. Cardiac disorder (rhythm / conduction disorder, cardiac pacemaker, ischemic heart disease)
2. Lower extremity fracture,
3. Findings or suspicion of active deep vein thrombosis,
4. A history of deep vein thrombosis and pulmonary embolism,
5. Orthostatic hypotension
6. Resistant hypertension,
7. Peripheral nerve lesions such as polyneuropathy, radiculopathy
8. Active inflammatory, rheumatologic or infectious disease,
9. Ankle,knee or hip joint contracture,
10. Presence of panic attacks,
11. Patients with dizziness and balance problems,
12. Patients with not intact skin surface to connect electrodes
13. Patients with communication problems: aphasia, major depression
14. Epilepsy
15. Patients who received botulinum A toxin in the last 6 months

Patients will be blind to treatment